The Amygdala and Politics

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This comprehensive review offers a compelling synthesis of the structural and functional plasticity of the amygdala in the context of social hierarchies and political ideologies. By bridging ethological models with human neuroimaging and molecular pathology, the manuscript provides a highly valuable and timely perspective on the neurobiological underpinnings of complex social behaviors.
Major comments
1.    The manuscript effectively discusses the correlation between amygdala volume and political orientation, yet it would benefit from a deeper critical evaluation of the methodological disparities across the cited neuroimaging studies. Different preprocessing pipelines, segmentation algorithms, and sample demographics heavily influence structural measurements, so addressing how these technical variations might explain contradictory findings in the literature would strengthen the overall argument.
2.    While the transition from animal models of social hierarchy to human political systems is conceptually intriguing, the direct translation of these findings requires a more cautious framing. Rodent and primate social dominance behaviors are largely driven by immediate physical and survival imperatives, whereas human political affiliation involves complex cognitive evaluations and cultural conditioning, meaning the physiological stress pathways highlighted may only partially overlap.
3.    The discussion surrounding the potential differences in amygdala structure between political leaders and followers is an interesting hypothesis, but it remains overly speculative given the lack of direct empirical evidence. It would be more rigorous to present this concept explicitly as a future research direction rather than implying a firmly established neurobiological distinction based on historical anecdotes of power and corruption.
4.    Regarding the discussion on molecular changes and tau accumulation in the amygdala during neurodegeneration, the manuscript currently focuses heavily on chronic stress pathways. It would be highly relevant to expand this molecular perspective by mentioning how alternative splicing events also serve as critical mechanisms driving pathological protein aggregation in neurodegenerative conditions that affect emotional centers. Including this perspective would provide a more comprehensive view of the post transcriptional vulnerabilities that might link social stress, amygdala dysfunction, and disease onset. Consider discussing this aspect and referencing the following relevant paper: https://doi.org/10.1016/j.arr.2026.103133
5.    In the section detailing the cellular and molecular changes within the amygdala, the transition between macro level political preferences and micro level pathologies like tau accumulation feels somewhat abrupt. Providing a clearer mechanistic bridge explaining how chronic stress from social stratification specifically accelerates these neurodegenerative molecular cascades would greatly improve the logical flow of this segment.

Minor comments
The self domestication hypothesis is introduced late in the discussion as a framework for understanding emotional tolerance and amygdala reorganization throughout human evolution. Expanding on this concept earlier in the introduction would provide readers with a much stronger theoretical foundation for why the amygdala is specifically targeted when examining the evolution of modern democratic interactions.

Author Response

1. We agree with the reviewer’s observations. However, as noted also by Reviewer 3, the amygdala has received the greatest amount of research attention, with fewer discrepancies reported in the literature.
2. As indicated, there is a clear distinction between social interactions in autocratic systems—more closely related to social dominance—and those in democratic systems.
3. The discussion regarding potential differences in amygdala structure between political leaders and followers in democratic contexts is now explicitly framed as a future research hypothesis. Additionally, we have incorporated the reference concerning the increased amygdala size observed in alpha‑male monkeys (Nooman et al. 2014). At present, no reliable data exist on possible differences between leaders in autocracies versus democracies.
4. The suggested link between chronic stress, amygdala dysfunction, and tau pathology has been added as recommended.
5. As mentioned above, we now propose that chronic stress resulting from social stratification may accelerate neurodegenerative disorders such as tauopathies.

Minor comment

The self‑domestication hypothesis has been added to the Introduction.

Reviewer 2 Report

Comments and Suggestions for Authors

This manuscript provides an interesting, timely, and highly interdisciplinary narrative review of the role of the amygdala in social-emotional behavior, extending the discussion to political orientation, social hierarchy, aging, neuropsychiatric disorders, and molecular mechanisms. The review is generally well written, broad in scope, and successfully integrates evidence from neuroscience, psychology, and social behavior. The emphasis on amygdala plasticity and the proposal of future cellular and molecular mechanisms (including glial changes and tau-related processes) are notable strengths.

Strengths of the report

-This is a comprehensive synthesis of structural, functional, cellular, and molecular aspects of amygdala biology.

-The review is an effective integration of human and animal studies.

-The discussion of plasticity across the lifespan provides a useful conceptual framework.

-The identification of unresolved questions regarding causality between brain structure and political attitudes is particularly valuable.

Primary Comments and Limitations

(1) Section 2.2 (Political Ideology and Brain Structure)

The authors are invited to emphasize that the evidence connecting conservatism and amygdala volume is correlational, with modest effect sizes. Readers must avoid interpreting these findings as proof of a fixed neural foundation for political ideology.

(2) Sections 2.4–2.5 (Role of the Amygdala in Political Ideology)

Several interpretations linking larger amygdala volume to conservative attitudes, hierarchy acceptance, and social behavior should be critically discussed by providing alternative explanations and potential confounding social and environmental influences.

(3) Section 2.9 (Leaders versus Followers of Political Parties)

The discussion of amygdala function in relation to political leadership, power, and corruption is interesting but largely speculative. The authors should clearly distinguish hypothesis-generating concepts from conclusions supported by direct empirical evidence.

(4) Section 3. Discussion (paragraphs discussing conservatism, liberalism, and amygdala volume)

To enhance the final interpretation, the authors should explicitly acknowledge methodological limitations. This involves addressing variability across political systems, cultural contexts, and imaging techniques while emphasizing the significance of replication studies to validate findings.

Future Research Directions

Section 2.3 (Amygdala Functional and Structural Plasticity)

The authors correctly highlight the need for longitudinal studies. This point could be expanded, as longitudinal designs will be essential to determine whether amygdala differences precede political attitudes or emerge as a consequence of life experiences and social environments.

Sections 2.4 and 2.11–2.12

Future studies should move beyond global amygdala volume and investigate specific amygdala nuclei, cellular populations (particularly glial cells), and molecular mechanisms that may contribute to individual differences in social and political behavior.

Section 2.9

The proposed distinction between political leaders and followers represents an original contribution of the review. However, dedicated empirical studies are needed before conclusions can be drawn regarding neural correlates of leadership, power, and corruption.

Discussion Section

The authors are invited to more explicitly state that future research should integrate neuroimaging with social, cultural, developmental, and socioeconomic variables to provide a more comprehensive understanding of how biological and environmental factors jointly shape political and social behavior.

These points would fit well within a minor revision.

Author Response

We thank the reviewer for the positive and constructive comments aimed at improving the manuscript.

Primary comments and limitations

1. We now explicitly state, as suggested, that the evidence linking conservatism and amygdala structure is correlational.
2. Similarly, we clarify that only a correlation between amygdala volume and hierarchy acceptance is proposed.
3. We have added the reviewer’s point that more targeted empirical studies are required before stronger conclusions can be drawn.
4. A brief comment on methodological limitations has been added at the beginning of the manuscript. Furthermore, as detailed below, these issues are expanded upon in the Future Research Directions section.

Future Research Directions

1. Because this topic was also raised by Reviewer 3, we have integrated both reviewers’ suggestions into the Introduction. Specifically, following Reviewer 2’s comments, we now describe how political attitudes and behaviors may change across the lifespan. As the reviewer indicated, longitudinal studies will be necessary to determine whether amygdala changes precede political preferences or arise as a consequence of social environments and experiences.
2. In the section “Amygdala changes at the molecular level: role of tau in the amygdala”, we propose, as suggested, future analyses focusing on specific amygdala nuclei, cellular populations, and molecular mechanisms that may contribute to individual differences in social and political behavior.
3. As noted earlier, we emphasize that more dedicated empirical studies are required before drawing stronger conclusions.
4. Near the end of the Discussion, we now state that more rigorous future research should integrate neuroimaging, cellular and molecular analyses, and social, cultural, developmental, and socioeconomic variables. We also acknowledge that such interdisciplinary collaboration is challenging but essential.

Reviewer 3 Report

Comments and Suggestions for Authors

This paper examines the reported associations between the amygdala and 'behavioral patterns', especially between particularly political parties. This is a potentially interesting topic, the paper is reasonably well written, and a review of this complicated field is welcome. However, I had some concerns about the scope of the review. 

My greatest concern is the restriction of the paper only to the amygdala. There are many subcortical brain regions associated with strong emotions (as covered in various Panksepp publications, for example). It is clear that the amygdala has had the largest share of research work, but this bias may be because it is relatively easy to study in both wet anatomy and brain imaging. It is is far from clear whether the amygdala is the sole (or even the most important) of a wider network of social-emotional-related subcortical brain structures. Indeed, the paper itself acknowledges this: “The amygdala engages in multidimensional processing through extensive connectivity with brain regions involved in sensory integration, reward, visceral responses, memory, emotional valence, and decision-making”. It would be helpful if the paper acknowledged the narrow focus only on the amygdala, which is legitimate focus so long as it is justified.

However, the authors want to make very strong claims about the amygdala: “We examine the reported associations between amygdala structure and function and behavioral patterns observed among followers within specific social groups, particularly political parties. We further propose that these behavioral differences may be underpinned by cellular (neuronal and glial) and molecular (e.g., neuronal protein like tau protein) changes that contribute to variations in both the structure and functional connectivity of the amygdala”. This sentence suggests that the amygdala is the only basis for these political opinions, rather than the best investigated brain structure in relation to these political opinions. It would be helpful if the paper got this important nuance correct.

More over the paper wants to suggest amygdala differences as the principal cause. Here is an example: “Interestingly, survey data from the United States indicate that a majority of adults with ASD who are registered to vote tend to affiliate with the Democratic Party and identify as politically liberal [75]. While the mechanisms underlying this association remain unclear, it suggests a possible link between social cognition, neural substrates, and political preferences.” Survey data are not an evidence base which supports the idea that “these behavioral differences may be underpinned by cellular and molecular changes”. Again, the paper would be better place if it acknowledged the potential psychosocial factors in relation to this.

In general, this felt to me like a review focused on the amygdala and politics. However, the authors have framed something far broader: with the title: “Linking the Amygdala to Social-Emotional Functions”. The category of social-emotional functions is incredibly broad, and we do ourselves a disservice by suggesting that the amygdala is the sole basis for this. I would prefer to see a title that is as focused as ‘The amygdala and politics’, and the text edited to reflect that focus.

In addition, the authors describe the paper as a “meta-analysis”. However, I don’t see an attempt to systematically review and value of the quality of the full literature. Instead, it feels to me like a review, such that statements are made (i.e. cherry-picked) with reference only to one paper from what is a broad literature. For example: “Moreover, gender-dependent differences in amygdala function have been described, with the left amygdala more frequently activated in women [16]”. A meta-analysis needs to rigorously consider (accepting or rejecting depending on criteria) all the papers on a clearly defined topic.

I also found the headings of the paper unhelpful at times. Section 2.5., for example, simply entitled “Amygdala”, although that could’ve been used in a number of other locations. The most helpful would be to have the content explicitly reviewed: these are all the papers on the politics, our review of the suggest that the following five themes…

I liked the aside on Santiago Ramón y Cajal. However, it’s not really an observation about politics, and I feel it would be more at home very early on in the Introduction, or omitted.

Some sentences seem only to describe truisms. For example “It has been suggested that structural and functional changes in the amygdala, a highly plastic brain region, may influence behavior”. One would be hard-pressed to find any brain region which did not ‘influence behaviour’. I would prefer a reread of the text to ensure that all the sentences are adding value.  

Actually, I found the Discussion section, including the element of limitations, the best written and nuanced element of the paper, which I think met all of my objections discussed above. 

In sum, I think the paper needs to be recast to frame itself around the narrower question for which it has expertise, and to ensure that it makes claims about biology which are justifiable. I would be prepared to look at another version of the paper, but it to my mind it is not currently suitable for publication.

Author Response

We now acknowledge the narrow focus on the amygdala. As the reviewer correctly notes, the amygdala has the strongest body of confirmed research. We have also incorporated relevant publications by Panksepp addressing brain regions—including the amygdala—associated with emotional processing.

Following the reviewer’s suggestion, the Abstract has been rewritten.

We also acknowledge the potential influence of psychosocial factors, as recommended.

The title suggested by the reviewer has been adopted.

The reviewer is absolutely correct. We apologize for previously describing the paper as a meta‑analysis. We thank the reviewer for highlighting this important issue.

The recommended changes to headings and section structure have been implemented.

The reference to Santiago Ramón y Cajal now appears in the Introduction.

The sentence referring to truisms has been modified.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors have presented a compelling and scientifically valuable review detailing the structural and functional roles of the amygdala in shaping social hierarchies and political behaviors. I am highly satisfied with the manuscript and generally support its publication in the journal, provided that a few minor revisions are addressed to further enhance its clarity and depth.

Minor comments

1 The manuscript touches upon the self domestication hypothesis and its implications for evolutionary changes in brain structure, yet it would benefit from a brief elaboration on how specific environmental stressors during early human development might have selectively pressured these adaptations. Expanding this point slightly could bridge the gap between primate social dominance and modern democratic behaviors more seamlessly.

2 The manuscript highlights the relationship between the amygdala, chronic stress, the hypothalamic pituitary adrenal axis, and major depressive disorder. To provide a more comprehensive perspective on how emotional dysregulation and depressive states extend beyond localized brain atrophy to affect systemic physiology, I strongly recommend discussing recent multimodal evidence that identifies brain and body pathways. Specifically, incorporating insights on how structural brain changes and proteomic markers link depression with metabolic dysfunction would enrich your discussion on the physiological consequences of stress and social hierarchies. Please consider citing the following relevant study to support this broader biological context. DOI: https://doi.org/10.1017/S003329172610436X

3 While the discussion on age related changes in the amygdala is informative, the transition between sections detailing normal aging and those discussing pathological conditions like Alzheimer disease feels somewhat abrupt. Reorganizing these paragraphs to clearly delineate healthy structural decline from disease driven neurodegeneration will improve the overall narrative flow.

Author Response

Reviewer 1 – Minor comments

1. Regarding the potential influence of specific environmental stressors during early human development on later behavior, we have included a new paragraph beginning at line 64: Adverse environmental conditions during early life can drive adaptive responses to stress that facilitate survival [14]. Such adaptations may result in behavioral traits favoring immediate rewards over long-term benefits [15]. Early-life environments have also been shown to shape the development of coping strategies and stress-related behaviors [16]. From an evolutionary perspective, brain structural changes that support positive social interactions and reduce stress exposure may have contributed to enhanced well-being and quality of life.
2. In response to the reviewer’s comment, we have added a new paragraph at the end of the section Emotions and Amygdala, which reads as follows: In summary, as illustrated in Figure 2, life stress exerts persistent and widespread effects on the prefrontal cortex–hypothalamus–amygdala circuit, as well as on dopaminergic pathways. These effects are mediated, at least in part, by alterations in the hypothalamic–pituitary–adrenal (HPA) axis and may contribute to the development of psychopathological disorders [73]. Indeed, depressive states have been associated with structural changes in the brain. More recently, the combined analysis of brain structural changes and proteomic biomarkers has provided a more comprehensive view of the biological mechanisms underlying depression and related psychiatric disorders [74].
3. To improve the transition between the discussion of amygdala changes during normal aging and those associated with pathological conditions such as Alzheimer’s disease, we have revised the text to provide a smoother progression and avoid an abrupt transition.

Reviewer 3 Report

Comments and Suggestions for Authors

This paper examines the reported associations between amygdala structure and function and behavioral patterns observed among followers within specific social groups, particularly political parties. This is a potentially interesting topic, the paper is reasonably well written, and a review of this complicated field is welcome. However, I had some concerns about the scope of the review. 

My greatest concern is the restriction of the paper only to the amygdala. There are many subcortical brain regions associated with strong emotions (as covered in various Panksepp publications, for example). It is clear that the amygdala has had the largest share of research work, but this bias may be because it is relatively easy to study in both anatomy and brain imaging. It is is far from clear whether the amygdala is the sole (or even the most important) of a wider network of social-emotional-related subcortical brain structures. Indeed, the paper itself acknowledges this: “The amygdala engages in multidimensional processing through extensive connectivity with brain regions involved in sensory integration, reward, visceral responses, memory, emotional valence, and decision-making”. It would be helpful if the paper acknowledged the narrow focus only on the amygdala, which is legitimate focus so long as it is justified.

However, the authors want to make very strong claims about the amygdala: “We examine the reported associations between amygdala structure and function and behavioral patterns observed among followers within specific social groups, particularly political parties. We further propose that these behavioral differences may be underpinned by cellular (neuronal and glial) and molecular (e.g., neuronal protein like tau protein) changes that contribute to variations in both the structure and functional connectivity of the amygdala”. This sentence suggests that the amygdala is the only basis for these political opinions, rather than the best investigated brain structure in relation to these political opinions. It would be helpful if the paper got this important nuance correct.

Moreover, the paper seeks to suggest amygdala differences as the principal cause. Here is an example: “Interestingly, survey data from the United States indicate that a majority of adults with ASD who are registered to vote tend to affiliate with the Democratic Party and identify as politically liberal [75]. While the mechanisms underlying this association remain unclear, it suggests a possible link between social cognition, neural substrates, and political preferences.” Survey data are not an evidence base which supports the idea that “these behavioral differences may be underpinned by cellular and molecular changes”. Again, the people would be better place if it acknowledged the potential psychosocial factors in relation to this.

In general, this felt to me like a review focused on the amygdala and politics. However, the authors have framed something far broader: with the title: “Linking the Amygdala to Social-Emotional Functions”. The category of social-emotional functions is incredibly broad, and we do ourselves a disservice by suggesting that the amygdala is the sole basis for this. I would prefer to see a title that is as focused as ‘The amygdala and politics’, and the text edited to reflect that focus.

In addition, the authors describe the paper as a “meta-analysis”. However, I don’t see an attempt to systematically review and value of the quality of the full literature. Instead, it feels to me like a review, such that statements are made (i.e. cherry-picked) with reference only to one paper from what is a broad literature. For example: “Moreover, gender-dependent differences in amygdala function have been described, with the left amygdala more frequently activated in women [16]”. A meta-analysis needs to rigorously consider (accepting or rejecting depending on criteria) all the papers on a clearly defined topic.

I also found the headings of the paper unhelpful at times. Section 2.5., for example, simply entitled “Amygdala”, although that could’ve been used in a number of other locations. The most helpful would be to have the content explicitly reviewed: these are all the papers on the politics, our review of the suggest that the following five themes…

I liked the aside on Santiago Ramón y Cajal. However, it’s not really an observation about politics, and I feel it would be more at home very early on in the Introduction, or omitted.

Some sentences seem only to describe truisms. For example “It has been suggested that structural and functional changes in the amygdala, a highly plastic brain region, may influence behavior”. One would be hard-pressed to find any brain region which did not ‘influence behaviour’. I would prefer a reread of the text to ensure that all the sentences are adding value.  

In sum, I think the paper needs to be recast to frame itself around the narrower question for which it has expertise, and to ensure that it makes claims about biology, which are justifiable. I would be prepared to look at another version of the paper but it to my mind it is not suitable for publication.

Author Response

Reviewer 3

We noted that the points raised by Reviewer 3 had already been addressed in our previous revision. Therefore, no additional modifications were required in response to these comments.