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.

When Love Feels at Risk: The Hidden Logic of Jealousy

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– by Ana María Fernandez, María Barbato, Michele Dufey

Jealousy is often portrayed as irrational, possessive, or simply unpleasant. Yet from an evolutionary and developmental perspective, jealousy may be better understood as a socially intelligent alarm system: an emotion that becomes activated when a valued relationship appears to be threatened by a third party. In our study, we tried to “switch on” this alarm in a controlled way, by presenting concrete decisions about how partners distribute resources between their romantic relationship and a potential rival.

This alarm system does not begin in adulthood. It can be observed early in life, when infants protest the apparent loss of a caregiver’s attention to a sibling or another person. Later, in friendships, jealousy may emerge when a newcomer threatens to replace our special place in a best friend’s affection.

Romantic jealousy follows a related logic; it is commonly understood as a response to threats of sexual or emotional infidelity. But beneath these familiar scenarios lies a broader question: what exactly is being protected? From an evolutionary perspective, romantic jealousy may function to protect exclusive access to a partner’s affection, attention, time, commitment, and investment. It is not only about sex, but about the possibility that a partner’s valued resources—emotional, social, reproductive, or material—may be redirected toward a rival.

This broader view motivated our research. For many years, studies of romantic jealousy relied heavily on hypothetical forced-choice scenarios, especially those contrasting sexual and emotional infidelity. We wanted to move beyond asking people to imagine betrayal in the abstract. Instead, we sought to create a more interactive experimental situation in which jealousy could be evoked through the allocation of resources. The economic game we used was designed to capture exactly this sense of being chosen, how much “goes to me” versus “goes to someone else” becomes a simple but powerful signal of where a partner’s attention and commitment are directed.

So, we invited romantic couples to the laboratory and used a modified economic game inspired by the dictator game. Participants were led to believe that their partners had exchanged resources with anonymous opposite-sex individuals. The game allowed us to model two different kinds of rival-related threats.

In the first condition, which we will call emotional investment, participants were informed that their partner had given most of their available resources—75 out of 100 dollars—to an opposite-sex person they had just met, rather than to the participant. This situation was designed to represent a partner actively directing resources toward a potential rival, and evoked the highest jealousy overall, and it was stronger among women than men.

In the second condition, which we will call mate poaching, participants were told that an opposite-sex person, already in a relationship, had given most of their resources to the participant’s partner, at the expense of their own partner. This was designed to represent someone else attempting to invest in, attract, or “poach” the participant’s partner, and it tended to evoke more jealousy among men than women, although the effect was weaker than expected

Importantly, we also included control conditions. These allowed us to examine whether participants were simply reacting negatively to any unequal allocation involving the opposite sex. The answer was no. Jealousy was not merely a response to unfairness, generosity, or discomfort with resource exchange. Rather, jealousy was especially heightened when the allocation implied a possible shift in relational investment: when a loved one appeared to give more to someone else than to the participant.

This is the central novelty of the study. Romantic jealousy may be triggered not only by explicit sexual or emotional betrayal, but also by subtle signs that a partner’s investment is being redirected. A simple economic decision—who receives more, who gives more, and at whose expense—can carry relational meaning. It may signal closeness, preference, availability, or threat.

Why does this matter? Because jealousy is often studied as if it belongs only to adult romantic life. Our findings suggest that jealousy may be part of a broader relational system that develops across the lifespan. From infancy to friendship to romantic love, jealousy appears when a valued bond feels vulnerable to displacement. It protects not only mating interests, but also attachment, exclusivity, affection, and the expectation that we hold a special place in another person’s mind.

By using an economic game, our study offers a new way to examine jealousy experimentally. It also helps refine the evolutionary interpretation of jealousy. Going beyond basing jealousy on sex differences or infidelity scenarios, the findings point to a more general mechanism: jealousy is activated when the exclusive investment of a significant other appears to be at risk. Jealousy-related feelings should also be placed in a constructive relational perspective. They do not reflect conflict or insecurity alone; they may also signal that closeness, attention, and commitment matter, and motivate healthy ways to protect them.

The green-eyed monster, then, may not be merely a destructive force. It can also be seen as an evolved emotional signal, alerting us when a valued bond feels less secure, less exclusive, or less reciprocally invested than we expected. In this sense, jealousy reveals something deeply human: our need not only to love, but also to feel chosen, valued, and uniquely held in the mind of another. When understood constructively, jealousy may become less a threat to relationships than an invitation to reflect on what our closest bonds require to remain secure, reciprocal, and meaningful.

Ana María Fernández, María Teresa Barbato, Michele Dufey, Belén Zavalla, María Luíza Rodrigues Sampaio de Souza. 2026. Resource allocation and romantic jealousy: An experimental test of sex differences using economic games. Evolution and Human Behavior 47(2): 106816.

Why are humans so intelligent?

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– by Jonathan Egeland, Leif Edward Ottesen Kennair, and Thomas Haarklau Kleppestø

A central puzzle in the evolutionary behavioral sciences, studied since Darwin, is how to explain our uniquely human intelligence. Why did it evolve? What made it useful enough to be favored by selection? And what is the proximate explanation for how it works? Our recent paper in Evolution and Human Behavior argues that reciprocal cooperation holds the key to answering these questions.

Over the second half of the twentieth century, many researchers came to think that human intelligence has to be understood in light of the social environments our ancestors lived in. Humans evolved in groups, and surviving in those groups meant dealing with a great many kinds of social interaction throughout development. That basic idea is widely accepted. The harder part has been turning it into a clear, plausible, and testable explanation.

Our paper was an attempt to make progress on this issue. We focus both on what intelligence is for (its function), and on how this kind of explanation can be made consistent with relevant findings from personality research, psychometrics, and comparative psychology. We began by highlighting a simple coordination problem: how can the pursuit of individual fitness-related advantages be made compatible with social cooperation between members of the same coalition or group? In many other primate species, social life is characterized by dominance hierarchies. But in humans, cooperation is often the norm. A lot of research suggests that the coordination problem was solved by instituting a system of social exchange where individuals gain status by providing benefits to other group members. This is a form of reciprocity in which cooperation is established and maintained by repeated mutually beneficial interactions. In such a system, status will typically take the form of prestige rather than dominance, as voluntary deference is shown to individuals with traits or competencies indicative of what we call “coalitional value” (i.e., social partner value).

Our main claim is that intelligence­—or its behavioral effects, to be more specific—is one of the traits that signals this kind of value. Our Coalitional Intelligence Hypothesis proposes that the behavioral effects of intelligence reliably signal an individual’s ability to benefit others. Intelligence allows people to solve problems, generate useful ideas, coordinate activities, and provide other kinds of benefit to their group, and it grants prestige in return. This leads to several predictions, one of which is that intelligence should be positively related to prestige, and this relationship should be mediated by the extent to which individuals actually benefit their social partners. In slightly technical terms, intelligence enables reciprocal exchanges of status and cognitive-computational services.

Although there are many studies whose results are consistent with this prediction, few, if any, provide direct tests of it. For example, research from psychometrics and personality psychology shows that intelligent individuals achieve higher status, in part because they provide social benefits. However, status in these studies is operationalized in terms of socio-economic status (i.e., income, education, and occupation), rather than prestige. On the other hand, there are many findings from anthropology linking the relevant variables, but intelligence is usually measured subjectively and not in terms of actual cognitive performance. Future tests of the hypothesis should therefore focus on whether cognitive performance leads to higher prestige, mediated by ability to benefit one’s social group.

In addition to discussing what the hypothesis predicts and how it compares to other, established hypotheses from the literature, we also focused on whether human intelligence can be studied meaningfully as an evolved trait. Some researchers have argued that there is a single intelligence mechanism or system, while others see it as a loose collection of many different cognitive mechanisms; and the debate between these camps goes back more than a hundred years. However, we suggest that this may be a false dichotomy. At the level of underlying mechanisms, there is clearly a lot of heterogeneity. Human intelligence involves many different systems—there is no such thing as the intelligence algorithm—and claims to the contrary risk becoming incoherent. However, at the same time, research from comparative psychology and animal cognition suggests that human intelligence is made possible by increased computational capacity across a variety of underlying cognitive mechanisms. From this we draw two inferences: first, that intelligence can be “many” at the mechanistic level, while still for certain purposes being meaningfully conceptualized as “one” functional, higher-order trait; and second, it may be plausibly conjectured that individual differences in intelligence also are reflective of patterns of covariance in computational capacity across different cognitive mechanisms.

Taken together, our paper suggests that uniquely human intelligence evolved, at least in part, because it enabled reciprocal exchanges of status and social benefits. If people voluntarily defer to social partners providing them with useful services, then there can be selection for traits and competencies indicative of social partner value. As Richard Alexander once noted, ancestral humans living in such social environments had to “cooperate to compete”. One way of competing in this manner is to provide cognitive services to others, which intelligent individuals are better able to do.

Jonathan Egeland, Leif Edward Ottesen Kennair, and Thomas Haarklau Kleppestø. 2026. Coalitional Psychology and the Evolution of Intelligence. Evolution and Human Behavior 47(3): 106839.

Evolutionary and social functions of gaming

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– by Yago Moraes

Imagine two strangers meeting for the first time. Instead of making small talk, they either play an ancient strategy game or role-play a mild disagreement between friends. Weeks later, their impressions of one another have changed, but not in the way many theories about games would predict.

This puzzle lies at the heart of our paper, “Evolutionary and social functions of gaming”, which combines a lab experiment with computer simulations to ask: what are games for in human evolution?

Humans create games in nearly every culture and keep playing them long after childhood. This is striking because, although play is common across many mammals, gaming is different. Games have rules, goals, and winners-losers. They are also especially common among post-pubertal males and often reflect hunting, combat, and competition.

These features have inspired several explanations. Evolutionary researchers argue that games function as low-cost practice for hunting or warfare, and as arenas for status competition, helping players display skill, gain prestige, and attract mates. Social scientists, meanwhile, often emphasize a different role: games as social glue, capable of easing tension, breaking the ice, and fostering group cohesion.

My colleagues and I propose a framework that integrates these perspectives by extending Deaner and colleagues’ Allying with Coalitions Hypothesis. We suggest that games may have evolved not just as practice or entertainment, but as tools for finding valuable allies. In ancestral settings, success in activities such as big-game hunting or warfare depended on choosing reliable partners. A poor ally could be costly; a skilled and trustworthy one could be lifesaving. Games, with clear rules and measurable results, may have offered a low-risk way to judge others: Who is skilled? Who is strategic? Who cooperates well under pressure?

This idea leads to a clear prediction: if games help people judge potential allies, then playing together should speed up judgments of one another’s value and strengthen social bonds more efficiently than other activities.

To test this, we ran an experiment with same-sex pairs of strangers assigned to one of two conditions. In the gaming condition, participants played Nine Men’s Morris, a centuries-old strategy board game. In the control condition, they completed a role-play task in which two friends negotiated different preferences.

Across three sessions spanning roughly one month, participants repeatedly rated one another on two dimensions: perceived peer value (how desirable the other seemed as a potential friend or ally, including traits such as intelligence, charisma, attractiveness, and status) and relational proximity (how close and connected they felt to the other person). If gaming functions as an ally-selection mechanism, then the gaming condition should have produced faster or stronger shifts in these ratings. It did not.

Both activities changed how participants saw one another over time. Repeated interaction mattered, as expected. But gaming did not outperform the control condition. Playing a strategy game did not make strangers feel closer or judge each other more positively any faster than a structured, mildly conflictual conversation. This pattern appeared in both male and female pairs.

At first glance, this seems like a challenge to the hypothesis. But null results can still be informative. Rather than disproving the theory, the findings suggest that gaming’s social effects depend strongly on context. Not all games are equally informative. A low-stakes, one-on-one abstract board game played in a lab may be a poor model for the kinds of games that mattered in human evolution.

To explore this, we turned to simulations. In our model, virtual individuals could adopt either a gaming or non-gaming strategy. They formed alliances, completed risky cooperative tasks, survived or died based on performance, and reproduced across generations. This allowed us to test when gaming might become adaptive.

The simulations showed that gaming spread only under specific conditions. First, the initial gamer had to be above average in skill. Second, environmental risks had to remain meaningful by changing alongside population skill; otherwise, risks became too easy to overcome.

When low-skill individuals adopted gaming, the strategy usually disappeared. This is what we would expect if gaming functions as an honest signal: it benefits only those who can truly display valuable traits. The model also showed that gaming loses value when stakes are low. In safe settings where performance differences matter little, there is less reason for gaming-based assessment to evolve or persist.

This offers a plausible explanation for the experimental null results. Laboratory settings are not ancestral battlefields. No one’s survival depended on winning NMM or choosing the right lab partner.

Together, the experiment and simulations suggest a more nuanced view of gaming. Games do not reliably speed up friendship formation in low-risk, short-term interactions with strangers, at least not more than other structured social activities. But in conditions resembling ancestral life, where success in risky cooperative tasks affects survival, gaming may work as a stable strategy for judging and competing for valuable allies. This view helps explain the widespread presence of games, their male-biased participation in many cultures, and the modest social effects often observed in modern lab studies.

It also suggests we may be focusing on the wrong social phase. Rather than helping primarily to form friendships, games may be especially useful for maintaining them, for instance, by providing a controlled, nonviolent outlet for rivalry or conflict resolution. We refer to this speculative possibility as the Conflict Gambling Hypothesis.

Finally, not all games are created equal. NMM is an abstract, one-on-one board game. Many of the strongest sex differences and coalitional dynamics emerge instead in team sports and real-time multiplayer games such as FPSs or MOBAs, which more closely resemble the coordination, competition, and group dynamics of hunting and warfare.

By combining experiments with evolutionary modeling, this research offers a broader way to understand when games matter socially. It suggests that the evolutionary role of gaming is closely tied to risk, honest signaling, and the long process of building and maintaining alliances when stakes are high.

Yago Lukševičius de Moraes, Marco Antonio Correa Varella, Leonardo Cezar Silva Costa, Nayara Teles, and Jaroslava Varella Valentova. 2026. Evolutionary and social functions of gaming: Integrating experimental evidence and mathematical modeling. Evolution and Human Behavior 47(2): 106833.