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Does the introduction explain the objective of the research presented in the preprint?

Partly

The introduction begins with a clear ecological framework, and also provides extensive context on parasite manipulation across multiple systems. They also establish the T.gondii lifecycle, and why the manipulation hypothesis is plausible in rodents. In the final paragraph, it explicitly states the paper's objective: "We assess the hypothesis that T. gondii can change human behavior to favor the parasite by changing human behaviors that regulate the fitness of the parasite's definitive host - cats" The main weaknesses are that the introduction is quite long and wordy. The objective isn't clear until the final paragraph. The discussion around cat domestication is also interesting, but may not be entirely necessary.

Are the methods well-suited for this research?

Somewhat inappropriate

There are some key issues in the methods of this research. First and foremost (while this is acknowledged), the n=2 of infected participants is a significant barrier. It is difficult to conduct any meaningful statistical analysis, and challenging to detect true effects even if they exist. In addition, there is no way to account for individual variation, and no ability to control for confounds (e.g. previous cat ownership. In addition, there are issues in the recruitment design. There is volunteer self-selection bias, given that this study would recruit people interested in animal studies. It is also challenging to determine the temporality of this study (we cannot determine if infection --> Cat affection or cat affection --> cat --> infection susceptibility. In terms of the behavioral measurement limitations, there was only 5 minutes of observation which may not capture typical behavior. Overall, the methods are individually sound but the design is underpowered fundamentally.

Are the conclusions supported by the data?

Somewhat supported

There is some level of directional pattern consistency (two infected individuals showed higher cat engagement - 87% vs 75%). The effect was also cat-specific, and the results were broadly consistent with hypothesis predictions. I do not think it is appropriate to claim that the results "aligns with parasite manipulation hypothesis", as stated in the paper. This is a premature conclusion to make from a very small sample. One (or both) of these infected individuals could be random cat lovers and the consistent patterns do not prove causation. There are several alternate explanations that have not been ruled out: (Infection may be side effect not adaptive, cat affection may cause susceptibility to T. Gondii, 2 individuals may be outliers, not representative) While the authors do acknowledge some of these limitations, they still frame the results as "suggestive evidecne", when it is really more that two cases support the underlying hypothesis.

Are the data presentations, including visualizations, well-suited to represent the data?

Somewhat appropriate and clear

The figures are overall technically clear, but don't necessarily convey the full severity of the sample size issue. For example, Figure 2 (specific behaviors is challenging to interpret because the y-axis scale is very small. There are also no confidence intervals or uncertainty representation, which would help the audience understand the overall variability. There is also missing info about the 2 infected individuals (demographic information, outliers, etc.)

How clearly do the authors discuss, explain, and interpret their findings and potential next steps for the research?

Somewhat clearly

The authors are honest about their limitations. They do call the results "suggestive evidence" and not definitive proof. I think there are still ways they could have gone further. When discussing the oxytocin null finding, they note that "even in absence of measurable salivary changes, dopaminergic signaling could still...". This statement is not supported by any peer-reviewed source, and they should be more critical of this null finding. They also use language like "intriguing", "suggestive", which is challenging given the small n. They also could be clearer about their overall next steps on implementation, and they don't specify what a "larger sample" should look like, and how to recruit that population.

Is the preprint likely to advance academic knowledge?

Moderately likely

This study demonstrates the feasibility of studying parasite behavioral manipulation in humans. It also provides a framework of adressing the parasite manipulation question between cats and humans. It is limited, however, because it doesn't definitively prove a causal linkage between T.gondii and human behavior manipulation. I think this study should be framed as a pilot study that is beginning to study a novel question within the human context and generates preliminary data as well as methods that could feasibly be applied to answer this question.

Would it benefit from language editing?

No

Would you recommend this preprint to others?

Yes, but it needs to be improved

Yes. It is novel, honest about its limitations and clearly presents its methodology. The following improvements could help strengthen the paper: 1) Highlight sample size limitation earlier and clearer in the paper 2) Revise data presentations to make small n clearer, 3) Strengthen discussion of oxytocin null finding (be more critical) and 4) Make the research plan for future research more concrete.

Is it ready for attention from an editor, publisher or broader audience?

Yes, after minor changes

I recommend that the author applies the above revisions and then target a specialist journal with a clear framing as a pilot/feasibility study.

Competing interests

The author declares that they have no competing interests.

Use of Artificial Intelligence (AI)

The author declares that they did not use generative AI to come up with new ideas for their review.