Keep Calm and Protect Your Reputation

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– by Zihan Yang and Cory Clark

Crying may seem more like an act of vulnerability than aggression, but one person’s tears can tarnish two reputations. In a recent paper, we explored the reputational consequences of different emotion expressions in interpersonal conflicts. Across five studies and more than six interpersonal conflict scenarios (e.g., between colleagues, teammates, roommates, same-sex friends, romantic partners, neighbors), people who cried did the most damage to their conflict partner’s reputation but also suffered reputational damage themselves. In contrast, actors who kept their cool (what we call a “stoic display”) protected their own reputation but imposed fewer costs on conflict partners.

These findings suggest that tears and stoic displays pose opposite tradeoffs: crying undermines one’s opponent, but also oneself, whereas stoic displays protect oneself, but also one’s opponent.

Emotions have adaptive roles in humans’ lives and often occur within a dyad. They can serve important social functions by allowing humans to communicate their internal state to interlocutors and to interpret the internal states of their interlocutor. Past research has focused primarily on the reputational consequences for those who express emotion. For example, when an individual cries, this can help elicit emotional support but also can make the crier seem less competent (Barthelmas et al., 2024; Hendriks et al., 2008). Displays of anger can lead to status conferral but can induce fear at the same time (Tiedens, 2001; Yun and Jung 2022).

However, interpersonal conflicts occur when two parties have competing goals, and so emotions in such conflicts can signal information about both parties involved.  Because people are highly motivated to seek social information about others, when people observe interpersonal conflicts between two other people, they likely seek to understand how at fault each party is. Each party’s emotion expression can serve as useful cues as to who wronged whom and how severely. If one person yells or cries, third party observers might infer that that person is unhinged but also that they may have been wronged by their conflict partner.

We conducted five studies with over 3000 census-matched US participants and more than six interpersonal conflict scenarios, in which participants were randomly assigned to read that an actor cried, yelled, or maintained a stoic display (e.g., “dropped it and said nothing”). In Studies 1a-1c, participants read vignettes about interpersonal conflicts from the perspective of third-party observers, such as a noise complaint between two neighbors or a domestic dispute over one partner spending too much time at work. In Study 2, participants were asked to imagine themselves as the actor in an interpersonal conflict, such as receiving a seemingly unfair performance review at work. And in Study 3, participants were asked to recall real-life conflicts where their conflict partner displayed anger, sadness, or kept their cool.

Then we asked participants to evaluate the actor–the one who expressed the emotion–and the recipient–the conflict partner who received the emotion expression on items such as how blameworthy vs. praiseworthy they were, whether they seemed like a good or bad social partner, and whether they seemed like a good or bad person.

Across all studies, we found very consistent and strong effects that stoic displays were reputationally advantageous compared to crying or yelling. Actors were always evaluated the most positively when they kept their cool. However, when it came to the reputation of conflict partners, crying tended to damage recipient reputations more than stoic displays or yelling. Thus if one’s goal is to make a conflict partner look bad, crying does the most damage. These findings suggest that stoic displays and crying have opposite tradeoffs: crying damages the crier’s reputation, but also imposes costs on conflict partners, whereas stoic displays protect the stoic’s reputation but also do little damage to the conflict partner’s reputation.

We also observed that anger displays damaged the actor’s reputation compared to stoic displays and failed to damage the conflict partner’s reputation compared to tears. These patterns suggest that yelling primarily makes the yeller look bad. Anger displays likely serve other functions, such as intimidating interlocutors into acquiescence. However, these benefits come at a reputational cost: angry people are viewed as undesirable social partners.

Our studies did not directly test the psychological mechanisms underlying our results, but one possibility is that tears serve as evidence of harm. When someone cries, people may infer that the conflict partner caused harm to the person. At the same time, a person seen crying may be viewed as an unstable or needy social partner–a person who will take more than they give (see, e.g., Aquino et al., 2026). Calmness leaves less visible evidence of harm and makes the conflict seem more ambiguous. But maintaining composure in the face of conflict may be viewed as a temperamental virtue. Therefore, stoic displays can minimize perceptions of the hurt felt by the stoic, enabling both parties to avoid reputational costs.

The proverb “living well is the best revenge” is in some sense false. Merely carrying on through conflict poses minimal costs on conflict partners, but it does appear to be the best buffer against mutual destruction.

Zihan Yang & Cory J. Clark. Stoic displays have reputational benefits but fail to undermine adversaries. Evolution and Human Behavior 47 (2026): 106858.

References

  • Aquino, K., Thau, S., Graso, M., Clark, C., Lagios, C., Restubog, S. L. D., & Lu, T. (2026). The reputational consequences of victim signaling. Personality and Individual Differences, 250, 113515. https://doi.org/10.1016/j.paid.2025.113515
  • Barthelmas, M., Stockle, D., & Keller, J. (2024). On the social signal function of emotional crying: Broadening the perspective to social interactions in daily life. Emotion, 24(4), 960–974. https://doi.org/10.1037/emo0001313
  • Hendriks, M. C. P., Croon, M. A., & Vingerhoets, A. J. J. M. (2008). Social reactions to adult crying: The help-soliciting function of tears. The Journal of Social Psychology, 148(1), 22–42. https://doi.org/10.3200/SOCP.148.1.22-42
  • Tiedens, L. Z. (2001). Anger and advancement versus sadness and subjugation: The effect of negative emotion expressions on social status conferral. Journal of Personality and Social Psychology, 80(1), 86–94. https://doi.org/10.1037/0022-3514.80.1.86
  • Yang, Z., & Clark, C. J. (2026). Stoic displays have reputational benefits but fail to undermine adversaries. Evolution and Human Behavior, 47(4), 106858. https://doi.org/10.1016/j.evolhumbehav.2026.106858
  • Yun, D., & Jung, H. (2022). Anger expression in negotiation: The effects of communication channels and anger intensity. Frontiers in Psychology, 13, Article 879063. https://doi.org/10.3389/fpsyg.2022.879063

Why do so many cultures believe the body contains exactly 365 bones?

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– by Ze Hong

Open the Yellow Emperor’s Inner Canon, one of the founding texts of Chinese medicine, and you will find a curious claim: the human body contains exactly 365 acupuncture points, one for each day of the solar year. Turn to the Zohar, the central text of Jewish Kabbalah, and you will read that the body contains 365 sinews—again, matched to the days of the year. The Babylonian Talmud teaches that the Torah contains 365 prohibitions, one for each day. A ninth-century collection of Islamic hadith declares that every child of Adam is created with 360 joints. Ancient Indian Ayurvedic texts count 360 bones in the body, mirroring the 360 days of the Vedic ritual year. Medieval Irish penitentials prescribe 365 prayers, 365 kneelings, and 365 lashes of the scourge—because, they explain, this is proportionate to the number of joints and sinews in the human body.

The modern reader (I hope!) will notice something odd. The adult human body has 206 bones, not 365 or 360. Anatomically, none of these counts are correct. And yet cultures separated by thousands of miles and thousands of years arrived at strikingly similar claims: that the human body somehow encodes the calendar, that the microcosm of the body mirrors the macrocosm of the heavens. Why?

In my recent paper, I argue that these “numerological correspondences” are cultural manifestations of deep-seated features of human cognition. Once we understand the psychological machinery that generates them, their widespread appearance across unrelated civilizations begins to look far less mysterious. I identify four cognitive ingredients that, working together, make numerological correspondences intuitively compelling.

The first is pattern detection. Human brains are exquisitely tuned to find regularities in the environment—an ability that served our ancestors well in tracking prey, predicting seasons, and reading social cues. But this same capacity has a well-documented downside: we readily perceive structure even when none objectively exists. Francis Bacon put it beautifully back in 1620: the human mind “is of its own nature prone to suppose the existence of more order and regularity in the world than it finds.” When a body part count of “roughly a few hundred” is available for comparison with a solar year of 365 days, the mind can find a match with only a modest nudge.

The second is analogical reasoning through structure mapping. Humans are remarkably skilled at drawing analogies between conceptually distinct domains (think of the classic analogy between the solar system and the hydrogen atom, or between water flowing through pipes and electricity through wires). Cognitive scientists like Dedre Gentner have shown that we do this automatically and reliably, even as children. This capacity is a cognitive superpower for learning and creativity, but it also makes cross-domain mappings feel meaningful.

The third ingredient is a preference for simplicity, symmetry, and breadth in our models of the world. From an early age, children prefer explanations that unify many facts under a single cause. Adults do the same. We find symmetric theories more elegant, more satisfying, and more likely to be true. This preference is more than aesthetic decoration; it shapes what ideas we find plausible in the first place. The nineteenth-century chemist Newlands proposed his “law of octaves” partly because he was moved by the resemblance between chemical periodicity and musical scales. Aristotle accused the Pythagoreans of inventing an extra heavenly body simply because they considered ten the perfect number.

The fourth is a holistic worldview—the belief, common across many premodern civilizations, that the universe forms an integrated whole in which the body, the cosmos, morality, and nature are all interconnected. Where this worldview is culturally dominant, cross-domain numerical mappings are not merely permitted but expected. A correspondence between body parts and calendar days thus becomes evidence of a deeper cosmic unity.

These mechanisms together form a powerful engine. Pattern detection is the trigger, analogical reasoning is the bridge, symmetry preferences are the filter, and holistic cosmology is the epistemic foundation that makes the whole enterprise feel intellectually respectable. Once such a correspondence enters a culture, it also tends to persist. In everyday life, no one actually counts the bones in the human body. And within an authoritative religious or medical framework, why would you want to?

Why, then, do these ideas feel so implausible today? The answer, I suggest, is not that modern humans have somehow shed the cognitive tendencies that produced them. If anything, magical and symbolic thinking persist widely in secular contexts—from astrology apps to wellness fads. What has changed is the institutional environment and the epistemic influence it has on lay people. Modern scientific cultures reward empirical testing, tolerate the revision of theories in the face of anomalies, and cultivate skepticism toward claims that link the human body to the cosmos through symbolic analogies. Individuals raised in such environments learn to find “the body has 365 bones because the year has 365 days” not profound, but suspicious.

Ze Hong. The evolutionary-cognitive foundation and cultural persistence of menstrual taboos in human societies. Evolution and Human Behavior 47 (2026): 106899.

Sex-Specific Vulnerabilities

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– by David C. Geary

Sex differences are common across species and often related to sexual selection, that is, they are found for traits that influence intrasexual competition for mates and intersexual discriminative mate choices (Andersson, 1994). Sexually selected traits are often exaggerated in size or are physiologically demanding (e.g., of cardiovascular fitness) and thus are more sensitive to stressor exposure than other traits. For instance, sex differences in armament or coloration (e.g., plumage) are often driven by male-male competition or female choice, but these sex differences become smaller when males are exposed to stressors. This is because stressor exposure affects the exaggerated male trait more strongly than the same trait in females, although the same differential sensitivity should occur for traits showing a female advantage. The key, universal stressors are well captured by the Horsemen of the Apocalypse – poor or inadequate nutrition (famine), disease (plague), and intense social competition (war; or predation for prey species).

The same principles apply to humans and can be used to identify age-, sex-, and trait-specific vulnerabilities (Geary, 2015). The basic idea can test tested for populations and individuals: Evolved sex differences are larger in healthy populations, and the magnitude of these differences becomes smaller as living conditional deteriorate. My colleagues and I tested this hypothesis using data from two large multi-national studies. The first was a British Broadcasting Corporation (BBC) study that included two spatial measures that typically favor men and the second was a study that included an emotion recognition measure (The Eyes Test) that typically favors women (Greenberg et al., 2022; Lippa et al., 2010). We confirmed the originally reported sex differences and then plotted their magnitude across countries that varied on the Human Development Index (HDI). Individuals living in low HDI countries are more likely to suffer from infectious diseases, poor nutrition and a larger overall disease burden than are individuals living in high HDI countries (Emadi et al., 2021).

In a prior study, we showed that men’s advantage in height and weight – both sexually selected traits related to male-male competition and female choice – increased with increases in HDI scores (Giofrè et al., 2025). Thus, sex differences in height can be used as a proxy for national differences in developmental health, with smaller differences indicating that large portions of the population are exposed to nutritional and disease stressors. Within low HDI countries, the sex difference in height is larger for wealthier individuals than for individuals growing up in poorer contexts. Using this pattern and height data from the BBC, we showed that the BBC data are biased toward healthier samples in lower HDI countries and thus will underestimate cross-national sex differences in spatial cognition.

Despite biased samples, we found that the magnitude of men’s advantage in spatial cognition increased with national increases in HDI scores, just as men’s advantage in height and weight increase with improvements in living conditions; women’s advantage in lifespan increases in these same countries and thus the effects are sex- and trait-specific (Medalia & Chang, 2011). However, women’s advantage in emotion recognition was stable across countries. It could be that men’s spatial abilities are more sensitive to poor early and current living conditions than women’s competence at recognizing emotions, but this is unlikely. Other studies suggest that women’s advantages in social cognition are compromised by extreme nutritional deficits and are smaller when they grow up in contexts with poor general living conditions (Bora & Köse, 2016). Our null finding for the Eyes Test could have been due to biased samples for lower HDI countries, but we were not able to assess this possibility due to the lack of height data in the corresponding study.

In any case, these results and others like them have theoretical and practical implications. Theoretically, these studies show that evolved human sex differences are not fixed, but rather their magnitude varies systematically with current living conditions and conditions during development, just like with other species (Geary, 2015). As living conditions improve and societies become more liberal and gender equal, sex differences for many traits become larger (Halsey & Geary, 2025; Herlitz et al., 2025). This pattern is now well documented and refutes strong social-constructivist theories on the origin of sex differences.

More practically, sex differences in trait-specific sensitivity can be used to identify at-risk populations and could be used diagnostically at the individual level (Geary, 2015). For instance, women have advantages in verbal memory, but these competencies decline more rapidly in women than men with the onset of dementia. Men’s well-developed visuospatial abilities are more severely compromised than their verbal abilities with exposure to various toxins. In other words, evolutionary theory and sex-specific vulnerabilities could be used to develop assessments that are more sensitive to various stressors or cognitive declines than assessments based on the assumption that deficits are equally diagnostic for women and men. By analogy, we would not identify growth deficits using height or weight charts averaged across boys and girls. Rather, any such diagnosis needs to be based on sex-specific norms and same may apply to many more traits that show sex differences.

Geary, D. C, Giofrè, D., Collaer, M., Lippa, R. A., & Halsey, L. (2026). The vulnerable male brain: Men’s spatial abilities are condition-dependent, sexually selected traits. Evolution and Human Behavior, 47(4), 106901.

References

Do we have to choose between the quantity of friendships and their emotional quality? Maybe not as much as we thought

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– by Jessica D. Ayers & Diego Guevara Beltran

Friends are integral to our health, well-being, and survival. In fact, having at least one close friend does more for our longevity than quitting drinking, smoking, or picking up a steady habit of exercising. If just one friend is so good for us, why don’t people make as many friends as possible? One important reason is that our time and energy are finite–time spent making new friends cannot be spent doing other activities, such as helping family members, looking for potential romantic partners, or investing in our careers. The reality is that we often have to make difficult choices, not only about how much time to allocate towards making new friends, but also about how much to invest in our friendships. Is it possible that this decision reflects an underlying friendship quantity vs. quality trade-off, where our preferences influence how people navigate the social world?

 Our new paper published in Evolution and Human Behavior suggests that people may not sacrifice quality for quantity when it comes to their friendships. It seems that some people want it all: those who want many friends also typically report wanting intimacy with many of them, while those who want only a few friends are content having intimacy with just those few friends.

When we look at other domains of social life, we can see humans experience other quality vs. quantity trade-offs. For example, one trade-off includes whether to invest in having many offspring at the expense of their quality, or in having fewer offspring that are likely of higher quality. Another recurrent trade-off people experience is whether to invest in having many (potentially lower quality) short-term romantic partners, or having one (potentially higher quality) long-term romantic partner.

However, unlike monogamous mating relationships, where strong norms exist about exclusivity, there is no norm regarding the “appropriate” number of friendships one can pursue, explore, or maintain. Indeed, we can be friends with more than one person at a time, so that we can both invest in long-term friendships while also pursuing new potential friendships.

The similarities between romantic relationships and friendships inspired us to examine whether people experience a quantity vs. quality trade-off in their friendship making psychology. To this end, we created and validated the Friendship Making Orientation Scale by adapting the revised Sociosexual Inventory (SOI-R) to investigate friendship making psychology. Across five studies with over 5,000 participants, we determined the structure, validity, reliability, and cross-cultural generalizability of the scale.

The scale asks questions like “I enjoy making casual friendships with many different people“ and “I often wish others would introduce me to new people to talk to/hang out with.” These questions make up two underlying features of our friendship making psychology: preference for a wide friendship network, and desire for intimacy with many friends. Having established that these constructs are reliable and valid in US samples, we examined how these preferences related to participants’ actual friendships. On one hand, we found that people with a preference for having a wider network of friends tended to be more extraverted, had more friends, and had more friends willing to help them when in need. On the other hand, people with a stronger desire for intimacy with many friends reported having fewer friends, fewer of those friends were willing to help them, and being less satisfied with both the number and the quality of their friendships.

Yet, people with a higher preference for a wide network also scored higher in their desire for intimacy with many friends. This unexpected finding introduces a new puzzle: are people who want intimacy with many friends lacking in some aspect of their friendships? And if so, how could they also score higher on preference for wide networks–which is associated with a host of positive friendship outcomes? One plausible explanation is that desire for intimacy with many friends regulates friendship making motivations, increasing affiliative tendencies when one is below their desired friendship threshold, and decreasing such tendencies when one is above their threshold. Exploratory analyses suggested this may be the case; desire for intimacy with many friends was associated with friendship seeking motivations and behaviors for people who were both dissatisfied with their current number of friends and who scored high on preference for a wide friendship network.

Up to this point, our studies focused on American samples, limiting our ability to understand whether the idea of friendship making orientation travels well across cultures. To address this, we tested the Friendship Making Orientation Scale in a cross-cultural sample (Brazil, Egypt, and the Philippines, NTotal = 673), showing that the construct was applicable beyond American samples. Here, we confirmed the factor structure in a new cultural context and affirmed that the scale was associated with affiliative measures such as friendship quantity, prosociality, and closeness.

Although people make friends for many different reasons, the desire to make friends ultimately links back to their importance for our survival and well-being. The quality of our friendships is important because they provide crucial emotional and instrumental support. But having many friends is important too–a wider network of people can help us manage unpredictable risks, pool resources, provide protection, or even help us gain prestige. The time and energy needed to pursue these different friendship strategies have led researchers to believe that people experience a trade-off between these desires when it comes to their friendships.

And yet, our scale showed that the trade-off between the quality and quantity of friendships is not as clear-cut as once believed. Instead, it appears that people can have preferences for maximizing both the quantity and quality of their friendships without necessarily pitting these motivations against one another. However, whether people can actually have it all–many friends and emotional intimacy with all of them–without sacrificing their friendships or other important domains of life (such as mate retention or kin care) remains to be seen.

Jessica D. Ayers, J.D., Diego Guevara Beltran, Denise Mercado, and Athena Aktipis. “Friendship making orientation as indexed by preferences for wide networks and intimacy with many friends: structure and validity of a new construct.” Evolution and Human Behavior 47 (2026): 106878.

How Function Shapes Form

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– by Murillo Pagnotta

Symbolic artefacts as tools of the mind

In the study of human evolution, evidence of symbolic behaviour is often taken to indicate when the mind of our deep past relatives became equivalent to ours. While language is the ultimate yardstick of symbolic behaviour, in a broad sense this also includes other meaning-making practices such as drawing, sculpting, making ornaments, singing, and dancing. And while language does not fossilise, the production of materials laden with symbolic meaning can leave traces in the archaeological record.

Some of the oldest evidence of symbolic behaviour come from two well-known archaeological sites in South Africa. These are the engraved markings found in the ochre pieces from the Blombos Cave and the ostrich eggshell pieces from the Diepkloof Rock Shelter. These materials date back as far as ~100 thousand years ago and hint at a practice spanning tens of thousands of years. The engravings are widely interpreted as intentional markings. They are certainly not accidental—but what function did they actually serve? This has been a matter of debate among archaeologists and three main hypotheses have been proposed: the markings served i) a decorative purpose, ii) as markers of group identity, or iii) as denotational symbols (similar to a proto-writing system).

The basic motivation for our recent article published in Evolution and Human Behaviour is to generate experimental evidence for or against these competing hypotheses. Looking closely at the engraved patterns, they appear to have changed over time: earlier (older) patterns are simpler configurations of roughly parallel lines, while later (more recent) ones show complex patterns such as cross-hatching. We believe the structural properties of these engravings—and especially how they changed over time—might provide clues about their function. This work is actually the third in a series, so let’s view it in its proper context.

The cognitive profile of the Blombos and Diepkloof engravings.

In the first study in the series, the late Kristian Tylén and colleagues (2020) argued that symbolic artefacts such as the Blombos and Diepkloof engravings might be seen as ‘tools of the mind’—they can shape our thinking. The analogy is with instrumental tools, such as the stone cleavers, handaxes, and flakes our deep past relatives produced. Instrumental tools act on the physical environment and are often refined over time to better serve their function—stone flakes, for instance, became increasingly efficient cutting tools, and their structure reveal their basic function. Symbolic artefacts, by contrast, primarily act on perceptual and cognitive processes, facilitating reasoning, communication, and aesthetics in senders and receivers—and like instrumental tools, they too may be incrementally refined as they are repeatedly produced for the same purpose across generations. Our underlying hypothesis is that structural changes in symbolic artefacts can likewise reveal their function, all with cognitive implications that we can measure in the lab.

How can structural changes inform us about function? Tylén and colleagues hypothesised that each candidate function should map onto a distinct cognitive profile: decoration (hypothesis 1) predicts later patterns becoming more salient and purposeful-looking; group identity (hypothesis 2) predicts them becoming easier to remember and more stylistically distinct; denotational communication (hypothesis 3) predicts them becoming easier to discriminate within a set, so as to carry specific meanings efficiently.

To test these predictions, they designed five experiments measuring these cognitive implications: saliency, discriminability, style, intentionality, and memorability using drawings derived from early, intermediate, and late engravings as stimuli. They found that, over time, the engravings became more salient, more stylistically distinct, more intentional-looking, and easier to remember and reproduce—but no easier to discriminate within their own site and period. This cognitive profile points to decoration and/or group identity marking (hypotheses 1 and 2), but not denotational communication (hypothesis 3).

The cognitive profile of experimental transmission chain drawings—and back to the engravings.

This foundational analysis assumed that functional context constrains how artefacts change over time, with different functions producing distinct trajectories of structural change—and thus different cognitive profiles. Our two subsequent studies tested this assumption directly. Both studies followed a two-part approach. First, a transmission chain methodology generated lineages of related drawings: participants were assigned a position or ‘generation’ in a chain, shown drawings from the previous generation, and asked to reproduce them digitally after a short delay (the first participant in a chain saw drawings derived from the early engravings). In the second part of the study, a subset of these transmission chain drawings was used as stimuli in the same five cognitive experiments.

Our two transmission chain experiments different in the following way: One study implemented a simple delayed reproduction task to provide a baseline (Pagnotta, Tylén et al. 2026). We found that the drawings became increasingly regular, and this had cognitive consequences: they became easier to discriminate, looked more intentional, and became easier to remember—but their saliency did not change, and they became less stylistically distinct between chains. These changes appear to be shaped by working memory constraints, perceptual grouping, and other basic aspects of visual perception. In our latest study, we embedded the reproduction task within three functional contexts operationalising the three hypotheses: decoration, identity-marking, and denotative communication (Pagnotta, Wisher et al. 2026).

We found that different contexts indeed led to different cognitive profiles. For example, discriminability increased only under the denotative communication condition. Comparing the cognitive profiles of the transmission chain drawings with those of the original engravings, we found matching patterns suggesting that the original engravings were probably used for decorative or identity-marking functions—or, not inconceivably, a mix of these—but not denotative communication. These findings corroborate the conclusions from Tylén et al (2020).

In sum, these studies contribute to a growing corpus of experimental and quantitative evolutionary semiotics by showcasing how cognitive scientists and archaeologists can collaborate and use experiments to test competing hypotheses about ancient symbolic artefacts and the cognitive capacities they index.

This study was funded by the EU ERC (eSYMb, 101044626) and the Interacting Minds Centre (IMC) at Aarhus University.

Pagnotta, M., Wisher, I., Petersen, M. L., Riede, F., Tylén, K., & Fusaroli, R. (2026). The evolution of symbolic artefacts: How function shapes form. Evolution and Human Behavior, 47(5), 106902. https://doi.org/10.1016/j.evolhumbehav.2026.106902

References

Tylén, K., Fusaroli, R., Rojo, S., Heimann, K., Fay, N., Johannsen, N. N., Riede, F., & Lombard, M. (2020). The evolution of early symbolic behavior in Homo sapiens. Proceedings of the National Academy of Sciences, 117(9), 4578–4584. https://doi.org /10.1073/pnas.1910880117

Pagnotta, M., Tylén, K., Qvist, A.S., Kjeldsen, R.F., Rojo, S., Heimann, K., Fay, N., Johannsen, N.N., Riede, F., Lombard, M. and Fusaroli, R. (2026), Simulating Symbolic Evolution in the Lab: Potentials and Implications of Using Transmission Chains to Study Early Symbolic Behavior at the Emergence of Homo sapiens. Topics of Cognitive Science, 18: e70036. https://doi.org /10.1111/tops.70036

Pagnotta, M., Wisher, I., Petersen, M. L., Riede, F., Tylén, K., & Fusaroli, R. (2026). The evolution of symbolic artefacts: How function shapes form. Evolution and Human Behavior, 47(5), 106902. https://doi.org/10.1016/j.evolhumbehav.2026.106902

 

 

Beyond Death Anxiety: An Evolutionary View of Mortality Awareness

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– by Turan Gunduz, Hasan Gunduz, Erkan Eyrikaya and Hakan Cetinkaya

Death has long fascinated philosophers, biologists, psychologists, and many other scholars. Alongside questions about why organisms age and die lies another puzzle: human awareness of mortality. Humans can imagine the future and know that their lives will one day come to an end. How does such awareness shape our thoughts, emotions, and behavior? And why would a mind shaped by natural selection possess a capacity that appears so psychologically unsettling? Is mortality awareness simply a by-product of sophisticated cognition, or might it serve an adaptive function? While influential theories have emphasized the psychological burdens associated with mortality awareness, alternative perspectives are possible. As we will see, awareness of mortality may do more than generate anxiety. It may help individuals navigate adaptive challenges by shaping priorities in context-dependent ways.

For nearly four decades, Terror Management Theory (TMT) has been a leading framework for understanding how mortality awareness shapes the human mind and behavior. TMT views mortality awareness as an unwanted consequence of evolved cognitive capacity. According to the theory, awareness of inevitable death creates an existential anxiety that threatens meaning and effective functioning unless it is managed. To cope with this predicament, people are thought to embrace cultural systems, shared worldviews, social norms, and collective identities that provide meaning, continuity, and a sense of belonging to something larger and more enduring than the self. TMT further suggests that people may seek meaning and symbolic immortality through close relationships, parenthood, and family continuity. Indeed, a large body of research has shown that mortality reminders often strengthen adherence to group norms and negative reactions toward opposing viewpoints, while increasing interest in close relationships and desire for offspring.

These findings paint a compelling picture of how reminders of mortality can shape human thought and behavior. But might there be another way to read this story? Rather than viewing mortality awareness as a by-product, we wondered whether it might serve a more functional role. The crucial question, then, may not be how mortality-related concerns are reduced, but why they arise. Perhaps the discomfort associated with mortality awareness is not merely a problem to be solved, but part of a broader motivational system that evolved to direct attention toward challenges and opportunities relevant to ultimate evolutionary endpoints: survival and reproduction. From this perspective, stronger commitment to norms and cultural worldviews after mortality awareness may reflect adaptive responses that historically promoted survival through protection and social support. At the same time, findings involving close relationships and family continuity may point toward motivations related to reproduction.

This reasoning led us to a question that was both theoretically important and empirically testable: What happens when these two priorities come into conflict? Which goal takes precedence, and why?

From a modern evolutionary perspective, reproductive success is the ultimate currency of natural selection. Survival matters because it creates opportunities for reproduction, but survival without reproduction leaves no descendants. Although survival and reproduction often work together, it is reproductive success that ultimately helps explain much of the behavioral diversity. Given this, reminders of mortality may do more than motivate self-protection. By signaling that time and future opportunities may be limited, they may sometimes orient individuals toward strategies that increase reproductive success. Such a prediction is broadly consistent with Life History Theory, which suggests that cues associated with uncertainty and harshness can increase the importance of immediate reproduction. Yet in previous TMT research, participants were often given opportunities either to defend cultural worldviews and social norms or to express preferences related to close relationships or family continuity. So, studies typically examined survival-related and reproduction-related outcomes separately. What, then, happens when opportunities to support both adaptive priorities are simultaneously present?

To investigate this question, we drew on the methodological tradition of TMT research while adapting it to our evolutionary framework. Participants first reflected either on their own mortality or on a control topic. They then evaluated one of two scenarios involving divorce and remarriage. Although both scenarios violated prevailing moral norms, only one offered a clear reproductive benefit. In that scenario, an individual divorced an infertile spouse and later had a child with a new partner. In the other, the divorce led only to financial gain. This distinction allowed us to contrast two competing interpretations of mortality awareness. If mortality awareness primarily motivates people to defend existing worldviews, participants should become more critical of both behaviors following mortality salience. However, if mortality awareness functions as a cue that helps individuals navigate fitness-relevant challenges, and if reproductive success carries greater evolutionary importance than survival alone, then norm defense should weaken when it stands in the way of reproduction.

The findings supported the latter. Mortality reminders did not simply increase condemnation of norm violations. When the violation led to a reproductive outcome, participants evaluated it more favorably. When the same violation offered no reproductive benefit, evaluations became more negative. In other words, mortality salience did not produce a uniform tendency toward norm enforcement. Instead, responses varied depending on the adaptive implications of the behavior being judged.

Because reproduction is tied to sex-specific evolutionary pressures, we also examined whether these effects differed between women and men. They did. The shift toward reproduction-favoring evaluations was driven primarily by men. Because reproduction has historically involved greater obligatory parental investment and potentially higher costs for women, mortality cues alone may not be sufficient to trigger a faster reproductive strategy. Additional cues related to partner commitment and reliability may be needed before reproduction is prioritized.

Our findings challenge the common assumption that mortality reminders invariably strengthen moral and cultural norm enforcement. Instead, mortality awareness appears capable of selectively relaxing norm defense when norm violation facilitates reproductive success. Perhaps mortality awareness is not simply a source of anxiety. It may be the mind’s way of deciding what matters most when the future suddenly feels shorter. Future research examining how these effects vary across cultures, reproductive histories, and reproductive opportunities will contribute to a deeper understanding of how mortality awareness shapes the human mind.

Gunduz, T., Gunduz, H., Eyrikaya, E., & Cetinkaya, H. 2026. Mortality salience shifts moral judgment: reproductive motivations override normative defenses in males. Evolution and Human Behavior, 47(3), 106857.

More Friends, More Germs: How Disease Concerns Shape Our Social Circles

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– by Soyeon Choi

Much of the research on friendship focuses on its benefits. Friends are a major source of support, and people with closer, more supportive friendships tend to report better health and well-being. But friendship also has costs, including one that is easy to overlook: time spent with other people is also time spent exposed to their germs. Over evolutionary history, when infection could be deadly, a larger social circle likely meant both more support and more exposure.

This raises a simple question: do people who are more concerned about germs build different kinds of friendship networks? Our starting point was the behavioral immune system, the set of psychological responses that helps people avoid possible sources of infection before the body’s biological defenses have to respond. People vary widely in how reactive this system is. Some are highly germ-averse, readily bothered by uncovered sneezes or shared surfaces. Others hardly register such things.

We expected germ aversion to track how many friends a person keeps, but not evenly. Friendship is layered. Most people have a small number of very close friends, a somewhat larger group of close friends, and then wider circles of casual friends and acquaintances. These outer circles can be valuable, but the benefits of each additional tie are often less certain than the benefits of a close friend. Because of that, we expected germ aversion to matter most for the looser, more casual parts of the network.

Across four studies involving 2,266 participants, mostly in the United States but in one case across six countries on four continents (Brazil, Germany, Ghana, India, Kenya, and the Philippines), that is broadly what we found. People who were more wary of germs reported having fewer friends overall, and this pattern was especially clear among casual friends and acquaintances rather than close friends. The strength of the association also varied across countries, presumably due to differences in social norms, disease ecologies, and expectations around friendship.

Was this about what people felt they needed, or what they actually wanted? It was both. People higher in germ aversion believed they should have fewer friends and preferred fewer friends, particularly in the outer layers of the network. For many germ-averse individuals, then, a narrower network seems to reflect both perceived health needs and personal preference.

The same selectivity showed up in what germ-averse people expected from the friendships they did keep. They tended to hold higher and more fixed standards for friendship, especially when it came to what friends could do, whether they were similar, and whether they could provide practical help. When social contact feels costly, each friendship may need to “earn” its place more strongly. This selectivity also appears to be specific to friendships. In supplemental analyses, germ aversion was not associated with the number of family members or coworkers a person had. This makes sense: friendship is one of the more flexible parts of social life, a relationship category where people have more room to decide whom to keep close, whom to see less often, and which ties are worth maintaining.

Finally, we tested whether the perceived relationship between health and friendship goals can be shifted. Participants wrote about either the conflict between these goals, such as social gatherings increasing the chance of illness, or the ways the goals can support each other, such as friends helping someone recover when they are sick. Among people high in germ aversion, emphasizing harmony between health and friendship goals led to greater satisfaction with their friendships than emphasizing conflict. That is, seeing friends as part of staying healthy rather than as a threat to it appeared to ease the disease-related cost they attach to friendship.

Taken together, our findings suggest that germ aversion is not only about how people respond to strangers, crowds, or unfamiliar outgroups. It may also shape the ordinary social worlds people build and maintain day to day. As research on friendship continues to grow, we hope this work adds to the conversation by showing that the value of friendship is best understood alongside its costs, and that people differ in how they balance the need for connection with the need to feel safe and healthy.

Soyeon Choi and Joshua M. Ackerman. 2026. Infectious disease concerns predict narrow friendship networks. Evolution and Human Behavior 47(3): 106819.

Social context and the evolution of empathy

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– by Jeremy Garrison

We are a social species. Whether in the context of mammoth hunts, food sharing, child-rearing, war, or climate change, cooperation has always been instrumental to our individual and collective survival and propagation. Both the cooperation problems we face and our capacity to solve them are affected by our environments. Our capacity to accumulate and pass down socially learned behavior (culture) has allowed us to adapt to a wide range of ecosystems and organize into a diverse array of societal configurations. These different environments shape the genetic and cultural evolution of preferences through selection and their behavioral expression through context. For example, two people (with different genetic and cultural inheritances) may behave differently in any given context, and any given person may behave differently in different contexts.

One important way environments differ across societies is the social context of economic interactions. Do you know who made your clothes, your house, your tools, and your food? If you are a hunter-gatherer, you probably do. If you live in a market society, you probably don’t. We might call this the degree of social embeddedness or the average anonymity of the economic environment. How does this aspect of human ecology influence cooperative behavior?

In economic experiments where interacting subjects choose whether to act cooperatively or selfishly, highly social contexts promote cooperation. Cooperation increases when subjects are identified, when the interaction is face-to-face, when subjects can communicate, and when subjects are closer in real-world social networks. Additionally, in questionnaires of hypothetical choices, people are willing to forego more money to help those who are perceived to be socially closer to themselves. This relationship between social proximity and cooperation is also described in the psychology literature on empathy.

Empathy is a cognitive, affective, and/or behavioral response of one individual to the state of another. Empathic responses increase with familiarity, similarity, past experience, and salience. So, the strongest empathic responses occur between close friends or family and the weakest between out-group strangers. Cognitive and affective empathy are often associated with cooperative behavior. How might empathy have evolved?

In general, the evolution of cooperation is a puzzle since the actor is separated from the benefits of their action. If individuals interact randomly and always cooperate or never cooperate, the payoff of the non-cooperators is inevitably larger than the payoff of the cooperators, who pay the cost of cooperation. For cooperation then to evolve, the benefits of cooperation must be sufficiently concentrated among cooperators. This can occur via assortment, where cooperators interact disproportionately with other cooperators, or via discrimination, where cooperators can tell who the other cooperators are and cooperate only with them. These mechanisms can produce innate cooperative behavior through genetic evolution as well as socially learned cooperative behavior through cultural evolution. And they can manifest in a variety of proximate motives such as social emotions and moral norms.

To analyze the evolution of empathy, I developed a theoretical model consisting of an evolutionary game that takes place on a network with two different layers. Game interactions occur on the economic layer, and behavior transmission and empathy occur on the social layer. Previous literature shows that static networks can promote cooperation because interactors may have obtained their strategy from one another. But separating the transmission and interaction networks undermines the evolution of cooperation by reducing this assortment. So, unconditional cooperation relies on highly social contexts to evolve. But what if cooperation is conditioned on social proximity?

I model empathy as the game theoretic strategy of cooperating contingent on proximity in the social network. To explore the effects of social context on the evolution of empathy, I vary the overlap of the economic and social layers and analyze the evolutionary success of empathy. I employ both numerical methods—where I run many simulations and count the number of times the cooperators win out—and analytical methods—where I use a technique called pair approximation to derive a rule for the conditions under which empathy will evolve.

The numerical and analytical results align: unconditional cooperation relies on highly social economic environments and large gains from cooperation to evolve, but empathy can evolve even in asocial contexts as long as the gains from cooperation are sufficiently large. Specifically, I find that empathy evolves when (1/s)*b > c , where s is the number of social neighbors each player has and b and c are the benefits and costs of cooperation, respectively. What is the intuition for this rule (which so closely resembles Hamilton’s famous rule)? The degree of assortment in the social layer is inversely proportional to the number of social neighbors (the probability I learned my behavior from friend A is one divided by the number of friends I might have learned from). This then determines what proportion of the benefits of cooperation falls on other cooperators. If it’s greater than the cost of cooperation, empathy evolves.

In summary, cooperation can evolve when its benefits are concentrated among cooperators. If strategies spread among familiars by social learning or genetic transmission, then familiars tend to behave similarly. So, decreasing overlap of social and economic networks lessens assortment, impeding the evolution of unconditional cooperation. Conditioning cooperation on familiarity—which I call empathy—is adaptive in this context. Since familiarity is a proxy for behavioral relatedness, empathy concentrates the benefits of cooperation among empathizers, allowing this behavior to persist and spread. However, as anonymity increases, empathy results in less cooperation. Consequently, anonymous and impersonal economies may undermine cooperation, either by selecting for self-interested preferences or by rendering empathy nonfunctional.

In simpler terms, you probably act similarly to the people you know since we learn from the people around us. Cooperative people are therefore more likely than selfish people to be surrounded by other cooperative people. In this context, cooperating only with the people you know results in cooperative people reaping the benefits of cooperation and selfish people missing out. But if you use this rule when you don’t know anyone you interact with, you end up acting the same as a selfish person.

Jeremy Garrison. 2026. Social context and the evolution of empathy. Evolution and Human Behavior 47(3): 106838.

Revisiting Man the Hunter

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– by Haneul Jang

For decades, the phrase Man the Hunter has occupied a central place in discussions of human evolution.

Today, however, the phrase sounds outdated, evoking a familiar image of men hunting large game while women gathered plants and cared for children. The phrase is often seen as representing overly simplistic and male-centered evolutionary theories.

So why would a diverse group of contemporary anthropologists want to revisit it?

That question sits at the center of our recent paper published in Evolution and Human Behavior. In the paper, we ask what Man the Hunter (hereafter, MTH) has actually meant over time, and why the idea has remained so influential and so persistently debated for decades.

Our author team brings together anthropologists working across ethnography, archaeology, evolutionary theory, psychology, and human behavioral ecology, studying past and present hunter-gatherer societies. We approached MTH from different perspectives, reflecting the broader range of approaches that now shape research on human evolution.  My own work focuses on women’s foraging and cooperation among Bayaka hunter-gatherers in the Congolese rainforest, which shaped the way I think about subsistence, cooperation, and human evolution.

What Does Man the Hunter Really Mean?

What we found is that MTH was never just one thing.

The term has referred to both an evolutionary framework and a broader cultural narrative about human nature itself. Many discussions of MTH collapse several distinct meanings together: the original 1966 Man the Hunter conference and edited volume, popular portrayals of hunting-centered evolution, and debates within human behavioral ecology about hunting, gathering, and the division of labor in human societies. Distinguishing among these meanings and contexts helps explain why the debate has persisted for so long.

But perhaps more importantly, the debates surrounding it inspired many research programs that later expanded and revised it, including research on cooperation, food sharing, subsistence practices across past and present societies, and the ecological and social factors shaping divisions of labor.

In other words, the history and legacy of MTH are more complex and more scientifically productive than they are often portrayed.

Hunting Was Important, but Never the Whole Story

Early anthropologists studying hunter-gatherers were understandably fascinated by hunting. Hunting is dramatic, risky, and highly visible. Large-game hunts demand coordination, planning, technological skill, and food sharing, all deeply relevant to understanding human evolution. As a result, hunting became central to many theories about how humans evolved.

But even in the early discussions, it was clear that hunting was rarely the only source of food. At the Man the Hunter conference, the importance of plant foods and women’s gathering was already emphasized. Gathered foods provided a substantial, and often dominant, portion of daily calories, while the balance between hunting and gathering varied across ecological settings.

In other words, debates about women’s subsistence labor and the diversity of foraging economies were not external critiques added later. They were already part of the scientific discussion surrounding MTH.

Yet this broader picture was often reduced to a much narrower image of ‘men evolved by hunting’.

Over time, this stereotypical image was increasingly challenged. Archaeologists and ethnographers documented more flexible divisions of labor than earlier theories suggested. For example, research among Agta hunter-gatherers in the Philippines documented women hunting with bows and arrows, while work among Aka foragers in the Central African Republic documented simultaneous cooperative labor and childcare among men and women. Across societies, both women and men contribute to subsistence in flexible and complementary ways, and women’s labor has long played a central role in household provisioning. Childcare, food processing, and food sharing are also recognized as central to understanding human evolution. Importantly, many of these findings emerged from the same questions that originally motivated interest in hunting: how humans cooperate and survive in challenging environments.

Human Cooperation Beyond Simple Divisions of Labor

I have been studying cooperation among Bayaka women in foraging, childcare, and knowledge transmission, focusing on women’s central roles in subsistence and support networks that also involve children through age-graded learning and cooperation. From my perspective, one of the most productive outcomes of the MTH tradition was that it pushed anthropologists to think seriously about how people depend on one another in everyday life.

Why do people cooperate beyond immediate kin? How is food shared across households and generations? How are childcare, foraging, and provisioning coordinated within everyday social life?

These questions cannot be answered by focusing only on hunters or only on gatherers. Human subsistence systems rely on many interconnected forms of labor and support.

For example, successful subsistence often depends on broader systems of social support that include foraging, childcare, food processing, and food sharing. Both hunting and gathering require extensive ecological knowledge, planning, and coordination with other group members. The evolutionary success of humans likely depended not on one sex performing one heroic task, but on the ability of groups to flexibly combine many complementary forms of labor.

In this sense, revisiting debates surrounding MTH does not mean either glorifying or dismissing them. It means understanding how these debates inspired later research that broadened and reshaped earlier ideas about human evolution. Questions surrounding women’s labor and cooperation, which received relatively little attention in the original MTH discussions, motivated multiple lines of research on the importance of women’s subsistence work in evolutionary history. These questions also became central to research on childcare, provisioning, food sharing, and social interdependence, including influential work by scholars such as Sarah Blaffer Hrdy on cooperative childcare.

That is why reducing the conversation to “Was MTH right or wrong?” misses the larger issue. A more important question is how these debates pushed anthropology toward a broader understanding of cooperation, subsistence, and the many forms of labor that shaped human evolution. But to understand that legacy, we need to understand the historical context in which these debates developed.

By revisiting the history of MTH, our paper highlights how scientific debates about the past continue to shape the questions we ask about what made us human.

Vivek V. Venkataraman, Edward H. Hagen, Duncan Stibbard-Hawkes, Raymond Hames, Sheina Lew-Levy, Haneul Jang, Luke Glowacki, Jordie Hoffman, Karen Kramer, Helen Elizabeth Davis, Kathrine Starkweather, Barry Hewlett, Zachary H. Garfield, and Robert L. Kelly. 2026. The Meanings and Dividends of Man the Hunter. Evolution and Human Behavior 47(3): 106840.

Can we trust the cheap excuse: “I didn’t intend to do it”?

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– by Yohsuke Ohtsubo

When you inadvertently step on someone’s foot, what would you say or do? Perhaps, you would say something like “Oops, I’m sorry. I didn’t intend to do that.” Most likely, both you and the other person would find it sufficient. People around you also expect that the other person would respond with something like “never mind.” If you tried to do something more costly, such as kneeling down or offering money to seek forgiveness, people might find it weird.

But suppose that you decline a donation request for victims of a recent massive hurricane. Perhaps you did not have any cash with you at the time; perhaps you had already made a large donation shortly before; or perhaps you do not like the organization because you oppose its past activities. What if you have to decline it in the presence of many friends who are making donations? Unlike the first example of stepping on someone’s foot, your reputation is at stake, and you may not feel that simply saying “I am not stingy” would do all the work.

If you didn’t have any money at the time, you might want to make a donation on another occasion, preferably in the presence of some of the friends. If you had already made a donation, you might prove it by showing a certificate or receipt, if you have one. If you oppose the organization, you might later donate to a different organization and somehow try to let your friends know about it.

If you find these scenarios realistic to some extent, that is because having a reputation as a good person is essential to our social lives. Moreover, that is because we, implicitly or explicitly, know that cheap talk is not credible when something important is at stake. If you could convince your friends simply saying, “I am refusing to donate not because I am stingy, but because blah blah blah,” everyone would do so. They would justify unkind or even mean behavior by offering a cheap excuse.

The preceding paragraph makes two points. First, having a reputation as a good person is important. Second, some costly acts are needed to maintain it. The first point has been intensively studied under the rubric of indirect reciprocity. However, the indirect reciprocity literature has paid much attention to how audiences assign a good or bad reputation to a focal actor. In contrast, little attention has been paid to how focal actors respond to their own reputational predicaments.

We found this to be lacking in balance and developed a model of indirect reciprocity including an option for the focal actor to maintain their reputation. In the standard model of indirect reciprocity, each donor has just two options: to help or not to help their partner. If you help your partner, you are regarded as a good person, and someone else will help you in the future (hence the term “indirect” reciprocity). The flip side of this is that if you decline to help your partner (maybe because you regard them as a bad person), your reputation becomes bad, and you will not be helped by others.

In the standard indirect reciprocity models, each actor’s reputation is entirely determined by others’ reputation-assignment strategy. An actor in the donor role can choose only whether or not to help their partner. After that, they must simply wait and see how others evaluate their behavior. In reality, however, people take various actions to maintain a good reputation. For example, if you decide not to help the current partner because you consider them a “bad” person, you may instead donate to a charitable organization an amount of money equivalent to what would have been needed to help them, to signal that your intention is not bad. We empirically tested this idea in our previous work, in which participants were given a third option—abandoning the endowment that they could have used to help their partner. We observed that participants spontaneously used this option to signal their good (or not bad) intention to others.

An implicit assumption of such signaling models is that the reputation maintenance signals (e.g., donating money to a charitable organization or abandoning an endowment) are costly. Theoretically, this cost is required to make the signals credible. Because of this cost, no one could fake such signals (i.e., by claiming good intentions while having in fact decided to keep the endowment for oneself). However, it has not been empirically tested whether people would abuse a signaling system if it were free.

In our new experiment, participants were given an option to turn on a light on their experimental game screen, which could be observed by other participants. Half of them were allowed to use this option for free, while the other half were required to pay an amount equivalent to what would have been needed to help the current partner. In the free signal condition, participants in fact abused the signaling system. When the signal was costly, it tended to be used to honestly communicate their good intentions. However, when it was free, the signal carried little information about the signalers’ intentions.

In sum, our new study provides empirical evidence for the proverb “actions speak louder than words,” especially in the context of reputation maintenance or self-presentation. When you see someone’s wrongdoing and hear them say, “I didn’t intend to do it,” you may doubt it. Your doubt has empirical support!

Tanaka, H., Miyazaki, Y., & Ohtsubo, Y. 2026. Dishonesty of cheap reputation signaling in indirect reciprocity. Evolution and Human Behavior, 47(3): 106856.