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The discussion section of a research paper is where the author analyzes and explains the importance of the study's results. It presents the conclusions drawn from the study, compares them to previous research, and addresses any potential limitations or weaknesses. The discussion section should also suggest areas for future research.

Everything is not that complicated if you know where to find the required information. We’ll tell you everything there is to know about writing your discussion. Our easy guide covers all important bits, including research questions and your research results. Do you know how all enumerated events are connected? Well, you will after reading this guide we’ve prepared for you!

What Is in the Discussion Section of a Research Paper

The discussion section of a research paper can be viewed as something similar to the conclusion of your paper. But not literal, of course. It’s an ultimate section where you can talk about the findings of your study. Think about these questions when writing:

Did you answer all of the promised research questions?
Did you mention why your work matters?
What are your findings, and why should anyone even care?
Does your study have a literature review?

So, answer your questions, provide proof, and don’t forget about your promises from the introduction.

How to Write a Discussion Section in 5 Steps

How to write the discussion section of a research paper is something everyone googles eventually. It's just life. But why not make everything easier? In brief, this section we’re talking about must include all following parts:

Answers for research questions
Literature review
Results of the work
Limitations of one’s study
Overall conclusion

Indeed, all those parts may confuse anyone. So by looking at our guide, you'll save yourself some hassle. P.S. All our steps are easy and explained in detail! But if you are looking for the most efficient solution, consider using professional help. Leave your “ write my research paper for me ” order at StudyCrumb and get a customized study tailored to your requirements.

Step 1. Start Strong: Discussion Section of a Research Paper

First and foremost, how to start the discussion section of a research paper? Here’s what you should definitely consider before settling down to start writing:

All essays or papers must begin strong. All readers will not wait for any writer to get to the point. We advise summarizing the paper's main findings.
Moreover, you should relate both discussion and literature review to what you have discovered. Mentioning that would be a plus too.
Make sure that an introduction or start per se is clear and concise. Word count might be needed for school. But any paper should be understandable and not too diluted.

Step 2. Answer the Questions in Your Discussion Section of a Research Paper

Writing the discussion section of a research paper also involves mentioning your questions. Remember that in your introduction, you have promised your readers to answer certain questions. Well, now it’s a perfect time to finally give the awaited answer. You need to explain all possible correlations between your findings, research questions, and literature proposed. You already had hypotheses. So were they correct, or maybe you want to propose certain corrections? Section’s main goal is to avoid open ends. It’s not a story or a fairytale with an intriguing ending. If you have several questions, you must answer them. As simple as that.

Step 3. Relate Your Results in a Discussion Section

Writing a discussion section of a research paper also requires any writer to explain their results. You will undoubtedly include an impactful literature review. However, your readers should not just try and struggle with understanding what are some specific relationships behind previous studies and your results. Your results should sound something like: “This guy in their paper discovered that apples are green. Nevertheless, I have proven via experimentation and research that apples are actually red.” Please, don’t take these results directly. It’s just an initial hypothesis. But what you should definitely remember is any practical implications of your study. Why does it matter and how can anyone use it? That’s the most crucial question.

Step 4. Describe the Limitations in Your Discussion Section

Discussion section of a research paper isn’t limitless. What does that mean? Essentially, it means that you also have to discuss any limitations of your study. Maybe you had some methodological inconsistencies. Possibly, there are no particular theories or not enough information for you to be entirely confident in one’s conclusions. You might say that an available source of literature you have studied does not focus on one’s issue. That’s why one’s main limitation is theoretical. However, keep in mind that your limitations must possess a certain degree of relevancy. You can just say that you haven’t found enough books. Your information must be truthful to research.

Step 5. Conclude Your Discussion Section With Recommendations

Your last step when you write a discussion section in a paper is its conclusion, like in any other academic work. Writer’s conclusion must be as strong as their starting point of the overall work. Check out our brief list of things to know about the conclusion in research paper :

It must present its scientific relevance and importance of your work.
It should include different implications of your research.
It should not, however, discuss anything new or things that you have not mentioned before.
Leave no open questions and carefully complete the work without them.

Discussion Section of a Research Paper Example

All the best example discussion sections of a research paper will be written according to our brief guide. Don’t forget that you need to state your findings and underline the importance of your work. An undoubtedly big part of one’s discussion will definitely be answering and explaining the research questions. In other words, you’ll already have all the knowledge you have so carefully gathered. Our last step for you is to recollect and wrap up your paper. But we’re sure you’ll succeed!

How to Write a Discussion Section: Final Thoughts

Today we have covered how to write a discussion section. That was quite a brief journey, wasn’t it? Just to remind you to focus on these things:

Importance of your study.
Summary of the information you have gathered.
Main findings and conclusions.
Answers to all research questions without an open end.
Correlation between literature review and your results.

But, wait, this guide is not the only thing we can do. Looking for how to write an abstract for a research paper for example? We have such a blog and much more on our platform.

Our academic writing service is just a click away. We are proud to say that our writers are professionals in their fields. Buy a research paper and our experts can provide prompt solutions without compromising the quality.

Discussion Section of a Research Paper: Frequently Asked Questions

1. how long should the discussion section of a research paper be.

Our discussion section of a research paper should not be longer than other sections. So try to keep it short but as informative as possible. It usually contains around 6-7 paragraphs in length. It is enough to briefly summarize all the important data and not to drag it.

2. What's the difference between the discussion and the results?

The difference between discussion and results is very simple and easy to understand. The results only report your main findings. You stated what you have found and how you have done that. In contrast, one’s discussion mentions your findings and explains how they relate to other literature, research questions, and one’s hypothesis. Therefore, it is not only a report but an efficient as well as proper explanation.

3. What's the difference between a discussion and a conclusion?

The difference between discussion and conclusion is also quite easy. Conclusion is a brief summary of all the findings and results. Still, our favorite discussion section interprets and explains your main results. It is an important but more lengthy and wordy part. Besides, it uses extra literature for references.

4. What is the purpose of the discussion section?

The primary purpose of a discussion section is to interpret and describe all your interesting findings. Therefore, you should state what you have learned, whether your hypothesis was correct and how your results can be explained using other sources. If this section is clear to readers, our congratulations as you have succeeded.

Joe Eckel is an expert on Dissertations writing. He makes sure that each student gets precious insights on composing A-grade academic writing.

6 Steps to Write an Excellent Discussion in Your Manuscript

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Table of Contents

The discussion section in scientific manuscripts might be the last few paragraphs, but its role goes far beyond wrapping up. It’s the part of an article where scientists talk about what they found and what it means, where raw data turns into meaningful insights. Therefore, discussion is a vital component of the article.

An excellent discussion is well-organized. We bring to you authors a classic 6-step method for writing discussion sections, with examples to illustrate the functions and specific writing logic of each step. Take a look at how you can impress journal reviewers with a concise and focused discussion section!

Discussion frame structure

Conventionally, a discussion section has three parts: an introductory paragraph, a few intermediate paragraphs, and a conclusion¹. Please follow the steps below:

Steps to Write an Excellent Discussion in Your Manuscript

1.Introduction—mention gaps in previous research¹⁻ ²

Here, you orient the reader to your study. In the first paragraph, it is advisable to mention the research gap your paper addresses.

Example: This study investigated the cognitive effects of a meat-only diet on adults. While earlier studies have explored the impact of a carnivorous diet on physical attributes and agility, they have not explicitly addressed its influence on cognitively intense tasks involving memory and reasoning.

2. Summarizing key findings—let your data speak ¹⁻ ²

After you have laid out the context for your study, recapitulate some of its key findings. Also, highlight key data and evidence supporting these findings.

Example: We found that risk-taking behavior among teenagers correlates with their tendency to invest in cryptocurrencies. Risk takers in this study, as measured by the Cambridge Gambling Task, tended to have an inordinately higher proportion of their savings invested as crypto coins.

3. Interpreting results—compare with other papers¹⁻²

Here, you must analyze and interpret any results concerning the research question or hypothesis. How do the key findings of your study help verify or disprove the hypothesis? What practical relevance does your discovery have?

Example: Our study suggests that higher daily caffeine intake is not associated with poor performance in major sporting events. Athletes may benefit from the cardiovascular benefits of daily caffeine intake without adversely impacting performance.

Remember, unlike the results section, the discussion ideally focuses on locating your findings in the larger body of existing research. Hence, compare your results with those of other peer-reviewed papers.

Example: Although Miller et al. (2020) found evidence of such political bias in a multicultural population, our findings suggest that the bias is weak or virtually non-existent among politically active citizens.

4. Addressing limitations—their potential impact on the results¹⁻²

Discuss the potential impact of limitations on the results. Most studies have limitations, and it is crucial to acknowledge them in the intermediary paragraphs of the discussion section. Limitations may include low sample size, suspected interference or noise in data, low effect size, etc.

Example: This study explored a comprehensive list of adverse effects associated with the novel drug ‘X’. However, long-term studies may be needed to confirm its safety, especially regarding major cardiac events.

5. Implications for future research—how to explore further¹⁻²

Locate areas of your research where more investigation is needed. Concluding paragraphs of the discussion can explain what research will likely confirm your results or identify knowledge gaps your study left unaddressed.

Example: Our study demonstrates that roads paved with the plastic-infused compound ‘Y’ are more resilient than asphalt. Future studies may explore economically feasible ways of producing compound Y in bulk.

6. Conclusion—summarize content¹⁻²

A good way to wind up the discussion section is by revisiting the research question mentioned in your introduction. Sign off by expressing the main findings of your study.

Example: Recent observations suggest that the fish ‘Z’ is moving upriver in many parts of the Amazon basin. Our findings provide conclusive evidence that this phenomenon is associated with rising sea levels and climate change, not due to elevated numbers of invasive predators.

A rigorous and concise discussion section is one of the keys to achieving an excellent paper. It serves as a critical platform for researchers to interpret and connect their findings with the broader scientific context. By detailing the results, carefully comparing them with existing research, and explaining the limitations of this study, you can effectively help reviewers and readers understand the entire research article more comprehensively and deeply¹⁻² , thereby helping your manuscript to be successfully published and gain wider dissemination.

In addition to keeping this writing guide, you can also use Elsevier Language Services to improve the quality of your paper more deeply and comprehensively. We have a professional editing team covering multiple disciplines. With our profound disciplinary background and rich polishing experience, we can significantly optimize all paper modules including the discussion, effectively improve the fluency and rigor of your articles, and make your scientific research results consistent, with its value reflected more clearly. We are always committed to ensuring the quality of papers according to the standards of top journals, improving the publishing efficiency of scientific researchers, and helping you on the road to academic success. Check us out here !

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References:

Masic, I. (2018). How to write an efficient discussion? Medical Archives , 72(3), 306. https://doi.org/10.5455/medarh.2018.72.306-307
Şanlı, Ö., Erdem, S., & Tefik, T. (2014). How to write a discussion section? Urology Research & Practice , 39(1), 20–24. https://doi.org/10.5152/tud.2013.049

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Organizing Your Social Sciences Research Paper

8. The Discussion
Purpose of Guide
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Independent and Dependent Variables
Glossary of Research Terms
Reading Research Effectively
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The purpose of the discussion section is to interpret and describe the significance of your findings in relation to what was already known about the research problem being investigated and to explain any new understanding or insights that emerged as a result of your research. The discussion will always connect to the introduction by way of the research questions or hypotheses you posed and the literature you reviewed, but the discussion does not simply repeat or rearrange the first parts of your paper; the discussion clearly explains how your study advanced the reader's understanding of the research problem from where you left them at the end of your review of prior research.

Annesley, Thomas M. “The Discussion Section: Your Closing Argument.” Clinical Chemistry 56 (November 2010): 1671-1674; Peacock, Matthew. “Communicative Moves in the Discussion Section of Research Articles.” System 30 (December 2002): 479-497.

Importance of a Good Discussion

The discussion section is often considered the most important part of your research paper because it:

Most effectively demonstrates your ability as a researcher to think critically about an issue, to develop creative solutions to problems based upon a logical synthesis of the findings, and to formulate a deeper, more profound understanding of the research problem under investigation;
Presents the underlying meaning of your research, notes possible implications in other areas of study, and explores possible improvements that can be made in order to further develop the concerns of your research;
Highlights the importance of your study and how it can contribute to understanding the research problem within the field of study;
Presents how the findings from your study revealed and helped fill gaps in the literature that had not been previously exposed or adequately described; and,
Engages the reader in thinking critically about issues based on an evidence-based interpretation of findings; it is not governed strictly by objective reporting of information.

Annesley Thomas M. “The Discussion Section: Your Closing Argument.” Clinical Chemistry 56 (November 2010): 1671-1674; Bitchener, John and Helen Basturkmen. “Perceptions of the Difficulties of Postgraduate L2 Thesis Students Writing the Discussion Section.” Journal of English for Academic Purposes 5 (January 2006): 4-18; Kretchmer, Paul. Fourteen Steps to Writing an Effective Discussion Section. San Francisco Edit, 2003-2008.

Structure and Writing Style

I. General Rules

These are the general rules you should adopt when composing your discussion of the results :

Do not be verbose or repetitive; be concise and make your points clearly
Avoid the use of jargon or undefined technical language
Follow a logical stream of thought; in general, interpret and discuss the significance of your findings in the same sequence you described them in your results section [a notable exception is to begin by highlighting an unexpected result or a finding that can grab the reader's attention]
Use the present verb tense, especially for established facts; however, refer to specific works or prior studies in the past tense
If needed, use subheadings to help organize your discussion or to categorize your interpretations into themes

II. The Content

The content of the discussion section of your paper most often includes :

Explanation of results : Comment on whether or not the results were expected for each set of findings; go into greater depth to explain findings that were unexpected or especially profound. If appropriate, note any unusual or unanticipated patterns or trends that emerged from your results and explain their meaning in relation to the research problem.
References to previous research : Either compare your results with the findings from other studies or use the studies to support a claim. This can include re-visiting key sources already cited in your literature review section, or, save them to cite later in the discussion section if they are more important to compare with your results instead of being a part of the general literature review of prior research used to provide context and background information. Note that you can make this decision to highlight specific studies after you have begun writing the discussion section.
Deduction : A claim for how the results can be applied more generally. For example, describing lessons learned, proposing recommendations that can help improve a situation, or highlighting best practices.
Hypothesis : A more general claim or possible conclusion arising from the results [which may be proved or disproved in subsequent research]. This can be framed as new research questions that emerged as a consequence of your analysis.

III. Organization and Structure

Keep the following sequential points in mind as you organize and write the discussion section of your paper:

Think of your discussion as an inverted pyramid. Organize the discussion from the general to the specific, linking your findings to the literature, then to theory, then to practice [if appropriate].
Use the same key terms, narrative style, and verb tense [present] that you used when describing the research problem in your introduction.
Begin by briefly re-stating the research problem you were investigating and answer all of the research questions underpinning the problem that you posed in the introduction.
Describe the patterns, principles, and relationships shown by each major findings and place them in proper perspective. The sequence of this information is important; first state the answer, then the relevant results, then cite the work of others. If appropriate, refer the reader to a figure or table to help enhance the interpretation of the data [either within the text or as an appendix].
Regardless of where it's mentioned, a good discussion section includes analysis of any unexpected findings. This part of the discussion should begin with a description of the unanticipated finding, followed by a brief interpretation as to why you believe it appeared and, if necessary, its possible significance in relation to the overall study. If more than one unexpected finding emerged during the study, describe each of them in the order they appeared as you gathered or analyzed the data. As noted, the exception to discussing findings in the same order you described them in the results section would be to begin by highlighting the implications of a particularly unexpected or significant finding that emerged from the study, followed by a discussion of the remaining findings.
Before concluding the discussion, identify potential limitations and weaknesses if you do not plan to do so in the conclusion of the paper. Comment on their relative importance in relation to your overall interpretation of the results and, if necessary, note how they may affect the validity of your findings. Avoid using an apologetic tone; however, be honest and self-critical [e.g., in retrospect, had you included a particular question in a survey instrument, additional data could have been revealed].
The discussion section should end with a concise summary of the principal implications of the findings regardless of their significance. Give a brief explanation about why you believe the findings and conclusions of your study are important and how they support broader knowledge or understanding of the research problem. This can be followed by any recommendations for further research. However, do not offer recommendations which could have been easily addressed within the study. This would demonstrate to the reader that you have inadequately examined and interpreted the data.

IV. Overall Objectives

The objectives of your discussion section should include the following: I. Reiterate the Research Problem/State the Major Findings

Briefly reiterate the research problem or problems you are investigating and the methods you used to investigate them, then move quickly to describe the major findings of the study. You should write a direct, declarative, and succinct proclamation of the study results, usually in one paragraph.

II. Explain the Meaning of the Findings and Why They are Important

No one has thought as long and hard about your study as you have. Systematically explain the underlying meaning of your findings and state why you believe they are significant. After reading the discussion section, you want the reader to think critically about the results and why they are important. You don’t want to force the reader to go through the paper multiple times to figure out what it all means. If applicable, begin this part of the section by repeating what you consider to be your most significant or unanticipated finding first, then systematically review each finding. Otherwise, follow the general order you reported the findings presented in the results section.

III. Relate the Findings to Similar Studies

No study in the social sciences is so novel or possesses such a restricted focus that it has absolutely no relation to previously published research. The discussion section should relate your results to those found in other studies, particularly if questions raised from prior studies served as the motivation for your research. This is important because comparing and contrasting the findings of other studies helps to support the overall importance of your results and it highlights how and in what ways your study differs from other research about the topic. Note that any significant or unanticipated finding is often because there was no prior research to indicate the finding could occur. If there is prior research to indicate this, you need to explain why it was significant or unanticipated. IV. Consider Alternative Explanations of the Findings

It is important to remember that the purpose of research in the social sciences is to discover and not to prove . When writing the discussion section, you should carefully consider all possible explanations for the study results, rather than just those that fit your hypothesis or prior assumptions and biases. This is especially important when describing the discovery of significant or unanticipated findings.

V. Acknowledge the Study’s Limitations

It is far better for you to identify and acknowledge your study’s limitations than to have them pointed out by your professor! Note any unanswered questions or issues your study could not address and describe the generalizability of your results to other situations. If a limitation is applicable to the method chosen to gather information, then describe in detail the problems you encountered and why. VI. Make Suggestions for Further Research

You may choose to conclude the discussion section by making suggestions for further research [as opposed to offering suggestions in the conclusion of your paper]. Although your study can offer important insights about the research problem, this is where you can address other questions related to the problem that remain unanswered or highlight hidden issues that were revealed as a result of conducting your research. You should frame your suggestions by linking the need for further research to the limitations of your study [e.g., in future studies, the survey instrument should include more questions that ask..."] or linking to critical issues revealed from the data that were not considered initially in your research.

NOTE: Besides the literature review section, the preponderance of references to sources is usually found in the discussion section . A few historical references may be helpful for perspective, but most of the references should be relatively recent and included to aid in the interpretation of your results, to support the significance of a finding, and/or to place a finding within a particular context. If a study that you cited does not support your findings, don't ignore it--clearly explain why your research findings differ from theirs.

V. Problems to Avoid

Do not waste time restating your results . Should you need to remind the reader of a finding to be discussed, use "bridge sentences" that relate the result to the interpretation. An example would be: “In the case of determining available housing to single women with children in rural areas of Texas, the findings suggest that access to good schools is important...," then move on to further explaining this finding and its implications.
As noted, recommendations for further research can be included in either the discussion or conclusion of your paper, but do not repeat your recommendations in the both sections. Think about the overall narrative flow of your paper to determine where best to locate this information. However, if your findings raise a lot of new questions or issues, consider including suggestions for further research in the discussion section.
Do not introduce new results in the discussion section. Be wary of mistaking the reiteration of a specific finding for an interpretation because it may confuse the reader. The description of findings [results section] and the interpretation of their significance [discussion section] should be distinct parts of your paper. If you choose to combine the results section and the discussion section into a single narrative, you must be clear in how you report the information discovered and your own interpretation of each finding. This approach is not recommended if you lack experience writing college-level research papers.
Use of the first person pronoun is generally acceptable. Using first person singular pronouns can help emphasize a point or illustrate a contrasting finding. However, keep in mind that too much use of the first person can actually distract the reader from the main points [i.e., I know you're telling me this--just tell me!].

Analyzing vs. Summarizing. Department of English Writing Guide. George Mason University; Discussion. The Structure, Format, Content, and Style of a Journal-Style Scientific Paper. Department of Biology. Bates College; Hess, Dean R. "How to Write an Effective Discussion." Respiratory Care 49 (October 2004); Kretchmer, Paul. Fourteen Steps to Writing to Writing an Effective Discussion Section. San Francisco Edit, 2003-2008; The Lab Report. University College Writing Centre. University of Toronto; Sauaia, A. et al. "The Anatomy of an Article: The Discussion Section: "How Does the Article I Read Today Change What I Will Recommend to my Patients Tomorrow?” The Journal of Trauma and Acute Care Surgery 74 (June 2013): 1599-1602; Research Limitations & Future Research . Lund Research Ltd., 2012; Summary: Using it Wisely. The Writing Center. University of North Carolina; Schafer, Mickey S. Writing the Discussion. Writing in Psychology course syllabus. University of Florida; Yellin, Linda L. A Sociology Writer's Guide . Boston, MA: Allyn and Bacon, 2009.

Writing Tip

Don’t Over-Interpret the Results!

Interpretation is a subjective exercise. As such, you should always approach the selection and interpretation of your findings introspectively and to think critically about the possibility of judgmental biases unintentionally entering into discussions about the significance of your work. With this in mind, be careful that you do not read more into the findings than can be supported by the evidence you have gathered. Remember that the data are the data: nothing more, nothing less.

MacCoun, Robert J. "Biases in the Interpretation and Use of Research Results." Annual Review of Psychology 49 (February 1998): 259-287; Ward, Paulet al, editors. The Oxford Handbook of Expertise . Oxford, UK: Oxford University Press, 2018.

Another Writing Tip

Don't Write Two Results Sections!

One of the most common mistakes that you can make when discussing the results of your study is to present a superficial interpretation of the findings that more or less re-states the results section of your paper. Obviously, you must refer to your results when discussing them, but focus on the interpretation of those results and their significance in relation to the research problem, not the data itself.

Azar, Beth. "Discussing Your Findings." American Psychological Association gradPSYCH Magazine (January 2006).

Yet Another Writing Tip

Avoid Unwarranted Speculation!

The discussion section should remain focused on the findings of your study. For example, if the purpose of your research was to measure the impact of foreign aid on increasing access to education among disadvantaged children in Bangladesh, it would not be appropriate to speculate about how your findings might apply to populations in other countries without drawing from existing studies to support your claim or if analysis of other countries was not a part of your original research design. If you feel compelled to speculate, do so in the form of describing possible implications or explaining possible impacts. Be certain that you clearly identify your comments as speculation or as a suggestion for where further research is needed. Sometimes your professor will encourage you to expand your discussion of the results in this way, while others don’t care what your opinion is beyond your effort to interpret the data in relation to the research problem.

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How to Write the Discussion Section of a Research Paper

The discussion section of a research paper analyzes and interprets the findings, provides context, compares them with previous studies, identifies limitations, and suggests future research directions.

Updated on September 15, 2023

researchers writing the discussion section of their research paper

Structure your discussion section right, and you’ll be cited more often while doing a greater service to the scientific community. So, what actually goes into the discussion section? And how do you write it?

The discussion section of your research paper is where you let the reader know how your study is positioned in the literature, what to take away from your paper, and how your work helps them. It can also include your conclusions and suggestions for future studies.

First, we’ll define all the parts of your discussion paper, and then look into how to write a strong, effective discussion section for your paper or manuscript.

Discussion section: what is it, what it does

The discussion section comes later in your paper, following the introduction, methods, and results. The discussion sets up your study’s conclusions. Its main goals are to present, interpret, and provide a context for your results.

What is it?

The discussion section provides an analysis and interpretation of the findings, compares them with previous studies, identifies limitations, and suggests future directions for research.

This section combines information from the preceding parts of your paper into a coherent story. By this point, the reader already knows why you did your study (introduction), how you did it (methods), and what happened (results). In the discussion, you’ll help the reader connect the ideas from these sections.

Why is it necessary?

The discussion provides context and interpretations for the results. It also answers the questions posed in the introduction. While the results section describes your findings, the discussion explains what they say. This is also where you can describe the impact or implications of your research.

Adds context for your results

Most research studies aim to answer a question, replicate a finding, or address limitations in the literature. These goals are first described in the introduction. However, in the discussion section, the author can refer back to them to explain how the study's objective was achieved.

Shows what your results actually mean and real-world implications

The discussion can also describe the effect of your findings on research or practice. How are your results significant for readers, other researchers, or policymakers?

What to include in your discussion (in the correct order)

A complete and effective discussion section should at least touch on the points described below.

Summary of key findings

The discussion should begin with a brief factual summary of the results. Concisely overview the main results you obtained.

Begin with key findings with supporting evidence

Your results section described a list of findings, but what message do they send when you look at them all together?

Your findings were detailed in the results section, so there’s no need to repeat them here, but do provide at least a few highlights. This will help refresh the reader’s memory and help them focus on the big picture.

Read the first paragraph of the discussion section in this article (PDF) for an example of how to start this part of your paper. Notice how the authors break down their results and follow each description sentence with an explanation of why each finding is relevant.

State clearly and concisely

Following a clear and direct writing style is especially important in the discussion section. After all, this is where you will make some of the most impactful points in your paper. While the results section often contains technical vocabulary, such as statistical terms, the discussion section lets you describe your findings more clearly.

Interpretation of results

Once you’ve given your reader an overview of your results, you need to interpret those results. In other words, what do your results mean? Discuss the findings’ implications and significance in relation to your research question or hypothesis.

Analyze and interpret your findings

Look into your findings and explore what’s behind them or what may have caused them. If your introduction cited theories or studies that could explain your findings, use these sources as a basis to discuss your results.

For example, look at the second paragraph in the discussion section of this article on waggling honey bees. Here, the authors explore their results based on information from the literature.

Unexpected or contradictory results

Sometimes, your findings are not what you expect. Here’s where you describe this and try to find a reason for it. Could it be because of the method you used? Does it have something to do with the variables analyzed? Comparing your methods with those of other similar studies can help with this task.

Context and comparison with previous work

Refer to related studies to place your research in a larger context and the literature. Compare and contrast your findings with existing literature, highlighting similarities, differences, and/or contradictions.

How your work compares or contrasts with previous work

Studies with similar findings to yours can be cited to show the strength of your findings. Information from these studies can also be used to help explain your results. Differences between your findings and others in the literature can also be discussed here.

How to divide this section into subsections

If you have more than one objective in your study or many key findings, you can dedicate a separate section to each of these. Here’s an example of this approach. You can see that the discussion section is divided into topics and even has a separate heading for each of them.

Limitations

Many journals require you to include the limitations of your study in the discussion. Even if they don’t, there are good reasons to mention these in your paper.

Why limitations don’t have a negative connotation

A study’s limitations are points to be improved upon in future research. While some of these may be flaws in your method, many may be due to factors you couldn’t predict.

Examples include time constraints or small sample sizes. Pointing this out will help future researchers avoid or address these issues. This part of the discussion can also include any attempts you have made to reduce the impact of these limitations, as in this study .

How limitations add to a researcher's credibility

Pointing out the limitations of your study demonstrates transparency. It also shows that you know your methods well and can conduct a critical assessment of them.

Implications and significance

The final paragraph of the discussion section should contain the take-home messages for your study. It can also cite the “strong points” of your study, to contrast with the limitations section.

Restate your hypothesis

Remind the reader what your hypothesis was before you conducted the study.

How was it proven or disproven?

Identify your main findings and describe how they relate to your hypothesis.

How your results contribute to the literature

Were you able to answer your research question? Or address a gap in the literature?

Future implications of your research

Describe the impact that your results may have on the topic of study. Your results may show, for instance, that there are still limitations in the literature for future studies to address. There may be a need for studies that extend your findings in a specific way. You also may need additional research to corroborate your findings.

Sample discussion section

This fictitious example covers all the aspects discussed above. Your actual discussion section will probably be much longer, but you can read this to get an idea of everything your discussion should cover.

Our results showed that the presence of cats in a household is associated with higher levels of perceived happiness by its human occupants. These findings support our hypothesis and demonstrate the association between pet ownership and well-being.

The present findings align with those of Bao and Schreer (2016) and Hardie et al. (2023), who observed greater life satisfaction in pet owners relative to non-owners. Although the present study did not directly evaluate life satisfaction, this factor may explain the association between happiness and cat ownership observed in our sample.

Our findings must be interpreted in light of some limitations, such as the focus on cat ownership only rather than pets as a whole. This may limit the generalizability of our results.

Nevertheless, this study had several strengths. These include its strict exclusion criteria and use of a standardized assessment instrument to investigate the relationships between pets and owners. These attributes bolster the accuracy of our results and reduce the influence of confounding factors, increasing the strength of our conclusions. Future studies may examine the factors that mediate the association between pet ownership and happiness to better comprehend this phenomenon.

This brief discussion begins with a quick summary of the results and hypothesis. The next paragraph cites previous research and compares its findings to those of this study. Information from previous studies is also used to help interpret the findings. After discussing the results of the study, some limitations are pointed out. The paper also explains why these limitations may influence the interpretation of results. Then, final conclusions are drawn based on the study, and directions for future research are suggested.

How to make your discussion flow naturally

If you find writing in scientific English challenging, the discussion and conclusions are often the hardest parts of the paper to write. That’s because you’re not just listing up studies, methods, and outcomes. You’re actually expressing your thoughts and interpretations in words.

How formal should it be?
What words should you use, or not use?
How do you meet strict word limits, or make it longer and more informative?

Always give it your best, but sometimes a helping hand can, well, help. Getting a professional edit can help clarify your work’s importance while improving the English used to explain it. When readers know the value of your work, they’ll cite it. We’ll assign your study to an expert editor knowledgeable in your area of research. Their work will clarify your discussion, helping it to tell your story. Find out more about AJE Editing.

Adam Goulston, PsyD, MS, MBA, MISD, ELS

Science Marketing Consultant

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Ensure your structure and ideas are consistent and clearly communicated

Pair your Premium Editing with our add-on service Presubmission Review for an overall assessment of your manuscript.

How to Start a Discussion Section in Research? [with Examples]

The examples below are from 72,017 full-text PubMed research papers that I analyzed in order to explore common ways to start writing the Discussion section.

Research papers included in this analysis were selected at random from those uploaded to PubMed Central between the years 2016 and 2021. Note that I used the BioC API to download the data (see the References section below).

Examples of how to start writing the Discussion section

In the Discussion section, you should explain the meaning of your results, their importance, and implications. [for more information, see: How to Write & Publish a Research Paper: Step-by-Step Guide ]

The Discussion section can:

1. Start by restating the study objective

“ The purpose of this study was to investigate the relationship between muscle synergies and motion primitives of the upper limb motions.” Taken from the Discussion section of this article on PubMed

“ The main objective of this study was to identify trajectories of autonomy.” Taken from the Discussion section of this article on PubMed

“ In the present study, we investigated the whole brain regional homogeneity in patients with melancholic MDD and non-melancholic MDD at rest . “ Taken from the Discussion section of this article on PubMed

2. Start by mentioning the main finding

“ We found that autocracy and democracy have acted as peaks in an evolutionary landscape of possible modes of institutional arrangements.” Taken from the Discussion section of this article on PubMed

“ In this study, we demonstrated that the neural mechanisms of rhythmic movements and skilled movements are similar.” Taken from the Discussion section of this article on PubMed

“ The results of this study show that older adults are a diverse group concerning their activities on the Internet.” Taken from the Discussion section of this article on PubMed

3. Start by pointing out the strength of the study

“ To our knowledge, this investigation is by far the largest epidemiological study employing real-time PCR to study periodontal pathogens in subgingival plaque.” Taken from the Discussion section of this article on PubMed

“ This is the first human subject research using the endoscopic hemoglobin oxygen saturation imaging technology for patients with aero-digestive tract cancers or adenomas.” Taken from the Discussion section of this article on PubMed

“ In this work, we introduced a new real-time flow imaging method and systematically demonstrated its effectiveness with both flow phantom experiments and in vivo experiments.” Taken from the Discussion section of this article on PubMed

Most used words at the start of the Discussion

Here are the top 10 phrases used to start a discussion section in our dataset:

Rank	Phrase	Percent of occurrences
1	“In this study,…”	4.48%
2	“In the present study,…”	1.66%
3	“To our knowledge,…”	0.73%
4	“To the best of our knowledge,…”	0.51%
5	“In the current study,…”	0.38%
6	“The aim of this study was…”	0.38%
7	“This is the first study to…”	0.28%
8	“The purpose of this study was to…”	0.22%
9	“The results of the present study…”	0.14%
10	“The aim of the present study was…”	0.11%

Comeau DC, Wei CH, Islamaj Doğan R, and Lu Z. PMC text mining subset in BioC: about 3 million full text articles and growing, Bioinformatics , btz070, 2019.

Discussion Section Examples and Writing Tips

In this blog, we look at how to write the discussion section of a research paper. We will go through plenty of discussion examples and understand how to construct a great discussion section for your research paper.

1. What is the purpose of the discussion section?

The discussion section is one of the most important sections of your research paper. This is where you interpret your results, highlight your contributions, and explain the value of your work to your readers. This is one of the challenging parts to write because the author must clearly explain the significance of their results and tie everything back to the research questions.

2. How should I structure my discussion section?

Generally, the discussion section of a research paper typically contains the following parts.

Research summary It is a good idea to start this section with an overall summary of your work and highlight the main findings of your research.

Interpretation of findings You must interpret your findings clearly to your readers one by one.

Comparison with literature You must talk about how your results fit into existing research in the literature.

Implications of your work You should talk about the implications and possible benefits of your research.

Limitations You should talk about the possible limitations and shortcomings of your research

Future work And finally, you can talk about the possible future directions of your work.

3. Discussion Examples

Let’s look at some examples of the discussion section. We will be looking at discussion examples from different fields and of different formats. We have split this section into multiple components so that it is easy for you to digest and understand.

3.1. An example of research summary in discussion

It is a good idea to start your discussion section with the summary of your work. The best way to do this will be to restate your research question, and then reminding your readers about your methods, and finally providing an overall summary of your results.

Our aims were to compare the effectiveness and user-friendliness of different storm detection software for storm tracking. On the basis of these aims, we ran multiple experiments with the same conditions using different storm detection software. Our results showed that in both speed and accuracy of data, ‘software A’ performed better than ‘software B’. _ Aims summary _ Methodology summary _ Results summary

This discussion example is from an engineering research paper. The authors are restating their aims first, which is to compare different types of storm-tracking software. Then, they are providing a brief summary of the methods. Here, they are testing different storm-tracking software under different conditions to see which performs the best. Then, they are finally providing their main finding which is that they found ‘software A’ better than ‘software B’. This is a very good example of how to start the discussion section by presenting a summary of your work.

3.2. An example of result interpretation in discussion

The next step is to interpret your results. You have to explain your results clearly to your readers. Here is a discussion example that shows how to interpret your results.

The results of this study indicate significant differences between classical music and pop music in terms of their effects on memory recall and cognition. This implies that as the complexity of the music increases, so does its ability to facilitate cognitive processing. This finding aligns with the well-known “Mozart effect,” which suggests that listening to classical music can enhance cognitive function. _ Result _ Interpretation _ Additional evidence

The authors are saying that their results show that there is a significant difference between pop music and classical music in terms of memory recall and cognition. Now they are providing their interpretation of the findings. They think it is because there is a link between the complexity of music and cognitive processing. They are also making a reference to a well-known theory called the ‘Mozart effect’ to back up their findings. It is a nicely written passage and the author’s interpretation sounds very convincing and credible.

3.3. An example of literature comparison in discussion

The next step is to compare your results to the literature. You have to explain clearly how your findings compare with similar findings made by other researchers. Here is a discussion example where authors are providing details of papers in the literature that both support and oppose their findings.

Our analysis predicts that climate change will have a significant impact on wheat yield. This finding undermines one of the central pieces of evidence in some previous simulation studies [1-3] that suggest a negative effect of climate change on wheat yield, but the result is entirely consistent with the predictions of other research [4-5] that suggests the overall change in climate could result in increases in wheat yield. _ Result _ Comparison with literature

The authors are saying that their results show that climate change will have a significant effect on wheat production. Then, they are saying that there are some papers in the literature that are in agreement with their findings. However, there are also many papers in the literature that disagree with their findings. This is very important. Your discussion should be two-sided, not one-sided. You should not ignore the literature that doesn’t corroborate your findings.

3.4. An example of research implications in discussion

The next step is to explain to your readers how your findings will benefit society and the research community. You have to clearly explain the value of your work to your readers. Here is a discussion example where authors explain the implications of their research.

The results contribute insights with regard to the management of wildfire events using artificial intelligence. One could easily argue that the obvious practical implication of this study is that it proposes utilizing cloud-based machine vision to detect wildfires in real-time, even before the first responders receive emergency calls. _ Your finding _ Implications of your finding

In this paper, the authors are saying that their findings indicate that Artificial intelligence can be used to effectively manage wildfire events. Then, they are talking about the practical implications of their study. They are saying that their work has proven that machine learning can be used to detect wildfires in real-time. This is a great practical application and can save thousands of lives. As you can see, after reading this passage, you can immediately understand the value and significance of the work.

3.5. An example of limitations in discussion

It is very important that you discuss the limitations of your study. Limitations are flaws and shortcomings of your study. You have to tell your readers how your limitations might influence the outcomes and conclusions of your research. Most studies will have some form of limitation. So be honest and don’t hide your limitations. In reality, your readers and reviewers will be impressed with your paper if you are upfront about your limitations.

Study design and small sample size are important limitations. This could have led to an overestimation of the effect. Future research should reconfirm these findings by conducting larger-scale studies. _ Limitation _ How it might affect the results? _ How to fix the limitation?

Here is a discussion example where the author talks about study limitations. The authors are saying that the main limitations of the study are the small sample size and weak study design. Then they explain how this might have affected their results. They are saying that it is possible that they are overestimating the actual effect they are measuring. Then finally they are telling the readers that more studies with larger sample sizes should be conducted to reconfirm the findings.

As you can see, the authors are clearly explaining three things here:

3.6. An example of future work in discussion

It is important to remember not to end your paper with limitations. Finish your paper on a positive note by telling your readers about the benefits of your research and possible future directions. Here is a discussion example where the author talks about future work.

Our study highlights useful insights about the potential of biomass as a renewable energy source. Future research can extend this research in several ways, including research on how to tackle challenges that hinder the sustainability of renewable energy sources towards climate change mitigation, such as market failures, lack of information and access to raw materials. _ Benefits of your work _ Future work

The authors are starting the final paragraph of the discussion section by highlighting the benefit of their work which is the use of biomass as a renewable source of energy. Then they talk about future research. They are saying that future research can focus on how to improve the sustainability of biomass production. This is a very good example of how to finish the discussion section of your paper on a positive note.

4. Frequently Asked Questions

Sometimes you will have negative or unexpected results in your paper. You have to talk about it in your discussion section. A lot of students find it difficult to write this part. The best way to handle this situation is not to look at results as either positive or negative. A result is a result, and you will always have something important and interesting to say about your findings. Just spend some time investigating what might have caused this result and tell your readers about it.

You must talk about the limitations of your work in the discussion section of the paper. One of the important qualities that the scientific community expects from a researcher is honesty and admitting when they have made a mistake. The important trick you have to learn while presenting your limitations is to present them in a constructive way rather than being too negative about them. You must try to use positive language even when you are talking about major limitations of your work.

If you have something exciting to say about your results or found something new that nobody else has found before, then, don’t be modest and use flat language when presenting this in the discussion. Use words like ‘break through’, ‘indisputable evidence’, ‘exciting proposition’ to increase the impact of your findings.

Important thing to remember is not to overstate your findings. If you found something really interesting but are not 100% sure, you must not mislead your readers. The best way to do this will be to use words like ‘it appears’ and ‘it seems’. This will tell the readers that there is a slight possibility that you might be wrong.

Figures and Tables in Research Papers – Tips and Examples

In this blog, we will look at best practices for presenting tables and figures in your research paper.

Critical Literature Review : How to Critique a Research Article?

In this blog, we will look at how to use constructive language when critiquing other’s work in your research paper.

Introduction Paragraph Examples and Writing Tips

In this blog, we will go through a few introduction paragraph examples and understand how to construct a great introduction paragraph for your research paper.

Materials and Methods Examples and Writing Tips

In this blog, we will go through many materials and methods examples and understand how to write a clear and concise method section for your research paper.

3 Costly Mistakes to Avoid in the Research Introduction

In this blog, we will discuss three common mistakes that beginner writers make while writing the research paper introduction.

Technical Terms, Notations, and Scientific Jargon in Research Papers

In this blog, we will teach you how to use specialized terminology in your research papers with some practical examples.

How to Write a Discussion Section for a Research Paper

We’ve talked about several useful writing tips that authors should consider while drafting or editing their research papers. In particular, we’ve focused on figures and legends , as well as the Introduction , Methods , and Results . Now that we’ve addressed the more technical portions of your journal manuscript, let’s turn to the analytical segments of your research article. In this article, we’ll provide tips on how to write a strong Discussion section that best portrays the significance of your research contributions.

What is the Discussion section of a research paper?

In a nutshell, your Discussion fulfills the promise you made to readers in your Introduction . At the beginning of your paper, you tell us why we should care about your research. You then guide us through a series of intricate images and graphs that capture all the relevant data you collected during your research. We may be dazzled and impressed at first, but none of that matters if you deliver an anti-climactic conclusion in the Discussion section!

Are you feeling pressured? Don’t worry. To be honest, you will edit the Discussion section of your manuscript numerous times. After all, in as little as one to two paragraphs ( Nature ‘s suggestion based on their 3,000-word main body text limit), you have to explain how your research moves us from point A (issues you raise in the Introduction) to point B (our new understanding of these matters). You must also recommend how we might get to point C (i.e., identify what you think is the next direction for research in this field). That’s a lot to say in two paragraphs!

So, how do you do that? Let’s take a closer look.

What should I include in the Discussion section?

As we stated above, the goal of your Discussion section is to answer the questions you raise in your Introduction by using the results you collected during your research . The content you include in the Discussions segment should include the following information:

Remind us why we should be interested in this research project.
Describe the nature of the knowledge gap you were trying to fill using the results of your study.
Don’t repeat your Introduction. Instead, focus on why this particular study was needed to fill the gap you noticed and why that gap needed filling in the first place.
Mainly, you want to remind us of how your research will increase our knowledge base and inspire others to conduct further research.
Clearly tell us what that piece of missing knowledge was.
Answer each of the questions you asked in your Introduction and explain how your results support those conclusions.
Make sure to factor in all results relevant to the questions (even if those results were not statistically significant).
Focus on the significance of the most noteworthy results.
If conflicting inferences can be drawn from your results, evaluate the merits of all of them.
Don’t rehash what you said earlier in the Results section. Rather, discuss your findings in the context of answering your hypothesis. Instead of making statements like “[The first result] was this…,” say, “[The first result] suggests [conclusion].”
Do your conclusions line up with existing literature?
Discuss whether your findings agree with current knowledge and expectations.
Keep in mind good persuasive argument skills, such as explaining the strengths of your arguments and highlighting the weaknesses of contrary opinions.
If you discovered something unexpected, offer reasons. If your conclusions aren’t aligned with current literature, explain.
Address any limitations of your study and how relevant they are to interpreting your results and validating your findings.
Make sure to acknowledge any weaknesses in your conclusions and suggest room for further research concerning that aspect of your analysis.
Make sure your suggestions aren’t ones that should have been conducted during your research! Doing so might raise questions about your initial research design and protocols.
Similarly, maintain a critical but unapologetic tone. You want to instill confidence in your readers that you have thoroughly examined your results and have objectively assessed them in a way that would benefit the scientific community’s desire to expand our knowledge base.
Recommend next steps.
Your suggestions should inspire other researchers to conduct follow-up studies to build upon the knowledge you have shared with them.
Keep the list short (no more than two).

How to Write the Discussion Section

The above list of what to include in the Discussion section gives an overall idea of what you need to focus on throughout the section. Below are some tips and general suggestions about the technical aspects of writing and organization that you might find useful as you draft or revise the contents we’ve outlined above.

Technical writing elements

Embrace active voice because it eliminates the awkward phrasing and wordiness that accompanies passive voice.
Use the present tense, which should also be employed in the Introduction.
Sprinkle with first person pronouns if needed, but generally, avoid it. We want to focus on your findings.
Maintain an objective and analytical tone.

Discussion section organization

Keep the same flow across the Results, Methods, and Discussion sections.
We develop a rhythm as we read and parallel structures facilitate our comprehension. When you organize information the same way in each of these related parts of your journal manuscript, we can quickly see how a certain result was interpreted and quickly verify the particular methods used to produce that result.
Notice how using parallel structure will eliminate extra narration in the Discussion part since we can anticipate the flow of your ideas based on what we read in the Results segment. Reducing wordiness is important when you only have a few paragraphs to devote to the Discussion section!
Within each subpart of a Discussion, the information should flow as follows: (A) conclusion first, (B) relevant results and how they relate to that conclusion and (C) relevant literature.
End with a concise summary explaining the big-picture impact of your study on our understanding of the subject matter. At the beginning of your Discussion section, you stated why this particular study was needed to fill the gap you noticed and why that gap needed filling in the first place. Now, it is time to end with “how your research filled that gap.”

Discussion Part 1: Summarizing Key Findings

Begin the Discussion section by restating your statement of the problem and briefly summarizing the major results. Do not simply repeat your findings. Rather, try to create a concise statement of the main results that directly answer the central research question that you stated in the Introduction section . This content should not be longer than one paragraph in length.

Many researchers struggle with understanding the precise differences between a Discussion section and a Results section . The most important thing to remember here is that your Discussion section should subjectively evaluate the findings presented in the Results section, and in relatively the same order. Keep these sections distinct by making sure that you do not repeat the findings without providing an interpretation.

Phrase examples: Summarizing the results

The findings indicate that …
These results suggest a correlation between A and B …
The data present here suggest that …
An interpretation of the findings reveals a connection between…

Discussion Part 2: Interpreting the Findings

What do the results mean? It may seem obvious to you, but simply looking at the figures in the Results section will not necessarily convey to readers the importance of the findings in answering your research questions.

The exact structure of interpretations depends on the type of research being conducted. Here are some common approaches to interpreting data:

Identifying correlations and relationships in the findings
Explaining whether the results confirm or undermine your research hypothesis
Giving the findings context within the history of similar research studies
Discussing unexpected results and analyzing their significance to your study or general research
Offering alternative explanations and arguing for your position

Organize the Discussion section around key arguments, themes, hypotheses, or research questions or problems. Again, make sure to follow the same order as you did in the Results section.

Discussion Part 3: Discussing the Implications

In addition to providing your own interpretations, show how your results fit into the wider scholarly literature you surveyed in the literature review section. This section is called the implications of the study . Show where and how these results fit into existing knowledge, what additional insights they contribute, and any possible consequences that might arise from this knowledge, both in the specific research topic and in the wider scientific domain.

Questions to ask yourself when dealing with potential implications:

Do your findings fall in line with existing theories, or do they challenge these theories or findings? What new information do they contribute to the literature, if any? How exactly do these findings impact or conflict with existing theories or models?
What are the practical implications on actual subjects or demographics?
What are the methodological implications for similar studies conducted either in the past or future?

Your purpose in giving the implications is to spell out exactly what your study has contributed and why researchers and other readers should be interested.

Phrase examples: Discussing the implications of the research

These results confirm the existing evidence in X studies…
The results are not in line with the foregoing theory that…
This experiment provides new insights into the connection between…
These findings present a more nuanced understanding of…
While previous studies have focused on X, these results demonstrate that Y.

Step 4: Acknowledging the limitations

All research has study limitations of one sort or another. Acknowledging limitations in methodology or approach helps strengthen your credibility as a researcher. Study limitations are not simply a list of mistakes made in the study. Rather, limitations help provide a more detailed picture of what can or cannot be concluded from your findings. In essence, they help temper and qualify the study implications you listed previously.

Study limitations can relate to research design, specific methodological or material choices, or unexpected issues that emerged while you conducted the research. Mention only those limitations directly relate to your research questions, and explain what impact these limitations had on how your study was conducted and the validity of any interpretations.

Possible types of study limitations:

Insufficient sample size for statistical measurements
Lack of previous research studies on the topic
Methods/instruments/techniques used to collect the data
Limited access to data
Time constraints in properly preparing and executing the study

After discussing the study limitations, you can also stress that your results are still valid. Give some specific reasons why the limitations do not necessarily handicap your study or narrow its scope.

Phrase examples: Limitations sentence beginners

“There may be some possible limitations in this study.”
“The findings of this study have to be seen in light of some limitations.”
“The first limitation is the…The second limitation concerns the…”
“The empirical results reported herein should be considered in the light of some limitations.”
“This research, however, is subject to several limitations.”
“The primary limitation to the generalization of these results is…”
“Nonetheless, these results must be interpreted with caution and a number of limitations should be borne in mind.”

Discussion Part 5: Giving Recommendations for Further Research

Based on your interpretation and discussion of the findings, your recommendations can include practical changes to the study or specific further research to be conducted to clarify the research questions. Recommendations are often listed in a separate Conclusion section , but often this is just the final paragraph of the Discussion section.

Suggestions for further research often stem directly from the limitations outlined. Rather than simply stating that “further research should be conducted,” provide concrete specifics for how future can help answer questions that your research could not.

Phrase examples: Recommendation sentence beginners

Further research is needed to establish …
There is abundant space for further progress in analyzing…
A further study with more focus on X should be done to investigate…
Further studies of X that account for these variables must be undertaken.

Consider Receiving Professional Language Editing

As you edit or draft your research manuscript, we hope that you implement these guidelines to produce a more effective Discussion section. And after completing your draft, don’t forget to submit your work to a professional proofreading and English editing service like Wordvice, including our manuscript editing service for paper editing , cover letter editing , SOP editing , and personal statement proofreading services. Language editors not only proofread and correct errors in grammar, punctuation, mechanics, and formatting but also improve terms and revise phrases so they read more naturally. Wordvice is an industry leader in providing high-quality revision for all types of academic documents.

For additional information about how to write a strong research paper, make sure to check out our full research writing series !

Wordvice Writing Resources

How to Write a Research Paper Introduction
Which Verb Tenses to Use in a Research Paper
How to Write an Abstract for a Research Paper
How to Write a Research Paper Title
Useful Phrases for Academic Writing
Common Transition Terms in Academic Papers
Active and Passive Voice in Research Papers
100+ Verbs That Will Make Your Research Writing Amazing
Tips for Paraphrasing in Research Papers

Additional Academic Resources

Guide for Authors. (Elsevier)
How to Write the Results Section of a Research Paper. (Bates College)
Structure of a Research Paper. (University of Minnesota Biomedical Library)
How to Choose a Target Journal (Springer)
How to Write Figures and Tables (UNC Writing Center)

How To Write The Discussion Chapter

A Simple Explainer With Examples + Free Template

By: Jenna Crossley (PhD) | Reviewed By: Dr. Eunice Rautenbach | August 2021

If you’re reading this, chances are you’ve reached the discussion chapter of your thesis or dissertation and are looking for a bit of guidance. Well, you’ve come to the right place ! In this post, we’ll unpack and demystify the typical discussion chapter in straightforward, easy to understand language, with loads of examples .

Overview: The Discussion Chapter

What the discussion chapter is
What to include in your discussion
How to write up your discussion
A few tips and tricks to help you along the way
Free discussion template

What (exactly) is the discussion chapter?

The discussion chapter is where you interpret and explain your results within your thesis or dissertation. This contrasts with the results chapter, where you merely present and describe the analysis findings (whether qualitative or quantitative ). In the discussion chapter, you elaborate on and evaluate your research findings, and discuss the significance and implications of your results .

In this chapter, you’ll situate your research findings in terms of your research questions or hypotheses and tie them back to previous studies and literature (which you would have covered in your literature review chapter). You’ll also have a look at how relevant and/or significant your findings are to your field of research, and you’ll argue for the conclusions that you draw from your analysis. Simply put, the discussion chapter is there for you to interact with and explain your research findings in a thorough and coherent manner.

Free template for discussion or thesis discussion section

What should I include in the discussion chapter?

First things first: in some studies, the results and discussion chapter are combined into one chapter . This depends on the type of study you conducted (i.e., the nature of the study and methodology adopted), as well as the standards set by the university. So, check in with your university regarding their norms and expectations before getting started. In this post, we’ll treat the two chapters as separate, as this is most common.

Basically, your discussion chapter should analyse , explore the meaning and identify the importance of the data you presented in your results chapter. In the discussion chapter, you’ll give your results some form of meaning by evaluating and interpreting them. This will help answer your research questions, achieve your research aims and support your overall conclusion (s). Therefore, you discussion chapter should focus on findings that are directly connected to your research aims and questions. Don’t waste precious time and word count on findings that are not central to the purpose of your research project.

As this chapter is a reflection of your results chapter, it’s vital that you don’t report any new findings . In other words, you can’t present claims here if you didn’t present the relevant data in the results chapter first. So, make sure that for every discussion point you raise in this chapter, you’ve covered the respective data analysis in the results chapter. If you haven’t, you’ll need to go back and adjust your results chapter accordingly.

If you’re struggling to get started, try writing down a bullet point list everything you found in your results chapter. From this, you can make a list of everything you need to cover in your discussion chapter. Also, make sure you revisit your research questions or hypotheses and incorporate the relevant discussion to address these. This will also help you to see how you can structure your chapter logically.

Need a helping hand?

How to write the discussion chapter

Now that you’ve got a clear idea of what the discussion chapter is and what it needs to include, let’s look at how you can go about structuring this critically important chapter. Broadly speaking, there are six core components that need to be included, and these can be treated as steps in the chapter writing process.

Step 1: Restate your research problem and research questions

The first step in writing up your discussion chapter is to remind your reader of your research problem , as well as your research aim(s) and research questions . If you have hypotheses, you can also briefly mention these. This “reminder” is very important because, after reading dozens of pages, the reader may have forgotten the original point of your research or been swayed in another direction. It’s also likely that some readers skip straight to your discussion chapter from the introduction chapter , so make sure that your research aims and research questions are clear.

Step 2: Summarise your key findings

Next, you’ll want to summarise your key findings from your results chapter. This may look different for qualitative and quantitative research , where qualitative research may report on themes and relationships, whereas quantitative research may touch on correlations and causal relationships. Regardless of the methodology, in this section you need to highlight the overall key findings in relation to your research questions.

Typically, this section only requires one or two paragraphs , depending on how many research questions you have. Aim to be concise here, as you will unpack these findings in more detail later in the chapter. For now, a few lines that directly address your research questions are all that you need.

Some examples of the kind of language you’d use here include:

The data suggest that…
The data support/oppose the theory that…
The analysis identifies…

These are purely examples. What you present here will be completely dependent on your original research questions, so make sure that you are led by them .

Step 3: Interpret your results

Once you’ve restated your research problem and research question(s) and briefly presented your key findings, you can unpack your findings by interpreting your results. Remember: only include what you reported in your results section – don’t introduce new information.

From a structural perspective, it can be a wise approach to follow a similar structure in this chapter as you did in your results chapter. This would help improve readability and make it easier for your reader to follow your arguments. For example, if you structured you results discussion by qualitative themes, it may make sense to do the same here.

Alternatively, you may structure this chapter by research questions, or based on an overarching theoretical framework that your study revolved around. Every study is different, so you’ll need to assess what structure works best for you.

When interpreting your results, you’ll want to assess how your findings compare to those of the existing research (from your literature review chapter). Even if your findings contrast with the existing research, you need to include these in your discussion. In fact, those contrasts are often the most interesting findings . In this case, you’d want to think about why you didn’t find what you were expecting in your data and what the significance of this contrast is.

Here are a few questions to help guide your discussion:

How do your results relate with those of previous studies ?
If you get results that differ from those of previous studies, why may this be the case?
What do your results contribute to your field of research?
What other explanations could there be for your findings?

When interpreting your findings, be careful not to draw conclusions that aren’t substantiated . Every claim you make needs to be backed up with evidence or findings from the data (and that data needs to be presented in the previous chapter – results). This can look different for different studies; qualitative data may require quotes as evidence, whereas quantitative data would use statistical methods and tests. Whatever the case, every claim you make needs to be strongly backed up.

Step 4: Acknowledge the limitations of your study

The fourth step in writing up your discussion chapter is to acknowledge the limitations of the study. These limitations can cover any part of your study , from the scope or theoretical basis to the analysis method(s) or sample. For example, you may find that you collected data from a very small sample with unique characteristics, which would mean that you are unable to generalise your results to the broader population.

For some students, discussing the limitations of their work can feel a little bit self-defeating . This is a misconception, as a core indicator of high-quality research is its ability to accurately identify its weaknesses. In other words, accurately stating the limitations of your work is a strength, not a weakness . All that said, be careful not to undermine your own research. Tell the reader what limitations exist and what improvements could be made, but also remind them of the value of your study despite its limitations.

Step 5: Make recommendations for implementation and future research

Now that you’ve unpacked your findings and acknowledge the limitations thereof, the next thing you’ll need to do is reflect on your study in terms of two factors:

The practical application of your findings
Suggestions for future research

The first thing to discuss is how your findings can be used in the real world – in other words, what contribution can they make to the field or industry? Where are these contributions applicable, how and why? For example, if your research is on communication in health settings, in what ways can your findings be applied to the context of a hospital or medical clinic? Make sure that you spell this out for your reader in practical terms, but also be realistic and make sure that any applications are feasible.

The next discussion point is the opportunity for future research . In other words, how can other studies build on what you’ve found and also improve the findings by overcoming some of the limitations in your study (which you discussed a little earlier). In doing this, you’ll want to investigate whether your results fit in with findings of previous research, and if not, why this may be the case. For example, are there any factors that you didn’t consider in your study? What future research can be done to remedy this? When you write up your suggestions, make sure that you don’t just say that more research is needed on the topic, also comment on how the research can build on your study.

Step 6: Provide a concluding summary

Finally, you’ve reached your final stretch. In this section, you’ll want to provide a brief recap of the key findings – in other words, the findings that directly address your research questions . Basically, your conclusion should tell the reader what your study has found, and what they need to take away from reading your report.

When writing up your concluding summary, bear in mind that some readers may skip straight to this section from the beginning of the chapter. So, make sure that this section flows well from and has a strong connection to the opening section of the chapter.

Tips and tricks for an A-grade discussion chapter

Now that you know what the discussion chapter is , what to include and exclude , and how to structure it , here are some tips and suggestions to help you craft a quality discussion chapter.

When you write up your discussion chapter, make sure that you keep it consistent with your introduction chapter , as some readers will skip from the introduction chapter directly to the discussion chapter. Your discussion should use the same tense as your introduction, and it should also make use of the same key terms.
Don’t make assumptions about your readers. As a writer, you have hands-on experience with the data and so it can be easy to present it in an over-simplified manner. Make sure that you spell out your findings and interpretations for the intelligent layman.
Have a look at other theses and dissertations from your institution, especially the discussion sections. This will help you to understand the standards and conventions of your university, and you’ll also get a good idea of how others have structured their discussion chapters. You can also check out our chapter template .
Avoid using absolute terms such as “These results prove that…”, rather make use of terms such as “suggest” or “indicate”, where you could say, “These results suggest that…” or “These results indicate…”. It is highly unlikely that a dissertation or thesis will scientifically prove something (due to a variety of resource constraints), so be humble in your language.
Use well-structured and consistently formatted headings to ensure that your reader can easily navigate between sections, and so that your chapter flows logically and coherently.

If you have any questions or thoughts regarding this post, feel free to leave a comment below. Also, if you’re looking for one-on-one help with your discussion chapter (or thesis in general), consider booking a free consultation with one of our highly experienced Grad Coaches to discuss how we can help you.

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36 Comments

Thank you this is helpful!

This is very helpful to me… Thanks a lot for sharing this with us 😊

This has been very helpful indeed. Thank you.

This is actually really helpful, I just stumbled upon it. Very happy that I found it, thank you.

Me too! I was kinda lost on how to approach my discussion chapter. How helpful! Thanks a lot!

This is really good and explicit. Thanks

Thank you, this blog has been such a help.

Thank you. This is very helpful.

Dear sir/madame

Thanks a lot for this helpful blog. Really, it supported me in writing my discussion chapter while I was totally unaware about its structure and method of writing.

With regards

Syed Firoz Ahmad PhD, Research Scholar

I agree so much. This blog was god sent. It assisted me so much while I was totally clueless about the context and the know-how. Now I am fully aware of what I am to do and how I am to do it.

Thanks! This is helpful!

thanks alot for this informative website

Dear Sir/Madam,

Truly, your article was much benefited when i structured my discussion chapter.

Thank you very much!!!

This is helpful for me in writing my research discussion component. I have to copy this text on Microsoft word cause of my weakness that I cannot be able to read the text on screen a long time. So many thanks for this articles.

This was helpful

Thanks Jenna, well explained.

Thank you! This is super helpful.

Thanks very much. I have appreciated the six steps on writing the Discussion chapter which are (i) Restating the research problem and questions (ii) Summarising the key findings (iii) Interpreting the results linked to relating to previous results in positive and negative ways; explaining whay different or same and contribution to field of research and expalnation of findings (iv) Acknowledgeing limitations (v) Recommendations for implementation and future resaerch and finally (vi) Providing a conscluding summary

My two questions are: 1. On step 1 and 2 can it be the overall or you restate and sumamrise on each findings based on the reaerch question? 2. On 4 and 5 do you do the acknowlledgement , recommendations on each research finding or overall. This is not clear from your expalanattion.

Please respond.

This post is very useful. I’m wondering whether practical implications must be introduced in the Discussion section or in the Conclusion section?

Sigh, I never knew a 20 min video could have literally save my life like this. I found this at the right time!!!! Everything I need to know in one video thanks a mil ! OMGG and that 6 step!!!!!! was the cherry on top the cake!!!!!!!!!

Thanks alot.., I have gained much

This piece is very helpful on how to go about my discussion section. I can always recommend GradCoach research guides for colleagues.

Many thanks for this resource. It has been very helpful to me. I was finding it hard to even write the first sentence. Much appreciated.

Thanks so much. Very helpful to know what is included in the discussion section

this was a very helpful and useful information

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it is very helpfull article, and i will recommend it to my fellow students. Thank you.

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Powerful, thank you for sharing.

Wow! Just wow! God bless the day I stumbled upon you guys’ YouTube videos! It’s been truly life changing and anxiety about my report that is due in less than a month has subsided significantly!

Simplified explanation. Well done.

The presentation is enlightening. Thank you very much.

Thanks for the support and guidance

This has been a great help to me and thank you do much

I second that “it is highly unlikely that a dissertation or thesis will scientifically prove something”; although, could you enlighten us on that comment and elaborate more please?

Sure, no problem.

Scientific proof is generally considered a very strong assertion that something is definitively and universally true. In most scientific disciplines, especially within the realms of natural and social sciences, absolute proof is very rare. Instead, researchers aim to provide evidence that supports or rejects hypotheses. This evidence increases or decreases the likelihood that a particular theory is correct, but it rarely proves something in the absolute sense.

Dissertations and theses, as substantial as they are, typically focus on exploring a specific question or problem within a larger field of study. They contribute to a broader conversation and body of knowledge. The aim is often to provide detailed insight, extend understanding, and suggest directions for further research rather than to offer definitive proof. These academic works are part of a cumulative process of knowledge building where each piece of research connects with others to gradually enhance our understanding of complex phenomena.

Furthermore, the rigorous nature of scientific inquiry involves continuous testing, validation, and potential refutation of ideas. What might be considered a “proof” at one point can later be challenged by new evidence or alternative interpretations. Therefore, the language of “proof” is cautiously used in academic circles to maintain scientific integrity and humility.

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Guide to Writing the Results and Discussion Sections of a Scientific Article

A quality research paper has both the qualities of in-depth research and good writing ( Bordage, 2001 ). In addition, a research paper must be clear, concise, and effective when presenting the information in an organized structure with a logical manner ( Sandercock, 2013 ).

In this article, we will take a closer look at the results and discussion section. Composing each of these carefully with sufficient data and well-constructed arguments can help improve your paper overall.

Guide to writing a science research manuscript e-book download

The results section of your research paper contains a description about the main findings of your research, whereas the discussion section interprets the results for readers and provides the significance of the findings. The discussion should not repeat the results.

Let’s dive in a little deeper about how to properly, and clearly organize each part.

How to Organize the Results Section

Since your results follow your methods, you’ll want to provide information about what you discovered from the methods you used, such as your research data. In other words, what were the outcomes of the methods you used?

You may also include information about the measurement of your data, variables, treatments, and statistical analyses.

To start, organize your research data based on how important those are in relation to your research questions. This section should focus on showing major results that support or reject your research hypothesis. Include your least important data as supplemental materials when submitting to the journal.

The next step is to prioritize your research data based on importance – focusing heavily on the information that directly relates to your research questions using the subheadings.

The organization of the subheadings for the results section usually mirrors the methods section. It should follow a logical and chronological order.

Subheading organization

Subheadings within your results section are primarily going to detail major findings within each important experiment. And the first paragraph of your results section should be dedicated to your main findings (findings that answer your overall research question and lead to your conclusion) (Hofmann, 2013).

In the book “Writing in the Biological Sciences,” author Angelika Hofmann recommends you structure your results subsection paragraphs as follows:

Experimental purpose
Interpretation

Each subheading may contain a combination of ( Bahadoran, 2019 ; Hofmann, 2013, pg. 62-63):

Text: to explain about the research data
Figures: to display the research data and to show trends or relationships, for examples using graphs or gel pictures.
Tables: to represent a large data and exact value

Decide on the best way to present your data — in the form of text, figures or tables (Hofmann, 2013).

Data or Results?

Sometimes we get confused about how to differentiate between data and results . Data are information (facts or numbers) that you collected from your research ( Bahadoran, 2019 ).

Whereas, results are the texts presenting the meaning of your research data ( Bahadoran, 2019 ).

One mistake that some authors often make is to use text to direct the reader to find a specific table or figure without further explanation. This can confuse readers when they interpret data completely different from what the authors had in mind. So, you should briefly explain your data to make your information clear for the readers.

Common Elements in Figures and Tables

Figures and tables present information about your research data visually. The use of these visual elements is necessary so readers can summarize, compare, and interpret large data at a glance. You can use graphs or figures to compare groups or patterns. Whereas, tables are ideal to present large quantities of data and exact values.

Several components are needed to create your figures and tables. These elements are important to sort your data based on groups (or treatments). It will be easier for the readers to see the similarities and differences among the groups.

When presenting your research data in the form of figures and tables, organize your data based on the steps of the research leading you into a conclusion.

Common elements of the figures (Bahadoran, 2019):

Figure number
Figure title
Figure legend (for example a brief title, experimental/statistical information, or definition of symbols).

Tables in the result section may contain several elements (Bahadoran, 2019):

Table number
Table title
Row headings (for example groups)
Column headings
Row subheadings (for example categories or groups)
Column subheadings (for example categories or variables)
Footnotes (for example statistical analyses)

Tips to Write the Results Section

Direct the reader to the research data and explain the meaning of the data.
Avoid using a repetitive sentence structure to explain a new set of data.
Write and highlight important findings in your results.
Use the same order as the subheadings of the methods section.
Match the results with the research questions from the introduction. Your results should answer your research questions.
Be sure to mention the figures and tables in the body of your text.
Make sure there is no mismatch between the table number or the figure number in text and in figure/tables.
Only present data that support the significance of your study. You can provide additional data in tables and figures as supplementary material.

How to Organize the Discussion Section

It’s not enough to use figures and tables in your results section to convince your readers about the importance of your findings. You need to support your results section by providing more explanation in the discussion section about what you found.

In the discussion section, based on your findings, you defend the answers to your research questions and create arguments to support your conclusions.

Below is a list of questions to guide you when organizing the structure of your discussion section ( Viera et al ., 2018 ):

What experiments did you conduct and what were the results?
What do the results mean?
What were the important results from your study?
How did the results answer your research questions?
Did your results support your hypothesis or reject your hypothesis?
What are the variables or factors that might affect your results?
What were the strengths and limitations of your study?
What other published works support your findings?
What other published works contradict your findings?
What possible factors might cause your findings different from other findings?
What is the significance of your research?
What are new research questions to explore based on your findings?

Organizing the Discussion Section

The structure of the discussion section may be different from one paper to another, but it commonly has a beginning, middle-, and end- to the section.

One way to organize the structure of the discussion section is by dividing it into three parts (Ghasemi, 2019):

The beginning: The first sentence of the first paragraph should state the importance and the new findings of your research. The first paragraph may also include answers to your research questions mentioned in your introduction section.
The middle: The middle should contain the interpretations of the results to defend your answers, the strength of the study, the limitations of the study, and an update literature review that validates your findings.
The end: The end concludes the study and the significance of your research.

Another possible way to organize the discussion section was proposed by Michael Docherty in British Medical Journal: is by using this structure ( Docherty, 1999 ):

Discussion of important findings
Comparison of your results with other published works
Include the strengths and limitations of the study
Conclusion and possible implications of your study, including the significance of your study – address why and how is it meaningful
Future research questions based on your findings

Finally, a last option is structuring your discussion this way (Hofmann, 2013, pg. 104):

First Paragraph: Provide an interpretation based on your key findings. Then support your interpretation with evidence.
Secondary results
Limitations
Unexpected findings
Comparisons to previous publications
Last Paragraph: The last paragraph should provide a summarization (conclusion) along with detailing the significance, implications and potential next steps.

Remember, at the heart of the discussion section is presenting an interpretation of your major findings.

Tips to Write the Discussion Section

Highlight the significance of your findings
Mention how the study will fill a gap in knowledge.
Indicate the implication of your research.
Avoid generalizing, misinterpreting your results, drawing a conclusion with no supportive findings from your results.

Aggarwal, R., & Sahni, P. (2018). The Results Section. In Reporting and Publishing Research in the Biomedical Sciences (pp. 21-38): Springer.

Bahadoran, Z., Mirmiran, P., Zadeh-Vakili, A., Hosseinpanah, F., & Ghasemi, A. (2019). The principles of biomedical scientific writing: Results. International journal of endocrinology and metabolism, 17(2).

Bordage, G. (2001). Reasons reviewers reject and accept manuscripts: the strengths and weaknesses in medical education reports. Academic medicine, 76(9), 889-896.

Cals, J. W., & Kotz, D. (2013). Effective writing and publishing scientific papers, part VI: discussion. Journal of clinical epidemiology, 66(10), 1064.

Docherty, M., & Smith, R. (1999). The case for structuring the discussion of scientific papers: Much the same as that for structuring abstracts. In: British Medical Journal Publishing Group.

Faber, J. (2017). Writing scientific manuscripts: most common mistakes. Dental press journal of orthodontics, 22(5), 113-117.

Fletcher, R. H., & Fletcher, S. W. (2018). The discussion section. In Reporting and Publishing Research in the Biomedical Sciences (pp. 39-48): Springer.

Ghasemi, A., Bahadoran, Z., Mirmiran, P., Hosseinpanah, F., Shiva, N., & Zadeh-Vakili, A. (2019). The Principles of Biomedical Scientific Writing: Discussion. International journal of endocrinology and metabolism, 17(3).

Hofmann, A. H. (2013). Writing in the biological sciences: a comprehensive resource for scientific communication . New York: Oxford University Press.

Kotz, D., & Cals, J. W. (2013). Effective writing and publishing scientific papers, part V: results. Journal of clinical epidemiology, 66(9), 945.

Mack, C. (2014). How to Write a Good Scientific Paper: Structure and Organization. Journal of Micro/ Nanolithography, MEMS, and MOEMS, 13. doi:10.1117/1.JMM.13.4.040101

Moore, A. (2016). What's in a Discussion section? Exploiting 2‐dimensionality in the online world…. Bioessays, 38(12), 1185-1185.

Peat, J., Elliott, E., Baur, L., & Keena, V. (2013). Scientific writing: easy when you know how: John Wiley & Sons.

Sandercock, P. M. L. (2012). How to write and publish a scientific article. Canadian Society of Forensic Science Journal, 45(1), 1-5.

Teo, E. K. (2016). Effective Medical Writing: The Write Way to Get Published. Singapore Medical Journal, 57(9), 523-523. doi:10.11622/smedj.2016156

Van Way III, C. W. (2007). Writing a scientific paper. Nutrition in Clinical Practice, 22(6), 636-640.

Vieira, R. F., Lima, R. C. d., & Mizubuti, E. S. G. (2019). How to write the discussion section of a scientific article. Acta Scientiarum. Agronomy, 41.

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Writing a scientific paper.

Writing a lab report
INTRODUCTION

Writing a "good" discussion section

"discussion and conclusions checklist" from: how to write a good scientific paper. chris a. mack. spie. 2018., peer review.

LITERATURE CITED
Bibliography of guides to scientific writing and presenting
Presentations
Lab Report Writing Guides on the Web

This is is usually the hardest section to write. You are trying to bring out the true meaning of your data without being too long. Do not use words to conceal your facts or reasoning. Also do not repeat your results, this is a discussion.

Present principles, relationships and generalizations shown by the results
Point out exceptions or lack of correlations. Define why you think this is so.
Show how your results agree or disagree with previously published works
Discuss the theoretical implications of your work as well as practical applications
State your conclusions clearly. Summarize your evidence for each conclusion.
Discuss the significance of the results
Evidence does not explain itself; the results must be presented and then explained.
Typical stages in the discussion: summarizing the results, discussing whether results are expected or unexpected, comparing these results to previous work, interpreting and explaining the results (often by comparison to a theory or model), and hypothesizing about their generality.
Discuss any problems or shortcomings encountered during the course of the work.
Discuss possible alternate explanations for the results.
Avoid: presenting results that are never discussed; presenting discussion that does not relate to any of the results; presenting results and discussion in chronological order rather than logical order; ignoring results that do not support the conclusions; drawing conclusions from results without logical arguments to back them up.

CONCLUSIONS

Provide a very brief summary of the Results and Discussion.
Emphasize the implications of the findings, explaining how the work is significant and providing the key message(s) the author wishes to convey.
Provide the most general claims that can be supported by the evidence.
Provide a future perspective on the work.
Avoid: repeating the abstract; repeating background information from the Introduction; introducing new evidence or new arguments not found in the Results and Discussion; repeating the arguments made in the Results and Discussion; failing to address all of the research questions set out in the Introduction.

WHAT HAPPENS AFTER I COMPLETE MY PAPER?

The peer review process is the quality control step in the publication of ideas. Papers that are submitted to a journal for publication are sent out to several scientists (peers) who look carefully at the paper to see if it is "good science". These reviewers then recommend to the editor of a journal whether or not a paper should be published. Most journals have publication guidelines. Ask for them and follow them exactly. Peer reviewers examine the soundness of the materials and methods section. Are the materials and methods used written clearly enough for another scientist to reproduce the experiment? Other areas they look at are: originality of research, significance of research question studied, soundness of the discussion and interpretation, correct spelling and use of technical terms, and length of the article.

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Next: LITERATURE CITED >>
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8.2 An example template for Discussion sections

There’s no hard rule about what information types (d1 to d6) to include in each paragraph of the Discussion section. The only ‘rule’ is that the Discussion section of published papers contains all of the six information types ( Cargill M and O’Connor P 2013 Writing Scientific Research Articles: Strategy and Steps ), and your Discussion section probably should, too.

On Pages 5 to 6 of the following document is a template that I (Amanda) use to help me get started in writing the Discussion section of papers in my own field of research (obesity). The finished Discussion section is often different from the template below, so the template is more of a ‘kick-starter’ template than a bossy template.

You may like to use this template as an example from which to create a kick-starter template for writing the Discussion section of your own papers, based on your observations from dissection of Discussion sections you like from published papers in your field.

It’s possible that you already have a copy of the following document, as it was also included for download in Steps 2 and 8.

Photo by Zdeněk Macháček on Unsplash

Click here to download the document

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Research Paper Discussion Section

How To Write A Discussion For A Research Paper | Examples & Tips

What Exactly is a Discussion Section in the Research Paper?

In a research paper, the discussion section is where you explain what your results really mean. It's like answering the questions, "So what?" and "What's the big picture?"

The discussion section is your chance to help your readers understand why your findings are important and how they fit into the larger context. It's more than just summarizing; it's about making your research understandable and meaningful to others.

Importance of the Discussion Section

The discussion section isn't just a formality; it's the heart of your research paper. This is where your findings transform from data into knowledge.

Let's break down why it's so crucial:

Interpretation of Results : The discussion is where you get to tell readers what your results really mean. You go into the details, helping them understand the story behind the numbers or findings.
Connecting the Dots : You connect different parts of your research, showing how they relate. This helps your readers see the bigger picture.
Relevance to the Big Picture : You get to highlight why your research matters. How does it contribute to the broader understanding of the topic? This is your time to make your research significant.
Addressing Limitations : In the discussion, you can acknowledge any limitations in your study and discuss how they might impact your results.
Suggestions for Further Research : The discussion is where you suggest areas for future exploration. It's like passing the baton to the next researcher, indicating where more work could be done.

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How to Write the Discussion Section of a Research Paper?

The Discussion section in a research paper plays a vital role in interpreting findings and formulating a conclusion . Given below are the main components of the discussion section:

Quick Summary: A brief recap of your main findings.
Interpretation: Significance and meaning of your results in relation to your research question.
Literature Review : Connecting your findings with previous research or similar studies.
Limitations: Discussing any study limitations, addressing potential concerns.
Implications: Broader implications of your findings, considering practical and theoretical aspects.
Alternative Explanations: Evaluating alternative interpretations, demonstrating a comprehensive analysis.
Connecting to Hypotheses : Summarizing how your result section aligns or diverges from your initial hypotheses.

Now let’s explore the steps to write an effective discussion section that will effectively communicate the significance of your research:

Step 1: Get Started with a Quick Summary

Start by quickly telling your readers the main things you found in your research. Don't explain them in detail just yet; just give a simple overview.

This helps your readers get the big picture before diving into the details.

For instance, you conducted a study on the effects of exercise on mood. Your concise summary might look like this:

Step 2: Interpret Your Results

In the next step, talk about what your findings really mean. Share why the information you gathered is important. Connect each result to the questions you were trying to answer and the goals you set for your research.

You did research on whether plants grow better with different types of light. Here's how you interpret the results:

Step 3: Relate to Existing Literature

In this step, link up your discoveries with what other researchers have already figured out.

Share if your results are similar to or different from what's been found before. This helps give more background to your study and shows you know what other scientists have been up to.

You conducted a study on the impact of technology use on sleep patterns. Here’s how you can relate it to the existing knowledge or research:

Step 4: Address Limitations Honestly

Every study has its limitations. Acknowledge them openly in your discussion. This not only shows transparency but also helps readers interpret your results more accurately.

Let's consider a study on the effects of a new teaching method on student performance. You can address the limitations of the research like this:

Step 5: Discuss the Implications

Explore the implications of your findings. How do they contribute to the field? What real-world applications or changes might they suggest?

Dig into why your discoveries are important. How do they help the subject you studied?

This step is like looking at the bigger picture and asking, "So, what can we do with this information?"

Consider the example of a study on the impact of a new app on improving language learning; here’s how you can discuss your implications:

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Step 6: Consider Alternative Explanations

After discussing the implications, challenge yourself by exploring alternative explanations for your results.

Discuss different perspectives and show that you've considered multiple angles.

Consider the example of a study on the impact of a new study technique on exam performance. This is how you consider alternative explanations:

Step 7: Connect to Your Hypotheses or Research Questions

For the last step, revisit your initial hypotheses or research questions. Explain whether your results support what you thought might happen or if they surprised you.

For instance, in a study about the impact of a new teaching method on student engagement, you can connect hypotheses like this:

Examples of Good Discussion for a Research Paper

Learning from well-crafted discussions can significantly enhance your own writing. Given below are some examples to help you understand how to write your own.

Discussion for a Research Paper Example Pdf

Discussion for a Medical Research Paper

Discussion Section for a Qualitative Research Paper

Mistakes to Avoid in Your Research Paper's Discussion

Writing the discussion section of your research paper can be tricky. To make sure you're on the right track, be mindful of these common mistakes:

Overstating or Overinterpreting Results

Avoid making your findings sound more groundbreaking than they are. Stick to what your data actually shows, and don't exaggerate.

Neglecting Alternative Explanations

Failing to consider other possible explanations for your results can weaken your discussion. Always explore alternative perspectives to present a well-rounded view.

Ignoring Limitations

Don't sweep limitations under the rug. Acknowledge them openly and discuss how they might affect the validity or generalizability of your results.

Being Overly Technical or Jargon-laden

Remember that your audience may not be experts in your specific field. Avoid using overly technical language or excessive jargon that could alienate your readers.

Disregarding the 'So What' Factor

Always explain the significance of your findings. Don't leave your readers wondering why your research matters or how it contributes to the broader understanding of the subject.

Rushing the Conclusion

The conclusion section of your discussion is critical. Don't rush it. Summarize the key points and leave your readers with a strong understanding of the significance of your research.

So, there you have it —writing a discussion and conclusion section isn't easy, but avoiding some common mistakes can make it much smoother.

Remember to keep it real with your results, think about what else could explain things, and don't forget about any limits in your study.

But if you're feeling stuck, MyPerfectWords.com is here for you.

Our team of experts knows their way around discussions. Whether you need some guidance or want someone to handle the writing for you, we've got your back.

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General Research Paper Guidelines: Discussion

Discussion section.

The overall purpose of a research paper’s discussion section is to evaluate and interpret results, while explaining both the implications and limitations of your findings. Per APA (2020) guidelines, this section requires you to “examine, interpret, and qualify the results and draw inferences and conclusions from them” (p. 89). Discussion sections also require you to detail any new insights, think through areas for future research, highlight the work that still needs to be done to further your topic, and provide a clear conclusion to your research paper. In a good discussion section, you should do the following:

Clearly connect the discussion of your results to your introduction, including your central argument, thesis, or problem statement.
Provide readers with a critical thinking through of your results, answering the “so what?” question about each of your findings. In other words, why is this finding important?
Detail how your research findings might address critical gaps or problems in your field
Compare your results to similar studies’ findings
Provide the possibility of alternative interpretations, as your goal as a researcher is to “discover” and “examine” and not to “prove” or “disprove.” Instead of trying to fit your results into your hypothesis, critically engage with alternative interpretations to your results.

For more specific details on your Discussion section, be sure to review Sections 3.8 (pp. 89-90) and 3.16 (pp. 103-104) of your 7 th edition APA manual

*Box content adapted from:

University of Southern California (n.d.). Organizing your social sciences research paper: 8 the discussion . https://libguides.usc.edu/writingguide/discussion

Limitations

Limitations of generalizability or utility of findings, often over which the researcher has no control, should be detailed in your Discussion section. Including limitations for your reader allows you to demonstrate you have thought critically about your given topic, understood relevant literature addressing your topic, and chosen the methodology most appropriate for your research. It also allows you an opportunity to suggest avenues for future research on your topic. An effective limitations section will include the following:

Detail (a) sources of potential bias, (b) possible imprecision of measures, (c) other limitations or weaknesses of the study, including any methodological or researcher limitations.
Sample size: In quantitative research, if a sample size is too small, it is more difficult to generalize results.
Lack of available/reliable data : In some cases, data might not be available or reliable, which will ultimately affect the overall scope of your research. Use this as an opportunity to explain areas for future study.
Lack of prior research on your study topic: In some cases, you might find that there is very little or no similar research on your study topic, which hinders the credibility and scope of your own research. If this is the case, use this limitation as an opportunity to call for future research. However, make sure you have done a thorough search of the available literature before making this claim.
Flaws in measurement of data: Hindsight is 20/20, and you might realize after you have completed your research that the data tool you used actually limited the scope or results of your study in some way. Again, acknowledge the weakness and use it as an opportunity to highlight areas for future study.
Limits of self-reported data: In your research, you are assuming that any participants will be honest and forthcoming with responses or information they provide to you. Simply acknowledging this assumption as a possible limitation is important in your research.
Access: Most research requires that you have access to people, documents, organizations, etc.. However, for various reasons, access is sometimes limited or denied altogether. If this is the case, you will want to acknowledge access as a limitation to your research.
Time: Choosing a research focus that is narrow enough in scope to finish in a given time period is important. If such limitations of time prevent you from certain forms of research, access, or study designs, acknowledging this time restraint is important. Acknowledging such limitations is important, as they can point other researchers to areas that require future study.
Potential Bias: All researchers have some biases, so when reading and revising your draft, pay special attention to the possibilities for bias in your own work. Such bias could be in the form you organized people, places, participants, or events. They might also exist in the method you selected or the interpretation of your results. Acknowledging such bias is an important part of the research process.
Language Fluency: On occasion, researchers or research participants might have language fluency issues, which could potentially hinder results or how effectively you interpret results. If this is an issue in your research, make sure to acknowledge it in your limitations section.

University of Southern California (n.d.). Organizing your social sciences research paper: Limitations of the study . https://libguides.usc.edu/writingguide/limitations

In many research papers, the conclusion, like the limitations section, is folded into the larger discussion section. If you are unsure whether to include the conclusion as part of your discussion or as a separate section, be sure to defer to the assignment instructions or ask your instructor.

The conclusion is important, as it is specifically designed to highlight your research’s larger importance outside of the specific results of your study. Your conclusion section allows you to reiterate the main findings of your study, highlight their importance, and point out areas for future research. Based on the scope of your paper, your conclusion could be anywhere from one to three paragraphs long. An effective conclusion section should include the following:

Describe the possibilities for continued research on your topic, including what might be improved, adapted, or added to ensure useful and informed future research.
Provide a detailed account of the importance of your findings
Reiterate why your problem is important, detail how your interpretation of results impacts the subfield of study, and what larger issues both within and outside of your field might be affected from such results

University of Southern California (n.d.). Organizing your social sciences research paper: 9. the conclusion . https://libguides.usc.edu/writingguide/conclusion

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Organizing Academic Research Papers: 8. The Discussion

Purpose of Guide
Design Flaws to Avoid
Glossary of Research Terms
Narrowing a Topic Idea
Broadening a Topic Idea
Extending the Timeliness of a Topic Idea
Academic Writing Style
Choosing a Title
Making an Outline
Paragraph Development
Executive Summary
Background Information
The Research Problem/Question
Theoretical Framework
Citation Tracking
Content Alert Services
Evaluating Sources
Primary Sources
Secondary Sources
Tertiary Sources
What Is Scholarly vs. Popular?
Qualitative Methods
Quantitative Methods
Using Non-Textual Elements
Limitations of the Study
Common Grammar Mistakes
Avoiding Plagiarism
Footnotes or Endnotes?
Further Readings
Annotated Bibliography
Dealing with Nervousness
Using Visual Aids
Grading Someone Else's Paper
How to Manage Group Projects
Multiple Book Review Essay
Reviewing Collected Essays
About Informed Consent
Writing Field Notes
Writing a Policy Memo
Writing a Research Proposal
Acknowledgements

The purpose of the discussion is to interpret and describe the significance of your findings in light of what was already known about the research problem being investigated, and to explain any new understanding or fresh insights about the problem after you've taken the findings into consideration. The discussion will always connect to the introduction by way of the research questions or hypotheses you posed and the literature you reviewed, but it does not simply repeat or rearrange the introduction; the discussion should always explain how your study has moved the reader's understanding of the research problem forward from where you left them at the end of the introduction.

Importance of a Good Discussion

This section is often considered the most important part of a research paper because it most effectively demonstrates your ability as a researcher to think critically about an issue, to develop creative solutions to problems based on the findings, and to formulate a deeper, more profound understanding of the research problem you are studying.

The discussion section is where you explore the underlying meaning of your research , its possible implications in other areas of study, and the possible improvements that can be made in order to further develop the concerns of your research.

This is the section where you need to present the importance of your study and how it may be able to contribute to and/or fill existing gaps in the field. If appropriate, the discussion section is also where you state how the findings from your study revealed new gaps in the literature that had not been previously exposed or adequately described.

This part of the paper is not strictly governed by objective reporting of information but, rather, it is where you can engage in creative thinking about issues through evidence-based interpretation of findings. This is where you infuse your results with meaning.

Kretchmer, Paul. Fourteen Steps to Writing to Writing an Effective Discussion Section . San Francisco Edit, 2003-2008.

Structure and Writing Style

I. General Rules

These are the general rules you should adopt when composing your discussion of the results :

Do not be verbose or repetitive.
Be concise and make your points clearly.
Avoid using jargon.
Follow a logical stream of thought.
Use the present verb tense, especially for established facts; however, refer to specific works and references in the past tense.
If needed, use subheadings to help organize your presentation or to group your interpretations into themes.

II. The Content

The content of the discussion section of your paper most often includes :

Explanation of results : comment on whether or not the results were expected and present explanations for the results; go into greater depth when explaining findings that were unexpected or especially profound. If appropriate, note any unusual or unanticipated patterns or trends that emerged from your results and explain their meaning.
References to previous research : compare your results with the findings from other studies, or use the studies to support a claim. This can include re-visiting key sources already cited in your literature review section, or, save them to cite later in the discussion section if they are more important to compare with your results than being part of the general research you cited to provide context and background information.
Deduction : a claim for how the results can be applied more generally. For example, describing lessons learned, proposing recommendations that can help improve a situation, or recommending best practices.
Hypothesis : a more general claim or possible conclusion arising from the results [which may be proved or disproved in subsequent research].

III. Organization and Structure

Keep the following sequential points in mind as you organize and write the discussion section of your paper:

Think of your discussion as an inverted pyramid. Organize the discussion from the general to the specific, linking your findings to the literature, then to theory, then to practice [if appropriate].
Use the same key terms, mode of narration, and verb tense [present] that you used when when describing the research problem in the introduction.
Begin by briefly re-stating the research problem you were investigating and answer all of the research questions underpinning the problem that you posed in the introduction.
Describe the patterns, principles, and relationships shown by each major findings and place them in proper perspective. The sequencing of providing this information is important; first state the answer, then the relevant results, then cite the work of others. If appropriate, refer the reader to a figure or table to help enhance the interpretation of the data. The order of interpreting each major finding should be in the same order as they were described in your results section.
A good discussion section includes analysis of any unexpected findings. This paragraph should begin with a description of the unexpected finding, followed by a brief interpretation as to why you believe it appeared and, if necessary, its possible significance in relation to the overall study. If more than one unexpected finding emerged during the study, describe each them in the order they appeared as you gathered the data.
Before concluding the discussion, identify potential limitations and weaknesses. Comment on their relative importance in relation to your overall interpretation of the results and, if necessary, note how they may affect the validity of the findings. Avoid using an apologetic tone; however, be honest and self-critical.
The discussion section should end with a concise summary of the principal implications of the findings regardless of statistical significance. Give a brief explanation about why you believe the findings and conclusions of your study are important and how they support broader knowledge or understanding of the research problem. This can be followed by any recommendations for further research. However, do not offer recommendations which could have been easily addressed within the study. This demonstrates to the reader you have inadequately examined and interpreted the data.

IV. Overall Objectives

The objectives of your discussion section should include the following: I. Reiterate the Research Problem/State the Major Findings

Briefly reiterate for your readers the research problem or problems you are investigating and the methods you used to investigate them, then move quickly to describe the major findings of the study. You should write a direct, declarative, and succinct proclamation of the study results.

II. Explain the Meaning of the Findings and Why They are Important

No one has thought as long and hard about your study as you have. Systematically explain the meaning of the findings and why you believe they are important. After reading the discussion section, you want the reader to think about the results [“why hadn’t I thought of that?”]. You don’t want to force the reader to go through the paper multiple times to figure out what it all means. Begin this part of the section by repeating what you consider to be your most important finding first.

III. Relate the Findings to Similar Studies

No study is so novel or possesses such a restricted focus that it has absolutely no relation to other previously published research. The discussion section should relate your study findings to those of other studies, particularly if questions raised by previous studies served as the motivation for your study, the findings of other studies support your findings [which strengthens the importance of your study results], and/or they point out how your study differs from other similar studies. IV. Consider Alternative Explanations of the Findings

It is important to remember that the purpose of research is to discover and not to prove . When writing the discussion section, you should carefully consider all possible explanations for the study results, rather than just those that fit your prior assumptions or biases.

V. Acknowledge the Study’s Limitations

It is far better for you to identify and acknowledge your study’s limitations than to have them pointed out by your professor! Describe the generalizability of your results to other situations, if applicable to the method chosen, then describe in detail problems you encountered in the method(s) you used to gather information. Note any unanswered questions or issues your study did not address, and.... VI. Make Suggestions for Further Research

Although your study may offer important insights about the research problem, other questions related to the problem likely remain unanswered. Moreover, some unanswered questions may have become more focused because of your study. You should make suggestions for further research in the discussion section.

NOTE: Besides the literature review section, the preponderance of references to sources in your research paper are usually found in the discussion section . A few historical references may be helpful for perspective but most of the references should be relatively recent and included to aid in the interpretation of your results and/or linked to similar studies. If a study that you cited disagrees with your findings, don't ignore it--clearly explain why the study's findings differ from yours.

V. Problems to Avoid

Do not waste entire sentences restating your results . Should you need to remind the reader of the finding to be discussed, use "bridge sentences" that relate the result to the interpretation. An example would be: “The lack of available housing to single women with children in rural areas of Texas suggests that...[then move to the interpretation of this finding].”
Recommendations for further research can be included in either the discussion or conclusion of your paper but do not repeat your recommendations in the both sections.
Do not introduce new results in the discussion. Be wary of mistaking the reiteration of a specific finding for an interpretation.
Use of the first person is acceptable, but too much use of the first person may actually distract the reader from the main points.

Analyzing vs. Summarizing. Department of English Writing Guide. George Mason University; Discussion . The Structure, Format, Content, and Style of a Journal-Style Scientific Paper. Department of Biology. Bates College; Hess, Dean R. How to Write an Effective Discussion. Respiratory Care 49 (October 2004); Kretchmer, Paul. Fourteen Steps to Writing to Writing an Effective Discussion Section . San Francisco Edit, 2003-2008; The Lab Report . University College Writing Centre. University of Toronto; Summary: Using it Wisely . The Writing Center. University of North Carolina; Schafer, Mickey S. Writing the Discussion . Writing in Psychology course syllabus. University of Florida; Yellin, Linda L. A Sociology Writer's Guide. Boston, MA: Allyn and Bacon, 2009.

Writing Tip

Don’t Overinterpret the Results!

Interpretation is a subjective exercise. Therefore, be careful that you do not read more into the findings than can be supported by the evidence you've gathered. Remember that the data are the data: nothing more, nothing less.

Another Writing Tip

Don't Write Two Results Sections!

Azar, Beth. Discussing Your Findings. American Psychological Association gradPSYCH Magazine (January 2006)

Yet Another Writing Tip

Avoid Unwarranted Speculation!

The discussion section should remain focused on the findings of your study. For example, if you studied the impact of foreign aid on increasing levels of education among the poor in Bangladesh, it's generally not appropriate to speculate about how your findings might apply to populations in other countries without drawing from existing studies to support your claim. If you feel compelled to speculate, be certain that you clearly identify your comments as speculation or as a suggestion for where further research is needed. Sometimes your professor will encourage you to expand the discussion in this way, while others don’t care what your opinion is beyond your efforts to interpret the data.

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Next: Limitations of the Study >>
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10 Research Question Examples to Guide Your Research Project

10 Research Question Examples to Guide your Research Project

Published on October 30, 2022 by Shona McCombes . Revised on October 19, 2023.

The research question is one of the most important parts of your research paper , thesis or dissertation . It’s important to spend some time assessing and refining your question before you get started.

The exact form of your question will depend on a few things, such as the length of your project, the type of research you’re conducting, the topic , and the research problem . However, all research questions should be focused, specific, and relevant to a timely social or scholarly issue.

Once you’ve read our guide on how to write a research question , you can use these examples to craft your own.

Research question	Explanation
	The first question is not enough. The second question is more , using .
	Starting with “why” often means that your question is not enough: there are too many possible answers. By targeting just one aspect of the problem, the second question offers a clear path for research.
	The first question is too broad and subjective: there’s no clear criteria for what counts as “better.” The second question is much more . It uses clearly defined terms and narrows its focus to a specific population.
	It is generally not for academic research to answer broad normative questions. The second question is more specific, aiming to gain an understanding of possible solutions in order to make informed recommendations.
	The first question is too simple: it can be answered with a simple yes or no. The second question is , requiring in-depth investigation and the development of an original argument.
	The first question is too broad and not very . The second question identifies an underexplored aspect of the topic that requires investigation of various to answer.
	The first question is not enough: it tries to address two different (the quality of sexual health services and LGBT support services). Even though the two issues are related, it’s not clear how the research will bring them together. The second integrates the two problems into one focused, specific question.
	The first question is too simple, asking for a straightforward fact that can be easily found online. The second is a more question that requires and detailed discussion to answer.
? dealt with the theme of racism through casting, staging, and allusion to contemporary events?	The first question is not — it would be very difficult to contribute anything new. The second question takes a specific angle to make an original argument, and has more relevance to current social concerns and debates.
	The first question asks for a ready-made solution, and is not . The second question is a clearer comparative question, but note that it may not be practically . For a smaller research project or thesis, it could be narrowed down further to focus on the effectiveness of drunk driving laws in just one or two countries.

Note that the design of your research question can depend on what method you are pursuing. Here are a few options for qualitative, quantitative, and statistical research questions.

Type of research	Example question
Qualitative research question
Quantitative research question
Statistical research question

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How to Write a Discussion Section | Tips & Examples

How to Write a Discussion Section | Tips & Examples

Published on 21 August 2022 by Shona McCombes . Revised on 25 October 2022.

The discussion section is where you delve into the meaning, importance, and relevance of your results .

It should focus on explaining and evaluating what you found, showing how it relates to your literature review , and making an argument in support of your overall conclusion . It should not be a second results section .

There are different ways to write this section, but you can focus your writing around these key elements:

Summary: A brief recap of your key results
Interpretations: What do your results mean?
Implications: Why do your results matter?
Limitations: What can’t your results tell us?
Recommendations: Avenues for further studies or analyses

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What not to include in your discussion section, step 1: summarise your key findings, step 2: give your interpretations, step 3: discuss the implications, step 4: acknowledge the limitations, step 5: share your recommendations, discussion section example.

There are a few common mistakes to avoid when writing the discussion section of your paper.

Don’t introduce new results: You should only discuss the data that you have already reported in your results section .
Don’t make inflated claims: Avoid overinterpretation and speculation that isn’t directly supported by your data.
Don’t undermine your research: The discussion of limitations should aim to strengthen your credibility, not emphasise weaknesses or failures.

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Start this section by reiterating your research problem and concisely summarising your major findings. Don’t just repeat all the data you have already reported – aim for a clear statement of the overall result that directly answers your main research question . This should be no more than one paragraph.

Many students struggle with the differences between a discussion section and a results section . The crux of the matter is that your results sections should present your results, and your discussion section should subjectively evaluate them. Try not to blend elements of these two sections, in order to keep your paper sharp.

The results indicate that …
The study demonstrates a correlation between …
This analysis supports the theory that …
The data suggest that …

The meaning of your results may seem obvious to you, but it’s important to spell out their significance for your reader, showing exactly how they answer your research question.

The form of your interpretations will depend on the type of research, but some typical approaches to interpreting the data include:

Identifying correlations , patterns, and relationships among the data
Discussing whether the results met your expectations or supported your hypotheses
Contextualising your findings within previous research and theory
Explaining unexpected results and evaluating their significance
Considering possible alternative explanations and making an argument for your position

You can organise your discussion around key themes, hypotheses, or research questions, following the same structure as your results section. Alternatively, you can also begin by highlighting the most significant or unexpected results.

In line with the hypothesis …
Contrary to the hypothesised association …
The results contradict the claims of Smith (2007) that …
The results might suggest that x . However, based on the findings of similar studies, a more plausible explanation is x .

As well as giving your own interpretations, make sure to relate your results back to the scholarly work that you surveyed in the literature review . The discussion should show how your findings fit with existing knowledge, what new insights they contribute, and what consequences they have for theory or practice.

Ask yourself these questions:

Do your results support or challenge existing theories? If they support existing theories, what new information do they contribute? If they challenge existing theories, why do you think that is?
Are there any practical implications?

Your overall aim is to show the reader exactly what your research has contributed, and why they should care.

These results build on existing evidence of …
The results do not fit with the theory that …
The experiment provides a new insight into the relationship between …
These results should be taken into account when considering how to …
The data contribute a clearer understanding of …
While previous research has focused on x , these results demonstrate that y .

Even the best research has its limitations. Acknowledging these is important to demonstrate your credibility. Limitations aren’t about listing your errors, but about providing an accurate picture of what can and cannot be concluded from your study.

Limitations might be due to your overall research design, specific methodological choices , or unanticipated obstacles that emerged during your research process.

Here are a few common possibilities:

If your sample size was small or limited to a specific group of people, explain how generalisability is limited.
If you encountered problems when gathering or analysing data, explain how these influenced the results.
If there are potential confounding variables that you were unable to control, acknowledge the effect these may have had.

After noting the limitations, you can reiterate why the results are nonetheless valid for the purpose of answering your research question.

The generalisability of the results is limited by …
The reliability of these data is impacted by …
Due to the lack of data on x , the results cannot confirm …
The methodological choices were constrained by …
It is beyond the scope of this study to …

Based on the discussion of your results, you can make recommendations for practical implementation or further research. Sometimes, the recommendations are saved for the conclusion .

Suggestions for further research can lead directly from the limitations. Don’t just state that more studies should be done – give concrete ideas for how future work can build on areas that your own research was unable to address.

Further research is needed to establish …
Future studies should take into account …
Avenues for future research include …

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McCombes, S. (2022, October 25). How to Write a Discussion Section | Tips & Examples. Scribbr. Retrieved 2 July 2024, from https://www.scribbr.co.uk/thesis-dissertation/discussion/

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Research Article

Pharmacological and behavioral investigation of putative self-medicative plants in Budongo chimpanzee diets

Contributed equally to this work with: Elodie Freymann, Fabien Schultz

Roles Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Project administration, Resources, Visualization, Writing – original draft, Writing – review & editing

* E-mail: [email protected] (EF); [email protected] (FS)

Affiliation Primate Models for Behavioural Evolution Lab, Institute of Human Sciences, Department of Anthropology and Museum Ethnography, University of Oxford, Oxford, United Kingdom

Roles Supervision, Writing – review & editing

Affiliations Primate Models for Behavioural Evolution Lab, Institute of Human Sciences, Department of Anthropology and Museum Ethnography, University of Oxford, Oxford, United Kingdom, Gorongosa National Park, Sofala, Mozambique, Interdisciplinary Centre for Archaeology and the Evolution of Human Behaviour, University of Algarve, Faro, Portugal

Roles Funding acquisition, Supervision, Writing – review & editing

Affiliations Ethnopharmacology & Zoopharmacognosy Research Group, Department of Agriculture and Food Sciences, Neubrandenburg University of Applied Sciences, Neubrandenburg, Germany, ZELT–Center for Nutrition and Food Technology gGmbH

Roles Formal analysis, Writing – original draft, Writing – review & editing

Affiliation Ethnopharmacology & Zoopharmacognosy Research Group, Department of Agriculture and Food Sciences, Neubrandenburg University of Applied Sciences, Neubrandenburg, Germany

Roles Resources, Supervision, Writing – review & editing

Affiliations Wild Minds Lab, School of Psychology and Neuroscience, University of St Andrews, St Andrews, United Kingdom, Budongo Conservation Field Station, Masindi, Uganda

Affiliation Wildlife Research Center, Inuyama Campus, Kyoto University, Inuyama, Japan

Roles Investigation

Affiliation Budongo Conservation Field Station, Masindi, Uganda

Roles Formal analysis

Affiliations Budongo Conservation Field Station, Masindi, Uganda, Czech University of Life Sciences Prague, Prague, Czech Republic

Roles Resources, Writing – review & editing

Affiliations Budongo Conservation Field Station, Masindi, Uganda, Department of Comparative Cognition, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland

Roles Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Project administration, Resources, Writing – original draft, Writing – review & editing

Affiliations Ethnopharmacology & Zoopharmacognosy Research Group, Department of Agriculture and Food Sciences, Neubrandenburg University of Applied Sciences, Neubrandenburg, Germany, Pharmacognosy and Phytotherapy, School of Pharmacy, University College of London, London, United Kingdom

Elodie Freymann,
Susana Carvalho,
Leif A. Garbe,
Dinda Dwi Ghazhelia,
Catherine Hobaiter,
Michael A. Huffman,
Geresomu Muhumuza,
Lena Schulz,
Daniel Sempebwa,

Published: June 20, 2024
https://doi.org/10.1371/journal.pone.0305219
Reader Comments

Wild chimpanzees consume a variety of plants to meet their dietary needs and maintain wellbeing. While some plants have obvious value, others are nutritionally poor and/or contain bioactive toxins which make ingestion costly. In some cases, these nutrient-poor resources are speculated to be medicinal, thought to help individuals combat illness. In this study, we observed two habituated chimpanzee communities living in the Budongo Forest, Uganda, and collected 17 botanical samples associated with putative self-medication behaviors (e.g., bark feeding, dead wood eating, and pith-stripping) or events (e.g., when consumer had elevated parasite load, abnormal urinalysis, or injury). In total, we selected plant parts from 13 species (nine trees and four herbaceous plants). Three extracts of different polarities were produced from each sample using n -hexane, ethyl acetate, and methanol/water (9/1, v/v ) and introduced to antibacterial and anti-inflammatory in vitro models. Extracts were evaluated for growth inhibition against a panel of multidrug-resistant clinical isolates of bacteria, including ESKAPE strains and cyclooxygenase-2 (COX-2) inhibition activity. Pharmacological results suggest that Budongo chimpanzees consume several species with potent medicinal properties. In the antibacterial library screen, 45 out of 53 extracts (88%) exhibited ≥40% inhibition at a concentration of 256 μg/mL. Of these active extracts, 41 (91%) showed activity at ≤256μg/mL in subsequent dose-response antibacterial experiments. The strongest antibacterial activity was achieved by the n- hexane extract of Alstonia boonei dead wood against Staphylococcus aureus (IC50: 16 μg/mL; MIC: 32 μg/mL) and Enterococcus faecium (IC50: 16 μg/mL; MIC: >256 μg/mL) and by the methanol-water extract of Khaya anthotheca bark and resin against E . faecium (IC50: 16 μg/mL; MIC: 32 μg/mL) and pathogenic Escherichia coli (IC50: 16 μg/mL; MIC: 256 μg/mL). We observed ingestion of both these species by highly parasitized individuals. K . anthotheca bark and resin were also targeted by individuals with indicators of infection and injuries. All plant species negatively affected growth of E . coli . In the anti-inflammatory COX-2 inhibition library screen, 17 out of 51 tested extracts (33%) showed ≥50% COX-2 inhibition at a concentration of 5 μg/mL. Several extracts also exhibited anti-inflammatory effects in COX-2 dose-response experiments. The K . anthotheca bark and resin methanol-water extract showed the most potent effects (IC50: 0.55 μg/mL), followed by the fern Christella parasitica methanol-water extract (IC50: 0.81 μg/mL). This fern species was consumed by an injured individual, a feeding behavior documented only once before in this population. These results, integrated with associated observations from eight months of behavioral data, provide further evidence for the presence of self-medicative resources in wild chimpanzee diets. This study addresses the challenge of distinguishing preventative medicinal food consumption from therapeutic self-medication by integrating pharmacological, observational, and health monitoring data—an essential interdisciplinary approach for advancing the field of zoopharmacognosy.

Citation: Freymann E, Carvalho S, Garbe LA, Dwi Ghazhelia D, Hobaiter C, Huffman MA, et al. (2024) Pharmacological and behavioral investigation of putative self-medicative plants in Budongo chimpanzee diets. PLoS ONE 19(6): e0305219. https://doi.org/10.1371/journal.pone.0305219

Editor: Armel Jackson Seukep, University of Buea, CAMEROON

Received: January 9, 2024; Accepted: May 25, 2024; Published: June 20, 2024

Copyright: © 2024 Freymann et al. This is an open access article distributed under the terms of the Creative Commons Attribution License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Data Availability: All relevant data are within the manuscript and its Supporting Information files.

Funding: Funding for this project was granted by the the Clarendon Fund at the University of Oxford (to EF), the British Institute of Eastern Africa (to EF), Keble College at the University of Oxford (to EF), Boise Trust Fund (to EF), German Federal Ministry of Education and Research (13FH026IX5, PI: L-AG and Co-I: FS) (to LAG, FS) and Neubrandenburg University of Applied Sciences (grant # 13310510) (to LAG, FS).

Competing interests: The authors have declared that no competing interests exist.

Introduction

‘Medicinal foods’ refer to resources in the diet that have potential curative value due to the presence of plant secondary metabolites (PSMs) [ 1 , 2 ]. PSMs are compounds that usually occur only in special, differentiated cells [ 3 ] and which help plants defend against predators, pathogens, and competitors [ 4 – 7 ]. PSMs can have a range of functions, including the inhibition of microbial, fungal, and competitor growth [ 8 ]. While some PSMs can be toxic at high doses, these compounds can also promote the health of human and non-human consumers [ 8 – 10 ]. Research suggests 15–25% of primate and other mammalian diets consist of medicinal foods [ 9 , 11 ]. These resources likely play a critical role in animal health-maintenance by passively preventing or reducing the impact of parasitic infections or other pathogens [ 9 – 14 ].

While most animals likely consume foods with medicinal properties as part of their normal diets, fewer species have been shown to engage in therapeutic self-medication. Huffman [ 15 ] defines this type of self-medicative behavior as the active extraction and ingestion, by an ill individual, of medicinal resources with little nutritional value. Instead of an individual passively benefiting from a plant’s medicinal properties through normal feeding, this form of self-medication requires basic awareness of the resource’s healing properties. One of the best-studied animals to engage in this form of self-medication is our closest living relative: the chimpanzee.

Wild chimpanzees ( Pan troglodytes ), across at least sixteen field sites [ 15 ] have demonstrated therapeutic self-medication using two well-established self-medicative behaviors: leaf swallowing [ 16 , 17 ] and bitter-pith chewing [ 18 ]. Leaf swallowing, first reported by Wrangham [ 19 , 20 ] and described by Wrangham & Nishida [ 21 ], involves the careful selection and ingestion of whole, hispid leaves. This behavior was later demonstrated to expel internal parasites (i.e. Oesophagostomum sp. and Bertiella studeri ) from the gut [ 16 , 17 , 22 , 23 ]. The functional mechanism responsible for this anthelminthic effect is considered to be primarily “mechanical” [ 9 ] as, rather than a chemical compound, the leaf’s indigestibility, brought about by the trichomes on its surface—stimulates gut motility in the swallower [ 17 , 23 , 24 ].

The second established behavior is bitter-pith chewing, which involves the stripping of outer bark and leaves from the soft new stem growth of the shrub, Vernonia amygdalina , exposing the inner pith. Individuals chew the pith and ingest only the bitter juices while spitting out the fibers [ 18 , 25 ]. Bitter-pith chewing is considered ‘phytochemical’ self-medication [ 9 ], as its anthelminthic effect appears to be the result of bioactive PSMs [ 26 – 29 ]. This behavior’s medicinal effect was associated with a significant drop in the infection intensity of Oesophagostomum stephanostomum nematodes [ 25 ], suggesting that the bitter compounds directly affect the adult worms. This hypothesis was supported by in vivo studies conducted by Jisaka et al. [ 30 ], demonstrating that extracts from the pith permanently paralyzed adult Schistosome parasites. V . amygdalina is also used to aid gastrointestinal discomfort and other signs of parasitosis in humans and livestock, symptoms also displayed by chimpanzees ingesting the plant’s bitter pith [ 9 , 18 , 25 , 31 ]. The bitter piths of other plant species are reported to be chewed by chimpanzees across field sites but detailed studies on their medicinal properties have yet to be conducted [ 9 ].

Beyond these two established behaviors, not much is known about the phytochemical self-medicative repertoires of wild chimpanzees, although some behaviors associated with the ingestion of specific plant parts or processing techniques have been recommended for further investigation [ 9 , 15 , 32 ]. One of these behaviors is bark feeding, which involves the ingestion of living stem bark and/or cambium [ 33 ], and which has been observed in at least eleven established field sites [ 33 – 43 ]. Bark feeding has been suggested as a medicinal behavior in chimpanzees and other primates, used to aid in the chemical control of intestinal nematode infection and to relieve gastrointestinal upset [ 9 ]. Bark is characteristically highly fibrous, heavily lignified, sometimes toxic, relatively indigestible, and nutrient-poor [ 44 ]. However, the contribution of bark in chimpanzee diets and toward general health is still poorly understood [though see: 45 ]. In this study, the bark of eight species ingested by Budongo chimpanzees ( Scutia myrtina , Cynometra alexandri , Alstonia boonei , Ficus exasperata , Ficus variifolia , Syzygium guineense , Desplatsia dewevrei , Khaya anthotheca) was screened for antibiotic and anti-inflammatory properties, to better understand the function of bark feeding behaviors and the role this behavior may play in the health maintenance of chimpanzees. For the species K . anthotheca , we tested a mixture of bark and congealed resin, which Budongo chimpanzees were observed to particularly target throughout the study period.

Another putative self-medicative behavior is dead wood eating [ 9 , 35 ], which involves the consumption of decomposing cambium from dead trees. To date, the majority of studies examining this behavior in apes have focused on exploring potential mineral and nutritional benefits, rather than investigating pharmacological properties [ 46 – 49 ]. Many of these studies suggest that dead wood is exploited by chimpanzees as a source of sodium in environments where this mineral is otherwise scarce [ 48 , 49 ]. Our study evaluates the pharmacology of two species of dead wood ( A . boonei and Cleistopholis patens) consumed by the Sonso community of chimpanzees to determine whether this behavior may have multiple functions or health benefits.

The ingestion of pith material from other species has also been suggested as putatively self-medicative [ 34 , 50 , 51 ]. However, unlike V . amygdalina bitter-pith, some of these plant piths appear bland or tasteless. While Wrangham et al. have previously suggested that pith is likely a high-fiber fallback food [ 52 ], De la Fuente et al. review several pith species targeted by chimpanzees with proposed medicinal properties [ 32 ]. In our study, two species of non-bitter piths ( Marantachloa leucantha and Acanthus polystachyus) , were collected for pharmacological assessment. M . leucantha was observed on several occasions being stripped, masticated, and spat out after the juice was extracted from the pith, whereas A . polystachyus was observed being stripped, masticated, and swallowed. Both of these species are also ingested by chimpanzees in Kibale National Park, Uganda [ 52 ].

Establishing phytochemical self-medicative behaviors in wild animals is difficult and time consuming, as the burden of proof is high, self-medicative events can be rare relative to other behaviors, and methods often require multidisciplinary expertise and collaboration [ 9 ]. Past studies have utilized ethnopharmacological methods to determine specific medicinal properties of foods consumed by primates [ 11 ], greatly advancing our understanding of the relationship between primate diets and health. However, a key challenge for establishing novel self-medicative behaviors is differentiating between medicinal food consumption and therapeutic self-medication. While pharmacological data interpreted on its own is crucial for establishing the presence of medicinal resources in chimpanzee diets, the integration of observational and health monitoring data is needed to parse therapeutic self-medicative behaviors from normal feeding behaviors with inadvertent health benefits. Furthermore, the importance of collecting in situ samples from the locations where putative self-medicative behaviors are observed is paramount, as ecological, climatic, and anthropogenic variables can cause variation in the bioactivity of plants across habitats [ 53 ].

In total, we investigated the bioactivity of 51 plant extracts produced from 17 part-specific samples (across 13 species), collected in the Budongo Forest. Each extract was tested for inhibition of bacterial growth as well as anti-inflammatory COX-2 inhibition activity. Due to limitations in scope, funding, and the unavailability of anthelminthic assays for wild animal parasites, none were not conducted in this study, restricting specific identification of parasiticidal behaviors. Assay results are reported and contextualized in this study with direct behavioral evidence and health monitoring data.

Materials and method

Study site and subjects.

Behavioral data, health monitoring metrics, and botanical samples were collected from the Budongo Central Forest Reserve in Uganda (1°35′– 1°55′ N, 31°18′–31°42′ E). An overview of methodological workflow can be found in S2 Fig . The Budongo Conservation Field Station (BCFS) site, founded in 1990, is composed of continuous, semi-deciduous forest and contains two habituated Eastern chimpanzee ( Pan troglodytes schweinfurthii ) communities [ 54 ]. The Sonso community has been studied continuously since 1992, and the ages, social relationships, demographics, and diet of its members are well documented [ 55 , 56 ]. The Sonso population was ~68 individuals at the time of data collection, and the home range covered an area of ~5.33 km 2 [ 57 ]. Waibira, a larger group of at least 105 individuals, was more recently habituated, with consistent data collection beginning in 2011. The Waibira maximum home range area was ~10.28 km 2 [ 57 ].

Behavioral data collection

All samples were collected in the Budongo Forest within the Sonso home range, based on behavioral observations from the study period and supporting evidence from the site’s long-term data of their use. Behavioral and health data were collected from two neighboring chimpanzee communities, each for one four-month field season (Sonso: June-October 2021, Waibira: June-October 2022). Data collected between June-September 2021 informed subsequent plant sample collection for pharmacological analysis, which occurred in early September 2021. Behavioral data collected after sample collection provided additional behavioral context for ingestion of these species. Behavioral data were collected between 07:00 and 16:30 in Sonso and between 06:30 and 17:00 in Waibira using day-long focal animal follows sensu Altman et al. [ 58 ]. This data was recorded using Animal Observer (AO) on iPad and ad libitum feeding events were recorded for any unusual feeding behaviors, including but not limited to bark ingestion, dead wood eating, pith stripping, and geophagy. All feeding events were filmed on a Sony Handycam CX250. We prioritized focal follows on individuals with wounds, high or diverse parasite loads identified through on-going monitoring, or known ailments. However, consecutive day follows of priority individuals were not always possible—or were avoided when they might contribute to increased stress in particularly vulnerable individuals. Throughout the study, using this protocol, 27 Sonso individuals (♂:11; ♀:16) and 24 Waibira individuals (♂:14; ♀:10) were observed. Authors collecting behavioral data were blind to pharmacological results during both study periods.

Health monitoring

Individual health data were recorded in both communities, including opportunistic macroscopic and microscopic fecal analysis and urinalysis testing. While anthelminthic assays were not run in this study, parasite load was opportunistically assessed to provide additional health context for each observation. As the presence of certain helminths may impair a host’s immunological response to bacterial, viral, and protozoal pathogens [ 59 ], parasite load can provide a proxy measurement for overall health. Similarly, a reduced immune system and increased stress caused by co-infections could render a host more susceptible to virulent endoparasites [ 60 , 61 ]. When helminths and/or proglottids were found in samples, they were collected and preserved in ethanol for later identification. To quantify parasite loads, fecal samples were analyzed using the McMaster Method [ 9 , 25 , 62 ]. Urinalysis samples were taken opportunistically using multi-reagent Urine Dipstick Test 9-RC for Urotron RL9 to assess the health and physiological status of group members following methods established by Kaur & Huffman [ 63 ]. Urinalysis metrics considered in this study included: leukocytes (LEU) associated with pyuria caused by UTI, balanitis, urethritis, tuberculosis, bladder tumors, viral infections, nephrolithiasis, foreign bodies, exercise, glomerulonephritis, and corticosteroid and cyclophosphamide use; blood (BLO) associated with peroxidase activity of erythrocytes, and UTIs; and ketones (KET) associated with pregnancy, carbohydrate-free diets, starvation, and diabetes [ 64 ]. Test results were interpreted in situ using a colorimetric scale. We considered a result ‘abnormal’ if the colorimetric scale indicated a positive result when the expected result was negative or if the result was outside the specified test parameters according to the manufacturer.

Plant sample selection for bioactivity testing

Plants were selected for pharmacological testing after three months of data collection in the Sonso community. We selected 10 samples (from 9 species) based on direct observations during this period. These observations included individuals targeting plant parts associated with putative self-medicative behaviors (i.e., bark feeding, dead wood eating, pith-stripping) or sick/wounded individuals seeking out unusually consumed resources. We then selected an additional five species, the ingestion of which had not been directly observed, for testing based on their historical inclusion in Sonso chimpanzees’ bark feeding repertoire. GM, who has worked at the field station for over thirty-years, has previously observed bark feeding on each of these selected species. These historic observations enabled collection of bark samples from specific trees known to have been previously stripped. In two cases, leaf samples were collected from tree species that were also selected for bark samples ( S . guineense and F . exasperata) . While neither Sonso nor Waibira chimpanzees have been observed ingesting the leaves of S . guineense , a sample was collected to enable comparison of bioactivity across plant parts. F . exasperata leaves are consumed in both communities; however, we found no behavioral evidence for use in unusual contexts. In some cases, direct observation of an event involving one of the collected species occurred after botanical collection was complete. These post hoc behavioral observations are reported in this paper, although they did not impact sample selection.

Collection of sample material

Plants were collected from the Sonso community home range following best practice procedures [ 65 ], using sustainable harvesting methods [ 66 ]. See S1 File for more information. Voucher accession numbers are reported in Table 3 . Digital images of voucher specimens can be found in S3 Fig . The currently recognized scientific names of each species were confirmed on https://mpns.science.kew.org/ . Plant family assignments were done in accordance with The Angiosperm Phylogeny Group IV guidance [ 67 ].

Ethnobotanical literature review

We conducted a post-hoc ethnomedicinal review of all species collected for this study using Google Scholar, PROTA, and Kokwaro’s ethnomedicinal pharmacopeia [ 68 ]. To search databases, we used scientific names and synonyms for each plant as keywords [ 65 ].

Plant processing and extractions

At Neubrandenburg University of Applied Sciences, samples were ground using a food processor. Extractions were produced using two solvents and a solvent mixture ( n -hexane, ethyl acetate, and methanol/water ( v/v 9/1)), allowing for the selective isolation of components with varying solubilities and polarities. Methanol-water, the solvent with the highest polarity, generally extracts primary plant metabolites (e.g., polar compounds such as proteins, amino acids, and carbohydrates). Nonpolar solvents like n- hexane extract nonpolar compounds like lipids, making n-hexane a preferred solvent for oil or wax extraction. Extractions with each solvent were achieved through double maceration of new material (non-successively). Extraction suspensions were placed on a shaker at 80 rpm at room temperature for minimum 72h, followed by vacuum filtration. Processes were repeated with the leached material. Filtrates were then combined and dried using a vacuum evaporator, labeled, and stored at -20°C until needed for assays.

Sample solution preparation

To create sample solutions, each crude extract was dissolved in DMSO (Carl Roth) at a concentration of 10 mg/mL. To ensure a homogenous solution, samples were mixed with a vortex mixer and, if necessary, treated with sonication at room temperature or up to 55°C for samples with low solubility. Each extract solution was then tested for inhibition of bacterial growth as well as anti-inflammatory COX-2 inhibition activity. Solutions were stored at -20°C when not in use.

Antibacterial susceptibility tests

A. bacterial strains..

For antibacterial assays, eleven multidrug-resistant clinical isolate strains from nine species were used. This process increased the study’s applicability for early-stage drug discovery, specifically relevant to the threat of antimicrobial resistance (AMR). Seven of these strains (from six species) are classified as ESKAPE pathogens, including Enterococcus faecium (DSM 13590), Staphylococcus aureus (DSM 1104; DSM 18827), Klebsiella pneumoniae (DSM 16609), Acinetobacter baumannii (DSM 102929), Pseudomonas aeruginosa (DSM 1117), and Enterobacter cloacae (DSM 30054), meaning they are highly virulent and resistant to antibiotics [ 69 ]. A strain of the foodborne pathogen Escherichia coli (DSM 498) with AMR as well as a non-resistant E . coli strain (DSM 1576) were also included in the study. Although not an ESKAPE pathogen, E . coli is widely known for causing bacterial diarrhea and AMR strains are a major cause of urinary tract infections [ 70 , 71 ]. Strains of Stenotrophomonas maltophilia (DSM 50170) and Salmonella enterica subsp. enterica (DSM 11320) were also tested. More information on specific clinical isolates/strains, their individual resistance profiles, and antibiotics used can be found in the S5 & S6 Tables in S2 File . Clinical and Laboratory Standards Institute (CLSI) guidelines for broth microdilution testing (M100-S23) were followed [ 72 ].

b. Growth inhibition screening and dose-response study.

The broth dilution in vitro methods for bacterial susceptibility assessment have previously been described by Schultz et al. [ 69 ]. The standardized bacterial working cultures were pipetted into sterile 96-well microtiter plates (Greiner Bio-One International, CELLSTAR 655185). Extracts and antibiotic (64–1 μg/mL), vehicle and sterility controls, were then added into respective wells. Initial optical density measurement (600 nm) was performed, accounting for absorbance of extracts. Plates were incubated at 37°C for 18 h, except for A . baumannii which was incubated for 22h in accordance with strain characteristics ( S5 Table in S2 File ) . After incubation, a final optical density reading (600 nm) was conducted. Percent inhibition values were calculated and the IC 50 and MIC values were determined [ 69 , 73 ]. The IC 50 value is defined as the lowest concentration at which an extract showed ≥ 50% inhibition, and the MIC is the lowest concentration at which an extract displayed ≥ 90% inhibition. A total of 51 samples underwent single-dose pre-screening for growth inhibition (in triplicate) at the concentration of 256 μg/mL on eleven pathogens. Samples showing ≥40% growth inhibition were further tested in a dose-response study with two-fold serial dilution at descending concentrations from 256 to 4 μg/mL. The dose-response experiments were done as biological replicates on separate days in triplicate (technical replicates) to validate reproducibility. Positive controls (antibiotics) and negative controls (vehicle control and sterile media control) were always included. Further details on bacteria standardization can be found in S1 File . Information on plate setup for bacterial library screens and dose-response assays can be found in S4 Fig .

COX-2 inhibition assay

Anti-inflammatory assays were assessed using an in vitro COX inhibitor screening assay kit (Cayman Item No: 701080), with modifications previously described in Schultz et al. [ 74 ]. All extracts were first screened in duplicate for inhibition against human recombinant COX-2 at an initial concentration of 50 μg/mL. For extracts exhibiting at least 50% inhibition, the concentration was then lowered to 10 μg/mL, 5 μg/mL, and 2.5 μg/mL. The most active extracts were taken to dose-response experiments for determination of IC 50 values ( Table 5 ). The assay was done in two steps: 1) the COX reaction step in which the prostaglandin H 2 (PG) was produced (which was further reduced to the more stable prostaglandin F 2α by addition of stannous chloride), and 2) an acetyl choline esterase competitive ELISA step to quantify the produced prostaglandin and calculate a potential enzyme inhibition caused by the extracts. The pure compound and selective COX-2 inhibitor DuP-769 was included as a positive control. DMSO was included as the vehicle control for determining 100% enzyme activity. Information on ELISA plate setup for anti-inflammation assays can be found in S5 Fig .

Ethics statements

Behavioral data used in this study were collected with the approval of the Uganda Wildlife Authority (permit #: COD/96/05) and the Uganda National Council for Science and Technology (permit #: NS257ES). Exportation of samples for pharmacological testing were conducted under UNCST permit #: NS104ES. Behavioral data collection adhered to International Primatological Society’s Code of Best Practice for Field Primatology [ 75 ]. No exported samples were listed under CITES. Plant samples were exported in collaboration with Makerere University (permit #: UQIS00005033/93/PC), issued by the Ugandan government, and transported to Neubrandenburg University of Applied Sciences in accordance with the Nagoya Protocol. A CUREC was approved by the University of Oxford (Ref No.: SAME_C1A_22_080). The authors report no conflict of interest.

Behavioral observations

Several unusual feeding events and putative self-medicative behaviors were recorded over 116 total field days. Table 1 reports all species collected for pharmacological testing and provides behavioral justifications for collection. Images from some of these events can be found in S1 Fig .

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https://doi.org/10.1371/journal.pone.0305219.t001

Individuals with injuries were directly observed ingesting K . anthotheca bark and resin, W . elongata young leaves, C . alexandri bark, and C . parasitica ferns. Individuals exhibiting respiratory symptoms were observed ingesting C . alexandri bark and K . anthotheca bark and resin. Individuals with abnormal urinalysis results (e.g., positive for leukocytes, elevated ketones, and presence of blood) were observed feeding on C . patens dead wood, K . anthotheca bark and resin, and M . leucantha pith. Individuals with recent cases of diarrhea were observed consuming A . boonei and C . patens dead wood, K . anthotheca bark and resin, and W . elongata leaves. Parasitological analyses further suggest individuals with varying degrees of endoparasite infections consumed S . myrtina and C . alexanderi bark, A . boonei and C . patens dead wood, K . anthotheca bark and resin, W . elongata leaves, as well as A . polystachyus and M . leucantha pith. On a day when two individuals were observed leaf swallowing, a scientifically established self-medicative behavior, one was observed consuming K . anthotheca bark and resin, while the other was observed stripping A . polystachyus pith prior to the event. Ingestion of F . variifolia , D . dewevrei , and S . guineense bark were never directly observed during the study period. Examples of bark feeding, dead wood eating, and pith-stripping marks are shown in Fig 1 .

[ a ]: Evidence of F. exasperata bark feeding [ b ] Evidence of C. patens dead wood eating [ c ] Evidence M. leucantha pith-stripping and wadging.

https://doi.org/10.1371/journal.pone.0305219.g001

Ethnobotanical review

Based on our analysis of ethnomedicinal literature spanning various African regions from 1976 to 2022, 11 out of the 13 species tested also had documented ethnomedicinal uses ( Table 2 ).

https://doi.org/10.1371/journal.pone.0305219.t002

Production of extracts and sample information

Taxonomic information and extraction details for the 13 plant species studied, including the plant family, local name (when available), plant part used, solvent for extraction, yield of extraction, extract identification numbers (extract IDs), herbarium accession numbers, and collection location are summarized in Table 3 . Overall, the highest extraction yields were obtained with methanol-water (9/1) as a solvent. The yields from methanol-water extractions for C . parasitica , F . exasperata leaves, and S . guineense stem bark were higher than the other extractions from these samples. The plant samples which had higher yield values with n -hexane, such as the leaves of W . elongata and bark extract of A . boonei , likely have a higher content of lipids (i.e., fatty molecules).

https://doi.org/10.1371/journal.pone.0305219.t003

Library screening against multidrug-resistant human and food bacterial pathogens

Initial screening of extracts involved checking for growth inhibition against each bacterium at a concentration of 256 μg/mL. In total, 45 of the 51 plant extracts (88%) showed activity ≥40% inhibition against at least one of the 11 strains and were thus considered active and brought to dose-response experiments to determine their IC 50 value and MIC. Results from the library screening are reported in S1 Table in S2 File . As all tested plant species in the library screen had at least one extract that was active ( in vitro ) against at least one bacterial strain, no entire species was eliminated for further experimentation. However, as no extracts (at any concentration) inhibited the growth of K . pneumoniae , no further tests were conducted on this bacterium. The extract active against the most bacterial strains (n = 11) was the methanol-water extract of S . guineense stem bark (mwE098a, active against eight strains), followed by the methanol-water S . guineense leaves (mwE098b), the ethyl acetate P . patens dead wood, and the n -hexane A . boonei dead wood (hE092b) extracts, which were each active against seven, seven, and six strains, respectively. The only extract that demonstrated significant inhibition against P . aeruginosa at the highest test concentration was the methanol-water extract from S . guineense bark (mwE098a). This was also the only extract to display significant inhibition at 256 μg/mL against E . cloacae . Of all bacteria in this study, the two strains of E . coli (DSM 498 and DSM 15076) were the most susceptible, with at least one extract from all plant species inhibiting their growth. The E . coli strain with nine known antibiotic resistances (DSM 15076) surprisingly showed growth inhibition in 80% of tested extracts.

Dose-response antibacterial experiments

In dose-response assays, 41 out of the 45 tested extracts (91%) showed activity at ≤256μg/mL, though not all extracts reached MIC values (see Table 4 ). The results, along with standard deviations, are reported in S2 Table in S2 File , while S3 Table in S2 File provides a summary of the number of strains each extract was active against. The strongest in vitro growth inhibition was reported for the methanol-water extract of K . anthotheca bark and resin (mwE088) against Gram-positive E . faecium and the n- hexane extract of A . boonei dead wood (hE092b) against Gram-positive S . aureus (DSM 1104). Both extracts had low IC 50 values of 16 μg/mL (showing strong inhibition), with MIC values of 32 μg/mL against respective strains. E . faecium showed the most general susceptibility to K . anthotheca , with all extracts of this species achieving MIC values (mwE088: 32 μg/mL, eE088: 64 μg/mL, hE088: 128 μg/mL). The ethyl acetate extract of A . boonei dead wood (eE092b) also strongly inhibited the growth of E . faecium (IC 50 : 16 μg/mL; MIC: 64 μg/mL), as did the n- hexane extract of A . boonei dead wood, producing an IC 50 value of 16 μg/mL but failing to reach a MIC value. S . aureus (DSM 1104) was also highly susceptible to the ethyl acetate extracts of A . boonei dead wood (IC 50 : 32 μg/mL; MIC: 128 μg/mL).

https://doi.org/10.1371/journal.pone.0305219.t004

Only one extract, the methanol-water extract of S . guineense bark (mwE098a), was active against the gram-negative P . aeruginosa . This extract exhibited moderate growth inhibition (IC 50 : 64 μg/mL) with no MIC value reached. Despite E . coli (DSM 498) being highly susceptible on the library screen, only two extracts, the methanol-water extract of A . boonei dead wood (mwE092b; IC 50 : 256 μg/mL) and the methanol-water extract of S . guineense leaves (mwE098b; IC 50 : 128 μg/mL), reached IC 50 values at the concentration range tested, with no MICs reached. Interestingly, the strain of E . coli with nine known resistances (DSM 1576) was more susceptible, with 89% (N = 40) of extracts achieving IC 50 values ≤ 256 μg/mL. The most active extract against this strain was the methanol-water extract of K . anthotheca (mwE088; IC 50 : 16 μg/mL; MIC: 256 μg/mL). S . guineense exhibited the highest overall inhibition of S . maltophilia , with all extracts except hE098a displaying IC 50 values of ≤ 256 μg/mL against the bacterium. At the concentration range tested, no extracts yielded MIC values for S . aureus (DSM 18827), A . baumannii , E . cloacae , P . aeruginosa or E . coli (DSM 498).

Anti-inflammatory COX-2 inhibition library screen

Results from the in vitro COX-2 inhibition library screen at descending concentrations are reported in S4 Table in S2 File . At the initial concentration of 50 μg/mL, 43 out of 51 extracts (84%) exhibited an enzyme inhibition of at least 50%, displaying anti-inflammatory activity. This included at least one extract of every plant species. In the next stage of screening, at 10 μg/mL, 18 samples were eliminated. During the final step, at 5 μg/mL, five more were eliminated. The remaining 17 extracts from 10 plant species which displayed inhibition ≥50% at 5 μg/mL, were then introduced to dose-response experiments. The ethyl acetate S . myrtina bark extract (eE089b) was taken to the COX-2 dose-response despite not showing inhibition past 50 μg/mL, as it almost reached the selection limit during analysis and had a relatively high standard deviation. No extracts from W . elongata , C . patens or D . dewevrei showed COX-2 inhibition at 5 μg/mL and thus were excluded from further testing.

COX-2 inhibition dose-response experiments

The most active COX-2 inhibitors were extracts from K . anthotheca (mwE088; hE088; eE088), C . parasitica (mwE087; hE087), F . exasperata (hE093a; eE093a), S . myrtina (hE089a; eE089b), F . variifolia (eE097; hE097), A . polystachyus (hE099; eE099), M . leucantha (hE094), S . guineense (hE098a), A . boonei (hE092b), and C . alexandri (hE096). Results are reported in Table 5 . The strongest COX-2 inhibitor was the K . anthotheca methanol-water bark and resin extract (mwE088) (IC 50 of 0.55 μg/mL), followed by the C . parasitica methanol-water fern extract (mwE087) (IC 50 of 0.81 μg/mL). In contrast, all extracts of the species W . elongata , C . patens , and D . dewevrei failed to show ≥50% inhibition, mostly at the second screening concentration (10 μg/mL). W . elongata extracts notably showed low activity in both antibacterial and COX-2 inhibition assays.

https://doi.org/10.1371/journal.pone.0305219.t005

Plant species with strong pharmacological activity

This study provides the first pharmacological and behavioral evidence of its kind, based on in situ sampling, for the medicinal benefits of bark feeding, dead wood eating, and non-bitter pith stripping behaviors in Budongo chimpanzees. In the following sub-sections, we describe and discuss specific results from five of the tested plant species in further detail. For scope, we selected the two species with the strongest antibacterial properties ( K . anthotheca and A . boonei ) to profile, both of which were the only species to reach 40% inhibition at 16 μg/mL. We also selected C . parasitica to discuss as this species, along with K . anthotheca , exhibited the strongest anti-inflammatory properties. We then discuss results from our S . guineense samples, as this species was effective against the most bacterial strains in our antibacterial assays. Lastly, we selected S . myrtina , as we have behavioral evidence and health data that anecdotally support the use of this species for therapeutic self-medication by Budongo chimpanzees.

Alstonia boonei . Numerous in vitro and in vivo studies, reviewed by Adotey [ 76 ], have reported pharmacological activity in A . boonei bark. However, none of these studies investigated dead wood samples of A . boonei . Consistent with these findings, we found high levels of antibacterial and anti-inflammatory activity in the extracts of this species. Interestingly, extracts from A . boonei dead wood generally exhibited higher activity than living bark. This difference could be due either to a change in active ingredient composition, or possible fungal growth following the tree’s death. While the A . boonei dead wood n -hexane extract (hE092b) exhibited strong growth inhibition against S . aureus (DSM 1104; DSM 18827) and E . faecium at low concentrations in the dose-response assays, the n -hexane bark extract (hE092a) showed no activity <256 μg/mL. Similarly, the ethyl acetate extract of dead wood (eE092b) also strongly inhibited S . aureus (DSM 1104) (IC 50 : 16 μg/mL; MIC: 128 μg/mL) and E . faecium (IC 50 : 16 μg/mL; MIC: 64 μg/mL), while the ethyl acetate bark extract of this species did not even exhibit enough inhibition in the antibacterial library screen to be taken to dose-response assays. However, the methanol-water extract of A . boonei bark (mwE092a) did show activity against E . coli (DSM 498) (IC 50 : 128 μg/mL), as did the methanol-water dead wood extract (mwE092a) (IC 50 : 128 μg/mL), with no MIC values reached in either case. Overall, extracts from A . boonei displayed more potent activity in Gram-positive bacteria, although this effect is more apparent in dead wood than stem bark. In the COX-2 inhibition assays, the n -hexane extract of A . boonei dead wood also showed strong anti-inflammatory inhibition, while the n -hexane extract of the bark only exhibited weak inhibition (at the highest test concentration of 50 μg/mL).

A . boonei is a known medicinal plant across East Africa, commonly used for a variety of reproductive, bacterial, and gastro-intestinal issues, as well as for snake bites, asthma, and dizziness [ 68 , 76 , 77 ]. The bark and latex are intensely bitter, a reliable signal of the presence of bioactive secondary compounds and toxicity [ 94 – 96 ]. Budongo chimpanzees in both communities have been reported to consume both bark and dead wood of A . boonei , often travelling long distances to access these trees and only consuming small amounts of bark per feeding bout [ 45 ]. In an observation reported in this study (see Table 1 : A . boonei , Case 1 ), three males ingested A . boonei dead wood while outside the community’s core area for 1-minute. Two days before the event, one of the individuals had been observed with diarrhea, while also shedding visible tapeworm proglottids ( Bertiella sp.). This sample also contained unidentified protozoa, and Taenia sp. eggs. Pebsworth et al. [ 34 ] also reported an event in which four adult males, all with diverse parasite loads, traveled to a large A . boonei tree and ingested bark.

In the long-term site data, A . boonei bark ingestion was only documented 17 times between 2008–2021 [ 45 ], although this behavior was not systematically reported. In addition, the direct observation of only one A . boonei dead wood eating event, and no A . boonei bark ingesting events over the two four-month periods of observation in this study, suggest that consumption of this species is relatively rare across both communities. While specific pathogenic catalysts for selection of this species remain unknown, based on pharmacological, ethnobotanical, and behavioral data, we propose that A . boonei may be a therapeutic self-medicative resource for Budongo chimpanzees. The relatively strong inhibitory activity of this species against S . aureus , a bacteria associated with causing contamination on the skin leading to chronic wounds [ 97 ], as well as its anti-inflammatory properties, suggests that A . boonei ingestion may have beneficial effects in wound care contexts.

Khaya anthotheca . Previous studies have demonstrated that K . anthotheca bark contains biologically active compounds like gedunins, mexicanolide, phragmalin, and andirobins [ 98 ]. One limonoid identified in the species, anthothecol, has anti-cancer properties [ 99 ]. A study by Obbo et al. [ 100 ] on K . anthotheca bark collected in the Budongo Forest, found strong antiprotozoal activity against Plasmodium falciparum (IC 50 0.96 μg/mL) and Trypanosoma brucei rhodesiense (IC 50 5.72 μg/mL). A related species, K . senegalensis , has been shown to cause cell lysis in some gram-negative bacteria, including Salmonella Typhimurium , Escherichia coli , Shigella sp. and Salmonella sp., by targeting cytoplasmic membranes [ 101 ].

In our antibacterial library screen, of all extracts tested, only the methanol-water extract inhibited growth of A . baumannii (although no IC 50 values were reached in dose-response). The methanol-water extract also inhibited the growth of E . coli (DSM 498) in the library screen, as did the ethyl acetate (eE088) extract, though again no IC 50 values were reached. In our antibacterial dose-response assays, all extracts of K . anthotheca stem bark and resin exhibited strong inhibition against the Gram-positive E . faecium . The most active extract against this strain, which was also the strongest antibacterial result reported in this study, was methanol-water (mwE088) (IC 50 : 16 μg/mL; MIC: 32 μg/mL). All extracts of this species were also found to inhibit E . coli (DSM 1576) in the dose-response experiments, with the methanol-water extract once again also showing the strongest inhibition (IC 50 : 16 μg/mL; MIC: 256 μg/mL). This extract also inhibited the growth of S . maltophilia (IC 50 : 64 μg/mL) in the library screen. Only weak inhibition was found against the food pathogen S . enterica ( n -hexane extract, IC 50 : 256 μg/mL).

K . anthotheca exhibited potent anti-inflammatory activity. Of all extracts tested, the methanol-water K . anthotheca extract (mwE088) displayed the strongest COX-2 inhibition activity (IC 50 : 0.55 μg/mL). Past phytochemical studies on methanol and ethanol-water stem bark extracts from the related species, K . senegalensis , revealed many phenolic compounds, including flavonoids and tannins e.g., [ 101 , 102 ]. Flavonoids act on the inflammatory response, and may block molecules like COXs, cytokines, nuclear factor-кB and matrix metalloproteinases [ 103 ]. Some tannins have also been proven to have strong free radical-scavenging and antioxidant activities [ 104 ]. These compounds are antagonists of particular hormone receptors or inhibitors of particular enzymes such as COX enzymes [ 103 ]. If Khaya species are phytochemically similar, this could help explain K . anthotheca ’s strong COX-2 inhibitory activity.

Across Africa, K . anthotheca is traditionally used for ailments including allergies, fever, headaches, jaundice, bacterial infections, and as a disinfectant for bleeding wounds [ 105 – 107 ]. Our behavioral observations suggest that this species is also a common resource for Sonso chimpanzees, with a total of 65 feeding events recorded throughout the first field season. Of these events, several involved individuals with imbalanced health states (see Table 1 : K . anthotheca ) . On at least three independent occasions, K . anthotheca bark and resin were consumed by wounded individuals. Two adult females on different days tested positive for leukocytes on urinalysis tests within hours of ingesting K . anthotheca , suggesting the presence of infection. One of these individuals was also experiencing severe diarrhea the day prior, the other was found to have trace levels of blood in her urine. A juvenile female with a persistent cough was also observed consuming K . anthotheca bark. On several occasions individuals with high parasite loads or diverse species infection were observed targeting this resource while shedding tapeworm proglottids ( Bertiella sp.). An elderly female was also observed eating bark and resin a few hours prior to leaf-swallowing, a well-established self-medicative behavior known to rid the gut of endoparasites [ 9 , 23 ]. The frequency of K . anthotheca ingestion in the Sonso diet during this period, suggests that individuals have consistent exposure to the antibacterial and anti-inflammatory compounds present in this species. Whether this is a case of passive prevention through intake of a medicinal food, or therapeutic self-medication for a common and wide-spread condition will need further investigation. If used therapeutically, our results suggest this species could be used for treating wounds, bacterial or infections, and/or reducing internal parasite loads.

Christella parasitica.

Extracts of C . parasitica produced notably high anti-inflammatory activity in COX-2 testing, with the methanol-water extract (mwE087) achieving an IC 50 value of 0.81 μg/mL. This same extract, however, exhibited the lowest general activity in the antibacterial library screen. The only antibacterial activity from this species was on E . coli (DSM 498) by the ethyl acetate and n- hexane extracts (eE087; hE087), and on E . coli (DSM 1576) by the n-hexane extract (hE087). The n -hexane extract reached an IC 50 of 128 μg/mL in dose-response assays with no MIC value. Prior to this study, there had been limited pharmacological testing on C . parasitica (though see [ 108 ]), so comparison across studies is not possible.

When we considered the associated behavioral observation involving C . parasitica , we found a notable relevance to our pharmacological results (see Table 1 : C . parasitica , Case 1 ). This observation involved a wounded Sonso adult male (PS) travelling outside of his core area with a large group. It was unclear if this was an inter-community patrol. PS had been observed earlier in the day with a severe hand injury which impacted his mobility, though no open wound was observed. PS separated himself from the group and moved a few meters to a patch of ferns where he began consuming the leaflets. The bout lasted approximately 3-minutes. No other group members were observed feeding on this species, and this was only the second case of fern ingestion reported in Budongo in over 30-years of observations (unpublished site data). Health states of individuals from the past event were unfortunately not recorded. Whether or not C . parasitica ’s highly anti-inflammatory properties were the principal motivator for the selection of this species remains unknown, however, regardless of intention, this plant may have benefitted PS by reducing pain and swelling in his injured hand.

Syzygium guineense.

S . guineense bark and leaves have both previously been found to exhibit a range of pharmacological activity, reviewed by Uddin et al. [ 109 ]. The antioxidant, analgesic, and anti-inflammatory activities of this plant have been attributed to flavonoids, tannins, saponins, carbohydrates, alkaloids, and cardiac glycosides in the extracts [ 109 – 112 ]. In our assays, S . guineense bark exhibited high antibacterial growth inhibition effects in vitro . The methanol-water bark extract (mwE098a) showed some level of inhibition against all bacteria tested in the dose-response assays, except for E . faecium and S . enterica . This was also the only extract, out of all tested, to inhibit growth of P . aeruginosa (IC 50 : 64 μg/mL; MIC: >256 μg/mL) a pathogen known to cause infections in the blood, lungs, and other body parts after surgeries [ 113 ], and was one of two extracts to reach a MIC value against S . maltophilia (IC 50 : 32μg/mL; MIC: 256 μg/mL). The other extract to reach a MIC value was the ethyl acetate S . guineense bark extract (eE098a; IC 50 : 64 μg/mL; MIC: 256 μg/mL). All bark and leaf extracts showed strong inhibition against E . coli (DSM 1576) in the dose-response assays, with the strongest results coming from the methanol-water extracts (mwE098a and mwE098b). All bark and leaf extracts of this species, except for the n -hexane bark extract (hE098a), inhibited E . cloacae , and were the only extracts in the study to do so. E . cloacae , while part of normal intestinal flora, can cause UTI’s and respiratory infections in humans [ 114 ]. S . guineense extracts were also the only extracts to inhibit A . baumannii at a concentration <256 μg/mL, with the methanol-water bark extract showing the strongest inhibition. A . baumannii can cause infections in wounds, blood, urinary tracts, and lungs [ 115 ]. The efficacy of methanolic extracts from this species suggests that the active compounds are polar molecules. In the anti-inflammatory COX-2 inhibition dose-response assays, only the n -hexane bark extract displayed strong inhibitory effects (IC 50 : 2.42 μg/mL), while the other extracts failed to exhibit significant activity during the pre-screening or ≥ 50% inhibition at 10 μg/mL. The COX-2 inhibition assays showed no inflammatory inhibition amongst leaf extracts at tested concentrations.

S . guineense can be found throughout Sub-Saharan Africa and is a common traditional medicine, for malaria [ 116 ]. The bark is also used for stomach aches, diarrhea, internal parasites, and infertility [ 68 , 109 ]. Ingestion of S . guineense bark is rare in Budongo, with no direct observations in either community throughout the study period, and only six total cases between 2008–2021 documented in the site’s long-term data. No observations of leaf ingestion of this species have ever been reported. The infrequent ingestion of S . guineense bark implies a more targeted use, making it unlikely to be a medicinal food. Instead, our pharmacological findings make this resource a strong candidate as a putative, therapeutic self-medicative resource. Unfortunately, as there is currently no health data associated with individuals who have recently consumed S . guineense bark, we do not yet know which properties chimpanzees may be targeting. However, based on pharmacological results, we recommend further investigation into this species as a curative agent for respiratory-related infections.

Scutia myrtina.

Kritheka et al. [ 117 ] in their study on the bioactivity of S . myrtina , found in vivo evidence that this species possesses dose-dependent anti-inflammatory, antimicrobial, and antifungal properties. Across our antibacterial assays, the bark sample of this species collected from the stem inhibited E . faecium (eE089a) and E . coli DSM 1576 (eE089a; mwE089a) in dose-response tests at concentrations ≤256 μg/mL. The refuse sample, collected from the ground below the plant’s stem, inhibited A . baumannii (hE089b), E . faecium (eE089b), and E . coli DSM 1576 (mwE089b; eE089b; hE089b) in dose-response tests below the specified concentration. Interestingly, the refuse sample inhibited more bacteria species overall than the fresh bark. The most potent antibacterial growth inhibition effects came from the ethyl acetate bark sample against E . faecium (eE089a; IC 50 : 64 μg/mL), though no MIC value was reached. In the COX-2 inhibition assays, the n- hexane bark extract had the fifth strongest inhibitory effect in vitro (hE089a; IC 50 : 1.19 μg/mL) out of all samples, while the ethyl acetate refuse bark sample was less potent, though still moderately active (E089b; IC 50 : 7.49 μg/mL).

As far as the authors know, this is the first published report presenting both behavioral and pharmacological evidence for S . myrtina bark as a putative medicinal resource amongst free-ranging chimpanzees (though see [ 118 ] for evidence based on food-combinations). Our behavioral observations indicate that an individual with a diverse and intense parasite infection deliberately sought out the bark of this species. The Budongo chimpanzees may, therefore, utilize S . myrtina as an anthelminthic. Across traditional accounts from multiple regions, S . myrtina is commonly used by people as an anthelminthic to treat intestinal worms [ 68 ], while aerial parts are also used to treat various bacterial infections. As we were not able to conduct urinalysis on the consumer during or after this event, we cannot determine whether the individual also harbored a bacterial infection at the time of ingestion. However, this possibility cannot be ruled out. Based on these findings, we propose S . myrtina be added to the list of putative chimpanzee self-medication behaviors as a treatment for internal parasites, and we encourage further exploration into the other specific chimpanzee health conditions that this species may help ameliorate.

Assessment of putative self-medicative behaviors

We synthesized pharmacological and behavioral evidence to assess therapeutic use of species associated with bark feeding, dead wood eating, and pith stripping behaviors. A summary of the antibacterial and anti-inflammatory results for each species is reported in S3 Table in S2 File . Overall, stem bark and dead wood samples were notable for their activity. Bark samples from every species showed >40% antibacterial inhibition against at least one bacterial strain. This activity was also true of the dead wood samples. When plant parts of the same species were tested ( S . guineense and F . exasperata ), barks generally exhibited more potent antibacterial and COX-2 inhibition activity than the leaves, likely to do with the higher concentration of plant secondary metabolites in bark. Our findings offer strong support that bark and dead wood eating of certain species could constitute novel self-medicative behaviors in wild chimpanzees. We also encourage more investigation into the bioactivity of non-bitter pith stripping, as the pith of A . polystachius showed strong antibacterial activity against E . faecium (hE099; IC 50 : 32 μg/mL; MIC: 128 μg/mL), and the piths of both A . polystachius and M . leucantha demonstrated significant anti-inflammatory properties at low concentrations. Future primatological research should prioritize the establishment of multi-disciplinary long-term projects that look systematically at health states of individuals who engage in bark, dead wood, and pith ingestion behaviors. We also encourage further pharmacological testing on other species used for these behaviors in Budongo and across primate field sites.

Drug discovery

Multidisciplinary studies on this topic have potential to lead to the discovery of new medicines which may benefit our own species [ 119 – 122 ]. Historically, PSMs have played a major role in the development of modern human medicine, and even today, a large portion of medicines are derived either directly or indirectly from plants and other natural materials [ 123 – 127 ]. Antimicrobial resistance is rising to dangerously high levels according to the World Health Organization [ 128 ] requiring the rapid creation of new antibacterial treatments. Infections caused by multi-drug resistant bacteria kill hundreds of thousands of people annually. Our findings of strong antibacterial growth inhibition across numerous plant species growing in Budongo have promising implications for our ability to discover novel compounds in existing forest habitats. Extracts should also be tested against additional bacteria and for anti-virulence effects, e.g., inhibition and disruption of biofilm formation, quorum sensing and toxin production, pursuing development of new therapeutic strategies that apply less evolutionary pressure, likely resulting in emergence of less antibiotic resistances in the future. Phytochemical characterization using advanced techniques, such as LC-ToF-MS and NMR, as well as potentially AI-assisted untargeted metabolomics approaches, are now needed to identify substances present in the most active extracts. This may eventually lead to the isolation and structure elucidation of yet unknown active ingredients and make way for determining their pharmacological selectivity and toxicity, while also taking potential synergistic effects into account.

Simultaneously, we are currently faced with a pressing need for more effective treatments to combat symptoms of acute inflammation and mediate long-term consequences of chronic inflammatory diseases [ 129 ]. The prostaglandin-producing cyclooxygenase-2 (COX-2) mediates and regulates pain, fever, wound inflammation, and many other medical disorders, as it plays a crucial role in the host organism’s defense against pathogens and injury. COX-2 inhibition has the same mechanism of action as non-steroidal anti-inflammatory drugs (NSAIDs). While inflammation is a normal part of the body’s defense against injury or infection, it can be damaging when occurring in healthy tissues or over a protracted period. Chronic inflammation can lead to cardiovascular diseases (CVD) and cancer, the two leading global causes of death [ 130 ]. Past studies have shown that the IC 50 values of Aspirin and ibuprofen (pure compounds and common NSAIDs) are 210 μg/mL and 46 μg/mL respectively for COX-2, and 5 μg/mL and 1 μg/mL respectively for COX-1 [ 131 , 132 ]. The in vitro COX-2/COX-1 selectivity ratio for Aspirin and ibuprofen is 42 and 46 respectively. Surprisingly, the 17 most active extracts in our COX-2 assays display lower IC 50 values than these popular NSAIDs, meaning our extracts have more potent inhibitory effects on the inhibition of COX-2 than the most common anti-fever and anti-pain drugs on the market. While COX-1 assays were beyond the scope of this study, future research should investigate COX-1 inhibition activity of these 17 extracts to calculate COX-2/COX-1 selectivity ratios. Doing so will allow for preliminary assessment of potential side effects, selectivity, and efficacy before future in vivo experiments can commence.

Future directions

Future research on this topic would benefit from the inclusion of control samples (plants or plant parts not consumed by chimpanzees); however, in this study, assay costs were a prohibiting factor. Additional information regarding the nutritional and mineral content of the species mentioned in this study is needed to better understand the motivations for ingestion. However, bioactivity and nutritional/mineral content are by no means mutually exclusive. It is, therefore, highly likely that these resources provide multiple benefits to consumers.

Future studies should also consider ecological variables. For example, different individual plants of the same species should be tested across habitat types to determine whether bioactivity varies based on location, age, life history, or time of harvest. Situating samples in their ecological context will provide a better understanding of whether chimpanzees select resources based on species alone, or other more nuanced criteria. Lastly, climatic studies in combination with pharmacological testing should examine how climate change may impact bioactivity of these plants, as shifting weather patterns have already been shown to alter nutritional content [ 133 ]. This information will be critical for establishing protected habitats that can sustain healthy, wild, primate populations.

Conclusions

As we learn more about the pharmacological properties of plants ingested by chimpanzees in the wild, we can expand our understanding of their health maintenance strategies. Our results provide pharmacological evidence, from in vitro assays of plant parts consumed by wild chimpanzees collected in situ , for the presence of potent bioactive secondary plant metabolites in Budongo chimpanzee diets for a variety of potential illnesses previously not considered. Whether these resources are consumed intentionally as a form of therapeutic self-medication or passively as medicinal foods, must be assessed on a case-by-case basis, taking behavioral observations into account.

For the field of zoopharmacognosy to progress, we encourage continued multidisciplinary collaboration between primatologists, ethnopharmacologists, parasitologists, ecologists, and botanists [ 9 ]. Beyond improving our broad understanding of chimpanzee health maintenance, multidisciplinary studies will benefit our own species, potentially leading to the discovery of novel human medicines to combat the looming problem of growing drug-resistance. For this to happen, however, it is imperative that we urgently prioritize the preservation of our wild forest pharmacies as well as our primate cousins who inhabit them.

Materials availability

Voucher specimens for each species were deposited at the Makerere University Herbarium in Kampala, Uganda for taxonomic identification and storage. A duplicate set was deposited at the University of Oxford Herbarium for permanent storage.

Supporting information

S1 fig. budongo chimpanzees consuming resources tested in this study..

a.) IN eating K . anthotheca bark and resin b.) MZ eating S . myrtina bark c.) KC stripping A . polystachyus pith d.) MB eating C . patens dead wood e.) OZ eating S . guineense bark (post-study period) g.) MZ eating F . exasperata bark.

https://doi.org/10.1371/journal.pone.0305219.s001

S2 Fig. Generalized multi-method workflow used in this study.

https://doi.org/10.1371/journal.pone.0305219.s002

S3 Fig. Voucher samples collected in duplicate.

a . ) C . alexandri (00243133G) b . ) A . polystachius (00243136J) c . ) W . elongata (00243129L) d . ) C . parasitica (00243122E) e . ) K . anthotheca (00243123F) f . ) F . variifolia (51195) g . ) M . leucantha (51203) h . ) A . boonei (51204) i . ) D . dewevrei (00243132F) j . ) S . guineense (00243135I) k . ) S . myrtina (00243128K) l . ) F . exasperata (00243130D).

https://doi.org/10.1371/journal.pone.0305219.s003

S4 Fig. Plate layouts for growth inhibition assays.

[Top] Library Screen: done in 96-wells-mikrotiterplate; AB: Antibiotic as positive control; DMSO: vehicle control / negative control; GC: growth control: containing working culture, to check whether the bacterium grew/active; [Bottom] Dose-Response: done in descending concentration of samples, DMSO, and antibiotic. MB: Media blank, consisted of CAMHB as negative/ sterile media control; DMSO as negative/ vehicle control; GC: growth control, consisted of working culture.

https://doi.org/10.1371/journal.pone.0305219.s004

S5 Fig. ELISA assay setup for anti-inflammatory assay.

https://doi.org/10.1371/journal.pone.0305219.s005

S1 File. Supplementary materials: Methods .

https://doi.org/10.1371/journal.pone.0305219.s006

S2 File. Supplementary tables.

https://doi.org/10.1371/journal.pone.0305219.s007

Acknowledgments

We are grateful to all the field staff working in Budongo who provided invaluable instruction and guidance, generously sharing both scientific insight and traditional knowledge. This study could not have been done without their contributions. Specifically, we would like to thank members of the Perspectives Collective: Chandia Bosco, Monday Mbotella Gideon, Adue Sam, Asua Jackson, Steven Mugisha, Atayo Gideon, and Kizza Vincent, and Walter Akankwasa, as well as site director David Eryenyu. We would also like to thank Godwin Anywar for his assistance with plant identification at the Makerere Herbarium, Stephen Harris at the University of Oxford’s Herbarium for his facilitation of voucher storage, and the Natural History Museum in London for their aid in parasite identification. We are grateful to Vernon Reynolds who founded the field site and to the Royal Zoological Society of Scotland for providing core support. We also gratefully acknowledge the Uganda Wildlife Authority and the Uganda National Council for Science and Technology for granting permission to conduct research in Uganda. Lastly, thank you to the staff and students at Neubrandenburg University of Applied Sciences who made this collaboration possible, and to research assistant, Finn Freymann, for his help with botanical extractions.

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Research on the renewal of multi-story high-density urban landscape based on property rights land—a case study of the self-built liu houses in zherong, fujian province, 1. introduction, 2. materials and methods, 3. results: case study—zherong county, fujian province.

② History of the County
(ii) Regional Morphological Feature: Lack of Certain Regularity
(iii) Architectural Feature: Significant Diversity Exists
(iv) Summary of Early Liu House Features
② Sample B: Mid-term Liu Houses (i) Morphology and Structure of Land Parcels
(ii) Regional Morphological Feature: Pattern with Certain Regularity
(iii) Architectural Feature: Balanced Similarity and Diversity
(iv) Summary of Mid-Term Liu House Features
③ Sample C: Late Liu Houses (i) Morphology and Structure of Land Parcels
(ii) Regional Morphological Feature: Strong Regularity
(iii) Architectural Features: Highly Unified Similarity
(iv) Summary of Late Liu House Features
② Estimation-Based Renovation Framework of Liu House Areas in Zherong

4. Discussion

(ii) Individual Construction Driven by the Residents
② Mid-term Liu Houses: Morphological and Architectural Features Affected by both the Government and the Residents (i) Land Parcels Shaped by Administrative Planning
(ii) Collective Construction Driven by Spontaneously Formed Resident Groups
③ Late Liu Houses: Unified Morphological and Architectural Features Under Developers’ Direct Control (i) Commercial Real Estate Development
(ii) Unified Construction Led by Commercial Developers

5. Conclusions

Author contributions, data availability statement, conflicts of interest.

Zherong County Local Chronicles Compilation Committee. Zherong County Chronicle (1949–1995) ; Zhonghua Book Company: Beijing, China, 1995; pp. 78–79. [ Google Scholar ]
Dong, W.; Gao, X.; Han, W.; Wang, J. Renewal Framework for Self-Built Houses in “Village-to-Community” Areas with a Focus on Safety and Resilience. Buildings 2023 , 13 , 3003. [ Google Scholar ] [ CrossRef ]
Jiao, L.; Wu, Y.; Fang, K.; Liu, X. Typo-Morphological Approaches for Maintaining the Sustainability of Local Traditional Culture: A Case Study of the Damazhan and Xiaomazhan Historical Area in Guangzhou. Buildings 2023 , 13 , 2351. [ Google Scholar ] [ CrossRef ]
Conzen, M.R.G. Alnwick, Northumberland: A Study in Town-Plan Analysis ; Institute of British Geographers Publication: London, UK, 1960; Volume 27. [ Google Scholar ]
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Click here to enlarge figure

Content	Sub-Content	Detailed Content	Indicators	Weight Values
Building scale	Heights	Average floor height	The average floor height of the target building is added or subtracted from the average of the block and block in which the building is located, and the difference is recorded as H1 and H2, respectively.	In the calculation, the weight values k1 and k2 are used, respectively.
	Heights	Number of floors	Add or subtract from the average of the blocks and blocks, and the difference is recorded as H1 and H2.	In the calculation, the weight values K1 and K2 are used, respectively.
	Volume	Width	Add or subtract from the average of the blocks and blocks, and the difference is recorded as w1 and w2.	In the calculation, the weight values q1 and q2 are used, respectively.
		Length	Add or subtract from the average of the blocks and blocks, and the difference is recorded as d1 and d2.	In the calculation, the weight values q3 and q4 are used, respectively.
		Area	Add or subtract from the average of the blocks and blocks, and the difference is recorded as a1 and a2.	In the calculation, the weight values q5 and q6 are used, respectively.
	Concave and convex	If courtyard	Bool value is ɑ1.	The weight value x1 is used in the calculation.
		If terrace	Bool value is ɑ2.	The weight value x2 is used in the calculation.
		If Bay window	Bool value is ɑ3.	The weight value x3 is used in the calculation.
		If concave and convex over 50 cm	Bool value is ɑ4.	The weight value x4 is used in the calculation.
Plan elements	Building setback	Building setback scales	Bool value is ɑ5.	The weight value y1 is used in the calculation.
Facade elements	Roof form	If similar	Bool value is ɑ6.	The weight value u1 is used in the calculation.
	Mian form	If similar	Bool value is ɑ7.	The weight value u2 is used in the calculation.
	Base form	If similar	Bool value is ɑ8.	The weight value u3 is used in the calculation.
	Color	If similar	Bool value is ɑ9.	The weight value u4 is used in the calculation.
	Material	If similar	Bool value is ɑ10.	The weight value u5 is used in the calculation
	Ornament	If similar	Bool value is ɑ11.	The weight value u6 is used in the calculation,

Types of Liu Houses	Time	Architectural Features
Early Liu House	1980–1990	(1) The number of floors is no less than 3 and no more than 6 floors. (2) The pediments of the townhouses are independent of each other, and the construction is led by the residents.
Mid-term Liu House	1990–1995	(1) The number of floors is no less than 3 and no more than 6 floors. (3) Townhouse buildings share common pediments.
Late Liu House	1995+	(1) The number of floors is no less than 3 and no more than 6 floors. (2) Townhouse buildings share common walls and foundations and are constructed by the developer in a unified manner.

Content	Sub-Content	Detailed Content	Difficulty of Renovation Construction	Weight Values
Building scale	Heights	Average floor height	High	Considering the difficulty of the update construction, k1 = k2 = 10
	Heights	Number of floors	High	Considering the difficulty of the update construction, K1 = K2 = 10
	Volume	Width	Very high	Considering the difficulty of the update construction, q1 = q2 = 20
		Length		Considering the difficulty of the update construction, q3 = q4 = 20
		Area		Considering the difficulty of the update construction, q5 = q6 = 20
	Concave and convex	If courtyard	High	x1 = 10 is set to take into account the difficulty of updating the construction
		If terrace		x1 = 10 is set to take into account the difficulty of updating the construction
		If Bay window		x1 = 10 is set to take into account the difficulty of updating the construction
		If concave and convex over 50 cm		x1 = 10 is set to take into account the difficulty of updating the construction
Plan elements	Building setback	Building setback scales	Very high	y1 = 20 is set to take into account the difficulty of updating the construction
Facade elements	Roof form	If similar	Medium	u1 = 2 is set to take into account the difficulty of updating the construction
	Mian form	If similar	Medium	u2 = 2 is set to take into account the difficulty of updating the construction
	Base form	If similar	Low	u3 = 1 is set to take into account the difficulty of updating the construction
	Color	If similar	Low	u4 = 1 is set to take into account the difficulty of updating the construction
	Material	If similar	Medium	u5 = 2 is set to take into account the difficulty of updating the construction
	Ornament	If similar	Low	u6 = 1 is set to take into account the difficulty of updating the construction

Control Level	Control Target	Range of Number X	Control Methods
Level 1	The diversity of form is high	>180	not much guidance required
Level 2	Diversity is comparatively high	100–180	Certain guidance required
Level 3	Diversity is normal	50–100	Constraints and control needed
Level 4	Diversity is comparatively low	20–50	Strict constraints and control needed
Level 5	Diversity is very low	<20	An overall renovation may be more suitable

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Li, N.; Cao, Z.; Wang, K. Research on the Renewal of Multi-Story High-Density Urban Landscape Based on Property Rights Land—A Case Study of the Self-Built Liu Houses in Zherong, Fujian Province. Buildings 2024 , 14 , 1998. https://doi.org/10.3390/buildings14071998

Li N, Cao Z, Wang K. Research on the Renewal of Multi-Story High-Density Urban Landscape Based on Property Rights Land—A Case Study of the Self-Built Liu Houses in Zherong, Fujian Province. Buildings . 2024; 14(7):1998. https://doi.org/10.3390/buildings14071998

Li, Ningyuan, Zhenyu Cao, and Ka Wang. 2024. "Research on the Renewal of Multi-Story High-Density Urban Landscape Based on Property Rights Land—A Case Study of the Self-Built Liu Houses in Zherong, Fujian Province" Buildings 14, no. 7: 1998. https://doi.org/10.3390/buildings14071998

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Acta Crystallographica Section D
Acta Crystallographica
Section D STRUCTURAL BIOLOGY

1. Introduction

2. materials and methods, 4. discussion, 5. conclusion and outlook, supporting information.

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research papers \(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

STRUCTURAL
BIOLOGY

Factors affecting macromolecule orientations in thin films formed in cryo-EM

a National Centre for Biological Sciences, Tata Institute of Fundamental Research, GKVK Post, Bellary Road, Bengaluru 560 065, India * Correspondence e-mail: [email protected]

The formation of a vitrified thin film embedded with randomly oriented macromolecules is an essential prerequisite for cryogenic sample electron microscopy. Most commonly, this is achieved using the plunge-freeze method first described nearly 40 years ago. Although this is a robust method, the behaviour of different macromolecules shows great variation upon freezing and often needs to be optimized to obtain an isotropic, high-resolution reconstruction. For a macromolecule in such a film, the probability of encountering the air–water interface in the time between blotting and freezing and adopting preferred orientations is very high. 3D reconstruction using preferentially oriented particles often leads to anisotropic and uninterpretable maps. Currently, there are no general solutions to this prevalent issue, but several approaches largely focusing on sample preparation with the use of additives and novel grid modifications have been attempted. In this study, the effect of physical and chemical factors on the orientations of macromolecules was investigated through an analysis of selected well studied macromolecules, and important parameters that determine the behaviour of proteins on cryo-EM grids were revealed. These insights highlight the nature of the interactions that cause preferred orientations and can be utilized to systematically address orientation bias for any given macromolecule and to provide a framework to design small-molecule additives to enhance sample stability and behaviour.

Keywords: cryo-EM ; thin films ; preferred macromolecular orientation ; surfactants ; temperature .

EMDB references: CRP pentamer with CTAB, EMD-37864 ; CRP decamer with CTAB, EMD-37865 ; PaaZ with CTAB at 4°C, EMD-37866 ; catalase with SLS, EMD-37952 ; spike with CTAB, EMD-37953 ; catalase at 20°C, EMD-37954 ; catalase at 4°C, EMD-37955 ; catalase with CTAB, EMD-37956 ; β-galactosidase, no tag, EMD-39808 ; β-galactosidase, with tag, EMD-39809

PDB references: CRP pentamer with CTAB, 8wv4 ; CRP decamer with CTAB, 8wv5 ; PaaZ with CTAB at 4°C, 8wv6 ; catalase with SLS, 8wzh ; spike with CTAB, 8wzi ; catalase at 20°C, 8wzj ; catalase at 4°C, 8wzk ; catalase with CTAB, 8wzm

Examples of anisotropic cryo-EM maps resulting from orientation bias. The upper panel shows the reference-free 2D class averages of ( ) SARS-CoV-2 spike protein and ( ) human erythrocyte catalase. For the spike protein, preferred bottom views are observed. In the case of catalase, a preference for the top/bottom view is evident. In the lower panel, 3D maps with anisotropic features are shown for the preferred and perpendicular views as labelled. The symmetries applied during reconstruction were 1 and 2 for the spike protein and catalase, respectively.

To achieve this goal, we tested some commonly used surfactants with different properties on a set of five proteins: C-reactive protein (CRP) pentamers, CRP decamers, catalase, PaaZ and spike. In addition, we explored the effect of the presence of the histidine tag for spike and β -galactosidase and of physical factors such as the temperature during the sample-application step for catalase and PaaZ. We also serendipitously observed an effect of the grid hole dimensions of the holey carbon grid on the orientation distribution of catalase and discuss this briefly. Through this analysis, we identified factors that affect and determine the behaviour of the macromolecule on grids before freezing and studied their effects with a focus on the preferred orientation problem. This account highlights the factors that contribute to orientation bias and provides valuable information that can assist in achieving the optimal freezing conditions for any given macromolecule.

2.1. Source of proteins

Human C-reactive protein (catalogue No. C4063) and human erythrocyte catalase (catalogue No. C3556) were obtained from Sigma–Aldrich. The protein samples were either concentrated using an Amicon 100 kDa concentrator or diluted in respective buffers for grid freezing. All detergent stocks were made in ultrapure water and dilutions were made and used on the day of the experiment.

The SARS-CoV-2 S plasmid was a kind gift from the Krammer laboratory at Icahn School of Medicine, Mount Sinai. The spike gene was amplified from the plasmid and subcloned in the BacMam vector with a C-terminal HRV 3C cleavage tag followed by a seven-histidine and twin Strep tag. Bacmid DNA and virus were prepared as described in the Invitrogen Bac-to-Bac manual. After two generations of amplification in Sf9 cells, the V2 virus was used for transfection of HEK293F cells at a density of 2 million per millilitre. Sodium butyrate (4 m M ) was added to enhance the production of protein 8 h post-infection. The medium supernatant containing the secreted spike protein was harvested on day 3 by centrifuging the cells at 150 g for 10 min. The medium was incubated with pre-equilibrated Ni–NTA (Qiagen) beads at room temperature for 1–2 h (1 ml of beads per 200 ml of medium). The Ni–NTA beads were washed with phosphate-buffered saline (PBS) containing 20 m M imidazole, followed by elution with 280 m M imidazole in PBS. The eluted protein was run on SDS–PAGE to assess its purity, further concentrated and injected onto a 24 ml Superdex 200 (Cytiva) size-exclusion column to exchange the buffer to 50 m M Tris pH 8, 200 m M NaCl, 1 m M DTT. To cleave the tag, the eluted fractions from Ni–NTA chromatography were diluted with 50 m M Tris pH 8, 200 m M NaCl, 1 m M DTT and incubated with HRV 3C protease overnight at 4°C, followed by reverse IMAC to obtain the spike protein without tag in the flowthrough. The flowthrough was concentrated using an Amicon 100 kDa concentrator, flash-frozen using liquid nitrogen and stored at −80°C until further use.

2.2. Grid preparation

6.3 µl of the protein was thawed on ice and 0.7 µl of 10× additive (surfactant) stock was added to obtain a final concentration of 1×. This sample was incubated on ice for 2–5 min and then centrifuged at 21 000 g for 20 min. Meanwhile, a Vitrobot Mark IV (Thermo Fisher Scientific) chamber was equilibrated at 20°C (unless stated otherwise) and 100% humidity. Quantifoil 1.2/1.3 or Quantifoil 0.6/1 grids were glow-discharged in a reduced-air environment with a PELCO easiGlow chamber using a standard setting of 25 mA current for 1 min. The grid was mounted on the Vitrobot Mark IV and 3 µl of sample was applied to the grid. A blotting time of 3–4 s, a wait time of 10 s and a blot force of 0 were used to obtain a thin film of the specimen. For data sets where grids were prepared at different temperatures, the protein was incubated on a thermal block at the required temperature for 3–7 min before applying it to the grid. The Vitrobot chamber was maintained at the required temperature and 100% humidity. The blot time, blot force and wait time were kept constant.

2.3. Grid screening and data collection

Summary of the parameters for data sets collected under different conditions

Protein	Condition	Grid type (Quantifoil)	Buffer composition	Protein concentration (mg ml )	Detector	Box size (pixels)	Pixel size
CRP pentamer and decamer	No additive	1.2/1.3	20 m Tris pH 8, 280 m NaCl, 5 m CaCl , 0.03% NaN	2.1	Falcon 3	256	1.07
	CTAB	1.2/1.3		2.6	Falcon 3	256	1.07
	SLS	1.2/1.3		2.6	K2	320	1.08
	Tween 20	1.2/1.3		3.6	K2	320	1.08
	Tween 80	1.2/1.3		6.8	K2	320	1.08
	A8-35	1.2/1.3		3.6	Falcon 3	320	1.07
Catalase	No additive, 20°C	1.2/1.3	50 m Tris pH 8	0.625	Falcon 3	256	1.07
	CTAB	1.2/1.3		3.4	K2	320	1.08
	SLS	1.2/1.3		3.4	Falcon 3	256	1.07
	Tween 20	1.2/1.3		3.4	K2	320	1.08
	Tween 80	1.2/1.3		4.1	Falcon 3	320	1.07
	A8-35	1.2/1.3		3.4	Falcon 3	320	1.07
	4°C	1.2/1.3		0.625	Falcon 3	256	1.07
	37°C	1.2/1.3		0.625	Falcon 3	320	1.38
	4°C	0.6/1		0.625	Falcon 3	320	1.07
	20°C	0.6/1		0.625	Falcon 3	256	1.07
PaaZ	No additive, 4°C	0.6/1	25 m HEPES pH 7.4, 50 m NaCl	0.8	Falcon 3	320	1.07
	No additive, 20°C	0.6/1		0.8	Falcon 3	256	1.07
	No additive, 37°C	0.6/1		0.8	Falcon 3	—	1.38
	CTAB, 4°C	0.6/1		0.8	Falcon 3	256	1.07
Spike	With tag, no additive	0.6/1	50 m Tris pH 8, 200 m NaCl, 1 m DTT	1	Falcon 3	256	1.07
	With tag, with CTAB	0.6/1		1.3	Falcon 3	320	1.07
	Without tag, no additive	0.6/1		2	Falcon 3	256	1.07
	Without tag, with CTAB	0.6/1		2	Falcon 3	256	1.07
β-Galactosidase	With tag, no additive	0.6/1	100 m Tris pH 8, 200 m NaCl, 5 m CaCl 2.5 m MgCl , 2 m β-ME	5	Falcon 3	320	1.07
β-Galactosidase	Without tag, no additive	0.6/1	100 m Tris pH 8, 200 m NaCl, 5 m CaCl 2.5 m MgCl , 2 m β-ME	5	Falcon 3	320	1.07

2.4. Data processing and model refinement

3.1. analysis of preferred views of selected macromolecules.

Representative micrographs, with a few selected particles indicated with red circles, and 2D class averages of the test proteins used in this study. ( ) The C-reactive protein (CRP) pentamer adopts a preferred bottom view, which shows the pentameric arrangement of the monomers. ( ) The CRP decamer adopts a preferred side view, which shows the staggered arrangement of two CRP pentamers stacked on top of each other. The same micrograph is used in ( ) and ( ). ( ) Catalase adopts a preferred top view, as seen in the micrograph and 2D class averages. ( ) SARS-CoV-2 spike adopts a preferred bottom view showing the trimeric arrangement. ( ) PaaZ adopts a preferred side view, as seen in the 2D class averages, and the micrograph shows occasional clumping of hexamers on the grids. ( ) β-Galactosidase with an N-terminal polyhistidine tag adopts a preferred side view, as seen in the 2D class averages, and the micrograph shows aggregation on grids. For the above data sets, the catalase and PaaZ grids were prepared at 4°C and all other grids were prepared at 20°C.

3.2. Surfactants affect macromolecule orientation distributions in a charge-dependent manner

Properties of the surfactants used in this study

Additive	Charge	Ionic or non-ionic	CMC	Concentration used	Aggregation number	Molecular weight (Da)	Alkyl-chain length	Saturation in alkyl chain
CTAB	Positive	Ionic	1 m (0.04%)	0.054 m (0.002%)	170	364	16	Saturated
SLS	Negative	Ionic	14.6 m (0.42%)	1.37 m (0.04%)	—	293	12	Saturated
Tween 20	Neutral	Non-ionic	0.06 m (0.007%)	0.04 m (0.005%)	80	1228	12	Saturated
Tween 80	Neutral	Non-ionic	0.012 m (0.002%)	0.038 m (0.005%)	58	1310	18	Unsaturated
A8-35	Negative	Ionic	NA	0.01%	NA	∼9000	NA	NA

Comparison of parameters for no-additive and surfactant-additive data sets

Protein	Condition	No. of particles	Resolution (Å) (half-map FSC 0.143)	Efficiency of Fourier space coverage	Sphericity
CRP pentamer	No additive	14601	18	0.78	NA
	CTAB	36353	3.3	0.80	0.98
	SLS	31699	4.2	0.80	0.97
	Tween 20	25674	3.3	0.80	0.86
	Tween 80	32330	7.5	0.69	NA
	A8-35	26737	10	0.78	NA
CRP decamer	No additive	9419	20	0.52	NA
	CTAB	25992	3.5	0.85	0.98
	SLS	59211	3.7	0.79	0.97
	Tween 20	51784	4.0	0.78	0.92
	Tween 80	36870	4.2	0.79	0.76
	A8-35	104369	3.5	0.78	0.98
Catalase	No additive	138000	2.7	0.72	0.96
	CTAB	153336	2.8	0.76	0.97
	SLS	33241	3.7	0.80	0.98
	Tween 20	88395	2.9	0.78	0.98
	Tween 80	92163	2.9	0.80	0.96
	A8-35	122000	3.1	0.77	0.98
PaaZ	No additive	51393	4.0	0.76	0.80
PaaZ	CTAB	89454	2.3	0.75	0.98

Orientation-distribution plots from (Scheres, 2012 ) of proteins upon the addition of surfactants with varying properties to the sample buffer before grid preparation. The reference structures of the respective proteins are generated by creating a surface representation in from models from PDB entries , , and . ( ) Changes in the CRP pentamer orientation distribution upon the addition of surfactants. The distributions are distinct from each other, except for Tween 20 and Tween 80, which have similar distributions. ( ) Changes in the CRP decamer orientation distribution upon addition; all surfactants lead to a similar even orientation distribution. ( ) Changes in the catalase orientation distribution upon the addition of surfactants, where the charged surfactants have distinct distributions (CTAB and SLS) and the neutral surfactants (Tween 20 and Tween 80) and A8-35 show similar distributions. ( ) Changes in PaaZ orientation distributions upon the addition of the cationic CTAB. The effects of SLS and Tween 20 on PaaZ were also tested, but visual inspection of the micrographs ( ) showed no improvement and no data were collected; therefore they are not included (marked by asterisks). The effects of Tween 80 and A8-35 on PaaZ were not tested.

3.3. The presence of a solvent-exposed polyhistidine tag affects protein orientations in thin films

The effect of a polyhistidine affinity tag on the SARS-CoV-2 spike protein and β-galactosidase orientation distributions. The different parameters that are used to analyse the quality of the maps are shown next to the orientation plots. indicates the number of particles used for reconstruction, indicates the final resolution of the map, indicates the sphericity and indicates the efficiency of Fourier space coverage. ( ) The locations of the tags on the protein models are indicated by black stars. The models used as references are PDB entries and for the spike protein and β-galactosidase, respectively. ( ) The orientation-distribution plots of the spike protein change upon removal of the affinity tag, but the change is not sufficient to obtain an isotropic map. The addition of the cationic CTAB further alters the orientations of the spike protein without tag and leads to a more isotropic map. β-Galactosidase enzyme (bottom panel) orientations change upon removal of the affinity tag and lead to an isotropic high-resolution map without any additive. The unsharpened final combined maps are shown in grey in ( ).

3.4. The temperature of the incubation chamber during freezing affects protein orientations

The effect of temperature during cryo-EM sample preparation of catalase and PaaZ. Micrographs, maps, orientation-distribution plots and the different parameters that are used to analyse the quality of the maps are shown. indicates the number of particles used for reconstruction, indicates the final resolution of the map, indicates the sphericity and indicates the efficiency of Fourier space coverage. ( ) Catalase orientation distributions change significantly when grids are blotted at different temperatures in the absence of any additive. ( ) PaaZ orientation distributions change slightly when grids are held and blotted at different temperatures in the absence of any additive. In the case of PaaZ, the condition with grids prepared at 4°C with CTAB as an additive is included for comparison as this combination led to a high-resolution isotropic map.

It is evident from these observations that physical factors, such as the grid-preparation temperature, can affect protein behaviour and should be considered as an important screening condition when dealing with orientation bias along with surfactants.

3.5. High-resolution map of E. coli PaaZ in ice

High-resolution cryo-EM map from PaaZ grids prepared at 4°C with CTAB additive. ( ) Comparison of the half-maps and map-versus-model FSCs of the PaaZ data set. ( ) The six coloured individually and in cartoon representation fitted into the cryo-EM map (transparent grey) of PaaZ. ( ) Electrostatic potential surface representation of the domain-swapped PaaZ dimer with waters modelled and shown as cyan spheres. ( ) ResLog plot of PaaZ with the experimental and theoretical numbers of particles required to reach a particular resolution. indicates the number of particles used for reconstruction, is the resolution and indicates the factor, as estimated by post-processing. 3 symmetry was applied for the reconstruction and the ResLog plot indicates the number of particles used, not the number of asymmetric units averaged.

Supplementary Figures and Tables. DOI: https://doi.org/10.1107/S2059798324005229/rr5238sup1.pdf

Acknowledgements

We acknowledge the National Cryo-EM Facility, Bangalore for data collection, which is supported by the Department of Biotechnology (DBT/PR12422/MED/31/287/2014), and the computing facility in the Bangalore Life Science Cluster. We thank Professor Ramaswamy S and all of the laboratory members for critical reading of the manuscript. KRV is part of the EMBO Global Investigator Network. KRV acknowledges the discussion with Drs Pamela Williams and Judith Reeks, Astex, UK on β -galactosidase and the effect of tags. The authors declare no conflicts of interest.

Funding information

KRV acknowledges the support of the Department of Atomic Energy, Government of India under Project Identification No. RTI4006. SY acknowledges the graduate fellowship from TIFR/NCBS.

This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence , which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.

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1.Introduction—mention gaps in previous research¹⁻². 2. Summarizing key findings—let your data speak¹⁻². 3. Interpreting results—compare with other papers¹⁻². 4. Addressing limitations—their potential impact on the results¹⁻². 5. Implications for future research—how to explore further¹⁻².
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How to Write a Discussion Section: Writing Guide

What Is in the Discussion Section of a Research Paper

How to Write a Discussion Section in 5 Steps

Step 1. Start Strong: Discussion Section of a Research Paper

Step 2. Answer the Questions in Your Discussion Section of a Research Paper

Step 3. Relate Your Results in a Discussion Section

Step 4. Describe the Limitations in Your Discussion Section

Step 5. Conclude Your Discussion Section With Recommendations

Discussion Section of a Research Paper Example

How to Write a Discussion Section: Final Thoughts

Discussion Section of a Research Paper: Frequently Asked Questions

2. What's the difference between the discussion and the results?

3. What's the difference between a discussion and a conclusion?

4. What is the purpose of the discussion section?

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6 Steps to Write an Excellent Discussion in Your Manuscript

Discussion frame structure

1.Introduction—mention gaps in previous research¹⁻ ²

2. Summarizing key findings—let your data speak ¹⁻ ²

3. Interpreting results—compare with other papers¹⁻²

4. Addressing limitations—their potential impact on the results¹⁻²

5. Implications for future research—how to explore further¹⁻²

6. Conclusion—summarize content¹⁻²

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How to Write the Discussion Section of a Research Paper

Discussion section: what is it, what it does

What is it?

Why is it necessary?

Adds context for your results

Shows what your results actually mean and real-world implications

What to include in your discussion (in the correct order)

Summary of key findings

Begin with key findings with supporting evidence

State clearly and concisely

Interpretation of results

Analyze and interpret your findings

Unexpected or contradictory results

Context and comparison with previous work

How your work compares or contrasts with previous work

How to divide this section into subsections

Limitations

Why limitations don’t have a negative connotation

How limitations add to a researcher's credibility

Implications and significance

Restate your hypothesis

How was it proven or disproven?

How your results contribute to the literature

Future implications of your research

Sample discussion section

How to make your discussion flow naturally

Ensure your structure and ideas are consistent and clearly communicated

How to Start a Discussion Section in Research? [with Examples]

Examples of how to start writing the Discussion section

1. Start by restating the study objective

2. Start by mentioning the main finding

3. Start by pointing out the strength of the study

Most used words at the start of the Discussion

Further reading

Discussion Section Examples and Writing Tips

1. What is the purpose of the discussion section?

2. How should I structure my discussion section?

3. Discussion Examples

3.1. An example of research summary in discussion

3.2. An example of result interpretation in discussion

3.3. An example of literature comparison in discussion

3.4. An example of research implications in discussion