HBES Early Career Award Submission Deadline EXTENDED to June 1

We are extending the deadline for nominations (self and other) for the HBES Early Career Award until June 1. The Human Behavior and Evolution Society Early Career Award recognizes individuals for their contributions to the field.


Nominations are now due by June 1 2022.


See Awards for more details, eligibility information for the Early Career Award, and the link to submit nominations (under eligibility tabs). Note: Submission are NOT extended for the Lifetime Career Award.

Differences in Men’s and Women’s Friendships Cause Some Differences in Men’s and Women’s Friendship Jealousy

by Jaimie Arona Krems and Keelah Williams

If you’ve read about Gene and his best friend Phineas in John Knowles’ great American novel A Separate Peace, the women alums of Vassar’s class of ’33 in Mary McCarthy’s The Group—or work from Elena Ferrante, Sally Rooney, or pretty much any other author describing dyadic friendships in their wider social world—you’ve read about friendship jealousy. (See also the hilarious ‘Best Friend Toast’ scene from the movie Bridesmaids.) Just as romantic jealousy protects our romantic relationships from third-party threats (e.g., partners defecting to a third party, a third party poaching our partners), we’ve found that third-party threats to our friendships can give rise to feelings of friendship jealousy. But there are some differences in how friendship jealousy plays out across sex/gender.


Of course, as with many phenomena, men and women have more in common than not when it comes to friendship jealousy. We expected—and found upon re-analyzing some of the data from our previous work in U.S. samples—that the inputs and outputs of the friendship jealousy system are the same across sex/gender. The inputs to our friendship jealousy deal primarily with the value of the friend and threat of losing the friend. That is, feelings of friendship jealousy are sensitive to the irreplaceability of our focal friend. We feel greater friendship jealousy when best friendships are threatened than when only mildly close ones are. Feelings of friendship jealousy are also sensitive to the level of ‘replacement threat’ posed by the possible interloper (the person who might steal your friend). I would feel more friendship jealousy if Joel and I always worked out together in the mornings but he started working out with his new friend James than if Joel started to spent tons time socializing with James at work, or than if Joel started spending all his time with a new romantic partner. I’m not his work pal or partner, so he’s not replacing me in the latter instances. Rather, the more the interloper stands to take my place in Joel’s social relationships, the more friendship jealousy I feel. And these feelings of friendship jealousy can cause us to engage in friend guarding—behavior aimed at helping us maintain our friendships. Again, all of this holds across sex/gender.


But in a recent article, we also raised the question of when (and why) we might see sex/gender differences in friendship jealousy.


We began from the premise that common differences in men’s and women’s friendship structures and putative historical functions affect those inputs (and outputs) of the friendship jealousy system. Insofar as these aspects affect the inputs of the system, we should expect some sex/gender differences in friendship jealousy at the prospective loss of same-sex friends. (Because sex/gender segregation in friendships is the norm from early age, we focused on same-sex friends.)


We predicted—and found in samples of U.S. community participants and students—that women report greater friendship jealousy than men at the prospective loss of best friends.


Why? First, women tend to form extremely close one-on-one friendships with one other woman, whereas men tend to form looser multi-male friendship groups. If every person got 100 friend points to invest in friends, this would be like women putting 60 points into a best friend, say, and 20 points in two other close friends, whereas men put 20 points into five friends. This structural difference implies that the value, or irreplaceability, of women’s (versus men’s) best friends might, on average, be higher.


Second, women’s extremely close best friendships are not made overnight; they take much time and effort to form. Moreover, and third, women’s (versus men’s) extremely close friendships often involve a lot of self-disclosure (e.g., which bands I like, which colleagues I hate, tales about that embarrassing time I called my advisor “mom” in a lab meeting). This information is easy ammunition. If I lose my best friend to someone else, that person might learn all my dirty secrets. So, for women, it might be both more costly to replace a best friend and more costly to lose one to someone else.


Fourth, some work suggests that male’s multi-male friendship groups are actually protective against friend loss, and that women’s dyadic friendships are more prone to breaking up—making women’s friendships perhaps more vulnerable to poaching. Indeed, girls sometimes purposefully ‘break-up’ other girls’ dyadic best friendships to poach one of the newly-on-the-market friends, but we knew of no such attacks among boys’ friendships.


We could make a strong prediction that, when faced with their best friends becoming potentially closer to another friend, women might report greater friendship jealousy than men. And they did.


Our next two predictions, focusing on men, were more tentative. First, male (but not female) primates seem to have a long history of banding together in intergroup violence. The relative size of one’s coalition plays a gargantuan role in such conflicts. It’s possible, then, that for men even peripheral allies (e.g., acquaintances) would be somewhat valuable. That is, just as women might value a same-sex best friend more than men do, men might value a same-sex acquaintance more than women do. The size of the effect is small, but we do find that men report greater friendship jealousy at the prospective loss of same-sex acquaintances than women.


Second, this same logic suggests that contexts of intergroup conflict might amplify the value of men’s allies. Thus, we designed an experiment wherein some participants were told to imagine that their same-sex friends were also teammates with whom participants would face off against an opposing team. Moreover, these teammates were not only becoming potentially closer to another friend, but also to the opposing team. (Other participants were asked to imagine friends becoming closer to one’s same-sex rival.) We predicted and found that the intergroup conflict context amplified men’s reported friendship jealousy (at the prospective loss of friends-cum-teammates to rival teams). Again, though, this effect was small.


In all, the structures and perhaps historical functions of men’s and women’s friendships can bear on the inputs to the friendship jealousy system. For example, if I put most of my friendship eggs into a single best friend basket (versus multiple close friend baskets), it makes sense for me to be very sensitive to detecting and responding to threats to my best friend. By affecting these inputs—like the irreplaceability or value of the focal friend—these sex/gender differences in friendship seem to translate into some sensical sex/gender differences in friendship jealousy.


Read the paper: Sex (similarities and) differences in friendship jealousy

Rules of Descent Only Affect Women’s Marital Dispersal

by Ting Ji

Sex-biased dispersal is a widespread phenomenon in animals and humans. Different species show marked contrasts in the patterns of sex-specific dispersal. As for humans, we use the social norms of post-marital residence to regulate sex-specific dispersal at marriage. In most human societies, women leave their natal households and live with their husband’s kin (i.e. parilocality). However, neolocal residence is more popular in industrial societies, i.e. men and women form a new family separate from the kin of either side. Less common patterns include matrilocality, where men move to wife’s household, or ambilocality, where men and women can live with either side of the kin. In a few human societies, such as Mosuo in Southwestern China, the residence is duolocal (or natallocal), where neither men nor women disperse at marriage, husband visits his wife’s household at night, and returns home in the morning. In this society, both men and women live with their close relative for their entire lives. Patterns of sex-biased dispersal structure populations and determine whether an individual is surrounded by relatives or unrelated group members, and thus play an important role in shaping social behaviors.

What predicts the differences in sex-biased dispersal patterns in humans? Anthropologists have long noticed that there is correlation between different social structures in many regions. More specifically, patrilocality is usually associated with patrilineal descent, and matrilocality is associated with matrilineal descent. In other words, in patrilineal societies, descent is traced along male lines, men are more likely than women to remain in natal households, and women are more likely to marry out. In matrilineal societies, descent is traced through female lines, the opposite pattern thus can be found. Is there, however, a causal relation between these two types of kinship norms? Murdock has argued that certain descent systems might arise from different patterns of post-marital residence, i.e., changes of residence drive the change of descent. However, phylogenetic comparative studies show that co-evolutionary trend between these two cultural traits varies in each language family. Different mating systems and local competitions have been proposed to influence sex-biased dispersal as well.

Sex-biased dispersal in humans is also affected by ecological factors. Earlier studies have described dispersal patterns vary in populations with different modes of subsistence. In many hunting, gathering, and fishing societies (foragers), there is no strict rule about which sex should remain and which sex should disperse. Couples often change their residence from time to time. While in horticulture societies, both female-biased and male-biased dispersal are found. Dispersal patterns in pastoralism and agricultural societies, however, are overwhelmingly female-biased. The association between sex-specific dispersal and mode of subsistence has led to the hypothesis that the transition from foraging to agriculture and/or animal husbandry is likely to have promoted female migration. However, the evidence is mixed, with some research finding that the emergence of intensive agriculture, plow agriculture, or large domestic animals hindered matrilcoality and other research suggesting a male-biased dispersal system during the period of the introduction and intensification of agriculture.

As one of the largest language families, the evolutionary history of sex-biased dispersal in Sino-Tibetan has attracted much attention. However, archaeological and genetic studies provide mixed conclusions, and there is still much debate. Moreover, sex-specific models are needed to fully understand the evolution of human dispersal, as post-marital residence and sex-specific dispersal are not always interchangeable. Here we studied the evolutionary history of dispersal norms for males and females in Sino-Tibetan populations, using cultural phylogenetic comparative methods. And we also tested the coevolution of sex-specific dispersal and descent and subsistence.

We collected and analyzed ethnographic data on kinship norms and subsistence from 97 Sino-Tibetan populations. As in many other places around the world, women disperse and men remain in over 85% of the studied Sino-Tibetan populations. Women do not disperse at marriage (as in matrilocal or duolocal residence) in about 5.2% of all societies, whereas approximately 9.3% of the societies lack of strict norms on whether women should disperse or not.

We found that kinship descent likely co-evolved with female dispersal, but not with male dispersal. These findings suggest that in patrilineal societies, dispersal patterns for men are quite flexible, they can choose to move or remain in their natal households. Nevertheless, there is strict control over women’s dispersal. Our results also show that the state of “patrilineal/female disperse” is very stable, and women are unlikely to change their dispersal strategy in patrilineal societies, unless descent changes first.  We also found that female dispersal was likely ancestral, implying that the rare duolocal residence in Mosuo population, in which neither sexes disperse, evolved later. This result is consistent with an earlier genetic study suggesting that the Mosuo might have adopted matriloclaity recently. Furthermore, we found agriculture likely co-evolved with only female dispersal patterns, but the result is sensitive to alternative coding strategy. And we did not find association between domestic cattle and dispersal patterns of either gender. Our results thus illustrated how subsistence or descent can play different roles in shaping male and female dispersal behavior.



Read the paper: A phylogenetic analysis of dispersal norms, descent and subsistence in Sino-Tibetans

HBES 2022 Seeking Volunteers for Conference Support

#HBES2022 Still Virtually Everywhere conference is seeking volunteers from around the world to provide tech support, loading talks for speakers and moderating live Q&A after each talk.

HBES is offering a year’s free membership to volunteers.

Volunteers will receive training in using the platform.

Anyone interested should send the host, Leif, a message ASAP to kennair@ntnu.no

#HBES2022 Important Dates & Information

The host and program committees of #HBES2022 are excited to engage our members in an action-packed, fully customized, online conference experience. Here, you will find all of the information you need to join us (Still) Virtually Everywhere this summer!

HBES 2022 will take place June 22 – June 25. Specific time blocks will be announced soon

The conference will be open to only HBES members and registration will be FREE. You must still register for the conference using the registration form that will open June 1. If you’re not currently a member, please join or renew asap.


HBES Virtually Everywhere will be hosted on the ohyay platform and is a fully-customized online conference where you can 1) grab a coffee with colleagues before heading to a talk, 2) sing karaoke with your friends, or 3) discuss future collaborations at the hotel bar!

For the best virtual experience, we recommend all attendees use Chrome on a plugged-in computer, and strongly encourage the use of headphones so that everyone has a better auditory experience.

We look forward to seeing you all!

If you have questions, please contact the host and program chairs using this form.

Please bookmark the conference webpage for the most up to date information.


Mark your calendars! Here are the important dates you need to know:

  • Abstract submissions opens: April 15th, 2022 (limit one first-author submission per person of any type)
  • Review of abstract submissions will begin on a rolling basis: May 1st, 2022
  • Registration opens: June 1st, 2022
  • Abstract submission deadline and deadlines for New Investigator and Post-Doctoral awards: May 15th, 2022
  • Final abstract acceptance confirmation date: June 1st, 2022
  • Early Registration deadline: June 15th, 2022
  • Late Registration deadline: June 21st, 2022

Call for 2022 HBES Awards Open Until May 1

The Human Behavior and Evolution Society Early Career Award and Lifetime Career Award recognizes individuals for their contributions to the field. We are soliciting nominations (self and other) for each award.


Nominations are due by May 1 2022.


See Awards for more details, eligibility information for each award, and links to submit nominations (under eligibility tabs).



Roundtable Seminar on Evolving Solutions to Global Climate Change and Sustainability on April 25

We hope you will join us for the Roundtable Seminar Series event Monday, April 25th 2021 at 12:30 – 1:45 pm EDT where Drs. Talbot Andrews, Daniel Kelly, Anne Pisor, and Gonzalo Palamo-Vélez will engage in discussion, moderated by Dr. Tim Waring on the topic, “Evolving Solutions to Global Climate Change and Sustainability”. We’re looking forward to engaging with our members on important discussions happening in this area.

This series is an opportunity for HBES members to engage with experts on topics in the evolutionary behavioral sciences. Each virtual session will feature a panel of speakers answering questions from a moderator and live audience. Join us each month to discuss the big questions facing our field. Live sessions on the HBES ohyay space are open to registered HBES members only, but a recording will be made publicly available on Youtube after the event.

Please check your email for instructions to set up your ohyay account an access the HBES ohyay space that will be sent out on the week before the event.

Which Factors Best Explain Variance in Human Reproduction and Mating?

By Martin Fieder


Evolutionary biology has always been interested in the question, which individual traits influence how many children we have, and how much each of these traits contributes to it. As nearly every trait has to some extent a genetical basis, together with the progeny also the genes that are associated with any favorable trait are spreading – in evolutionary terms “the trait is under positive selection”.


It is meanwhile known that several traits influence how many children a person has, at which age a person becomes mother or father, or what the chances are that a person finds a mate. It is also established that the effects of those traits may differ whether the person is a woman or a man. Moreover, for some of these traits their genetical basis in terms of so-called polygenic risk scores has been determined, which enables us to estimate the liability of an individual for a certain trait. What has been largely neglected so far is the question, how much each trait contributes (in statistical terms how much variance is explained) to the number of children or the probability of finding a mate/being ever married. We therefore aimed to explore that issue and analyzed how much each single trait contributes to the individual variance of number of children and ever being married. As we used the Wisconsin Longitudinal study (WLS) for that analysis, ever being married is a rather good proxy for mating in general because participants in that data set are born between 1937 and 1940, as marriage was very common at that time in the US.


Among these analyzed traits are religious intensity (as it is known for its pro-fertile effect in both men and women), facial attractiveness as well as social status because social status in terms of income is also known to foster number of children in men though not in women. Our analyses showed that among men, this positive effect of social status on a man’s number of children can simply be explained by mating. Being married was by far the most important factor of having children in this data set. And the factor that contributed most to the fact, whether or not a person was ever married or not, was income (~18% in men and ~7% in women). The direction of that effect, however, differed between men and women. In men, higher wages were associated with a higher chance of ever being married. Accordingly, female preference for high social status in terms of high income predicted a man’s chances of marriage and hence, his number of children. In women, on the other hand, higher wages were associated with a lower chance of being married. We do not have a final explanation for the negative effect of income on ever being married in women, but likely the problem of combining family issues and career plays a role.


The effect of education, another indicator of social status, on marriage and reproduction was less straightforward. In both men and women of our data set, higher education predicted a lower number of children, which is in line with the literature and, due to postponing of reproduction, is particularly expected in women. Interestingly, in men but not in women, the genetic predisposition towards higher education (polygenetic score for general cognitive ability) had a small positive effect on the number of children. A more detailed analysis revealed, that in men, a higher predisposition for education/general cognitive ability was associated with higher income, which in turn predicted a higher number of children.


“Our data show that in men, social status in terms of income has by far the strongest effect on marriage and as a result on reproduction as well. This is a finding which is clearly in line with evolutionary assumptions, predicting that women should prefer men of higher social status for their own and the sake of their progeny”


The effect of all other analyzed traits on the number of children or ever being married was much weaker. Only facial attractiveness explained 6% of ever being married in women and 2% in men, which, however, is still lower than expected as facial attractiveness has always been reported to be an important determinant for mating.


Our data show that in men, social status in terms of income has by far the strongest effect on marriage and as a result on reproduction as well. This is a finding which is clearly in line with evolutionary assumptions, predicting that women should prefer men of higher social status for their own and the sake of their progeny. However, as income is a very recent indicator of social status we are not able to make any final conclusions on ongoing selection pressures in modern societies. On the basis of our data, we can just argue that men in modern societies seem to be under pressure to “earn money” if they aim to find a mate and to have children.


Read the paper: Contemporary selection pressures in modern societies? Which factors best explain variance in human reproduction and mating?

Men and Women Desire Some Different Features in Their Friends

By Jessica Ayers, Jaimie Krems, & Keelah Williams


We often focus our finite time, interest, and even research energy on mating and kin relationships rather than friendships. But across evolutionary history, friends have provided important benefits and helped us solve recurrent adaptive problems. For example, our ancestors’ friends helped them acquire resources, gain status, win social conflicts, attract and retain mates, and so forth. Further, friends help us when we are in need (and unlikely to receive help from strangers). As our time and energy to devote to these relationships is finiteit takes some 200 hours to make a close friend—we must choose in which friend(s) to invest our time and energy.


The qualities possessed by various friends can help us make these prioritization decisions. We invest in friends who have the qualities we most like. But what qualities do we look for in our friends?


Past work suggests that both men and women seek friends who are trustworthy, similar, familiar, generous, and who like us. Just as in work on romantic relationships, then, the qualities that men and women most want in partners are the same—even if there are some predicted, notable sex differences. But because there’s been much less of a research focus on friendship, we know less about the predicted, possibly notable sex differences in what people want in friends. That’s where we focused.


Building on previous work investigating evolved friend preferences, we reasoned that the nature and priority of the adaptive challenges (that friends help to solve) have been somewhat different for men and for women, and so some of the qualities that men and women value in friends might also be differently prioritized—again, even as many of the qualities men and women cherish in friends are the same.


In a series of three studies, we investigated (1) people’s preferences for ideal friends, (2) the actual qualities possessed by people’s real-life best friends, and (3) people’s prioritization when given a limited “friend budget” to spend on different qualities.


In Study 1, we asked 213 U.S. undergraduates to imagine an ideal same-sex friend and rate how important it was that this ideal friend possessed various qualities—qualities we created to reflect eleven different categories of adaptive problems. Men, as compared to women, more so reported that they wanted their ideal friend to be wealthy, have high status, provide access to potential mates, and be physically formidable. Women, as compared to men, more so reported that they wanted their ideal friend to provide emotional support, prioritize the friendship, help protect their romantic relationships, be an ally during conflicts, and provide useful social information. (We found no sex difference in the extent to which men and women valued ideal friends who actively tried to build their friendship networks or had unique skills/expertise.)


In Study 2, we aimed to assess how these preferences changed when participants reported on their actual same-sex best friend. We asked 306 U.S. adults to report the extent to which their real-life best friend possessed these traits. We largely replicated the results of Study 1. Men reported that their same-sex best friends were more likely to be wealthy, provide access to potential mates, and be physically formidable compared to women’s same-sex best friends. Women reported that their same-sex best friends were more likely to provide emotional support, help protect their romantic relationships, and be an ally during conflicts compared to men’s same-sex best-friends. (We again found no sex differences in the extent to which men and women reported that their same-sex best friend actively tried to build their friendship network or had unique skills/expertise.) However, we did not replicate the sex differences in status, prioritizing the friendship, and providing useful social information found in Study 1.


“We find that whereas men and women both benefit from friends with certain qualities (e.g., trustworthiness, intelligence), there have also been some recurrent, sex-specific challenges that men’s and women’s same-sex friendships helped to solve.”


In Study 3, we conducted a complementary assessment of friendship preferences using a self-report paradigm adapted from behavioral economics—the budget allocation paradigm, wherein participants are given finite budgets to spend on friendship qualities to create their ideal same-sex friend. When men and women are given large budgets from which to create their friends, we hypothesized that they would create similar ideal friends: When there is no constraint on the positive qualities an ideal friend can possess, people should want it all. When budgets are constrained, however, men and women are forced to prioritize the qualities they deem most important. We asked 250 U.S. adults to create their ideal friend using this paradigm. Looking at those choices under constrained budgets, we found that women, compared to men, (again) prioritized having a friend who provided emotional support and that men, compared to women, prioritized having a friend who had high status and provided access to potential mates.


We find that whereas men and women both benefit from friends with certain qualities (e.g., trustworthiness, intelligence), there have also been some recurrent, sex-specific challenges that men’s and women’s same-sex friendships helped to solve. By considering these pressures, future research can begin to investigate aspects of friendship—and, here, what we want in friends—that we can reasonably expect to be somewhat sex differentiated, such as the similarities and differences in how men and women maintain or terminate their friendships.



Read the paper: Sex differences in friendship preferences

The High Price of Low Status in Human Rituals

By Dimitris Xygalatas


What do peacocks and humans have in common? I suppose there may be other possible answers to this question, but one feature they do share is the use of extravagant, apparently senseless traits as a means of transmitting important information. When such transmission is beneficial to both senders and receivers, those traits will be favored by the forces of selection, even if at first glance they appear to be wasteful. In a nutshell, this is the core claim of costly signaling theory.


In the case of the peacock, the signal is built into its body. Its disproportionately long, iridescent tail is calorically expensive to produce, maintain, and carry around. It reduces agility, adds drag during flight, and makes its bearer a flashing target for predators. But as Darwin already noted, there is a method to this evolutionary madness. Although the tail itself may have no utility, the effort that goes into growing and maintaining it can still pay off. As only a fit peacock could afford to carry such a costly ornament and still be alive, peahens use this ornament as a reliable indicator of the male’s prowess. By selectively mating with males that carry extravagant tails, they are investing in good genes for their offspring, inadvertently pushing the males to grow ever more grandiose tails.


The same logic can also apply to behavioral traits. In humans, some of the best-known examples come from the domain of ritual.  Signaling theories of ritual argue that costly ceremonies help solve important coordination problems: for any group that requires cooperation among its members, information on people’s levels of commitment is crucial. But declaring one’s loyalty to the group is cheap. Paying a hefty membership price provides more compelling evidence of commitment to the group and its values. Actions speak louder than words.


There is mounting evidence in support of this view. For instance, empirical research shows that people who participate in costly rituals are more committed to group causes. This is not lost on community members, who perceive participation as a signal of prosocial qualities. However, unlike the indexical nature of the peacock’s tail (what you see is what you get), human signals are embedded in complex sociocultural contexts.


For the sake of simplicity, formal models of signaling typically assume that the intensity of the signal varies while all else being equal. But in reality, all else is never equal. Social inequalities may influence default perceptions of a sender’s quality, impacting the signal’s cost-benefit ratio. While previous research treated this variation as noise, we designed a study to quantify it.


Our study, reported in Evolution and Human Behavior, took place in the island of Mauritius during the Thaipusam Kavadi, a Tamil Hindu festival held in honor of Lord Murugan. Performed by millions of Hindus in India and around thew world, it involves several days of activities that culminate with a pilgrimage to the god’s temple. Before embarking on the day-long procession under the scorching tropical sun, devotees have their bodies pierced with metal needles, hooks, and skewers. They also carry large portable shrines called kavadi. Those are built on a wooden, bamboo, or metal frame supported on the shoulders and are decorated with flowers and peacock feathers (in serendipitous but seemingly emblematic fashion, the peacock is Murugan’s symbol). The word kavadi, which in Tamil means “burden”, is what gives this ritual its name – aptly, as those structures can often weigh as much as a person.


In this setting, we recruited 80 adult participants of various ages. We measured the size of the kavadis they carried and the number of piercings they endured. After they completed their pilgrimage, we also asked them questions about their religious beliefs and practices and gave them a survey to assess their socioeconomic status.


We found great variation in both the intensity and form of signaling: the number of piercings ranged from zero to 600, and kavadis varied from petite to gargantuan. The festival provides different signaling opportunities and, as it turns out, participants harness them according to their means. High-status individuals carried larger and more flamboyant kavadis — for those at the top third of the socioeconomic ladder, almost three times larger than those at the bottom third.


Why would that be? Quite simply, because they could afford to. Building and decorating a kavadi can be expensive: the most elaborate structures can cost the equivalent of three months’ salary of an unskilled worker. And those larger kavadis are not necessarily heavier (at least not proportionally), as the affluent can purchase better and more lightweight materials (e.g. aluminum in place of iron), which allows them to amplify their signals even further.


“During the ritual, low-status individuals on average put almost four times more needles into their bodies compared to the upper classes. Lacking the material capital to compete with the elites, those of low status turned to whatever other means were available to them: quite literally, their own blood, sweat, and tears.”


On the other hand, there was a negative relationship between socioeconomic status and frequency of participation: across their lifespan, low status individuals carried the kavadi over four times more often. But it was not just a matter of frequency: during the ritual, low-status individuals on average put almost four times more needles into their bodies compared to the upper classes. Lacking the material capital to compete with the elites, those of low status turned to whatever other means were available to them: quite literally, their own blood, sweat, and tears.


It is worth noting that across all these metrics, there was a large effect of gender. While most women had only one piercing, the median number for men was 79. Men also participated in the ritual more times over their lifetime and carried kavadis that were on average over twice as large. Unsurprisingly, then, the associations with socioeconomic status were even stronger when we looked at the male-only portion of our sample.


While the physically demanding aspects of the festival are mostly a male affair, this does not mean that women do not engage in commitment signaling — far from it. For instance, they are more likely to fall into trance, which can be a hard-to-fake signal of devotion. Moreover, women play key roles in parts of the ritual that are seemingly peripheral but socially important nonetheless, such as hosting and organizing elaborate family feasts at the conclusion of the festival — a laborious and time-consuming activity.


Our study was the first to quantify the multi-layered costs of an extreme ritual and their variation along socioeconomic lines. Our findings are in support of a costly signaling view of ritual. Needless to say, cultural practices are complex and cannot be reduced to monocausal explanations. Our study has merely scratched the surface of one of the most widely performed rituals in the world.



Read the paper: Social inequality and signaling in a costly ritual