The Evolution of Human Personality Roundtable Seminar Event on Sep. 27

We hope you will join us for the Roundtable Seminar Series event Monday, September 27th 2021 at 3:00 – 4:15 pm EST where Drs. David Schmitt, Aaron Lukaszewski, Julia Stern, & Alexander Weiss, will engage in discussion, moderated by Dr. Dario Maestripieri on the topic, “The Evolution of Human Personality”. 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 Monday September 20 2021.

The State of Evolution and Human Behavior: Potential for Future Collaborations Between Evolutionary Anthropologists and Psychologists

by Rebecka K. Hahnel-Peeters


There are many disciplines, subdisciplines, and paradigms through which to understand human behavior – two of which are evolutionary anthropology (EA) and evolutionary psychology (EP). At its core, the goal of EP is to understand the design features of the human mind shaped by natural selection to solve adaptive problems produced over evolutionary time (for review see Buss, 1995; Daly & Wilson, 1997). In a similar manner, EA uses the lens of evolutionary theory to analyze human behavior (both past and present; Fessler et al., 2016). Both EA and EP use the environment of evolutionary adaptiveness (Tooby & Cosmides, 1990) to inform theories of possible psychological mechanisms. However, EA and EP were founded on differing assumptions, and competition between these disciplines was motivated by (1) the differences in assumptions, (2) empirical methodology, and (3) limited time and resources to establish each discipline as serious scientific pursuits (Alden Smith, 2000)—all of which I review in depth here.

What are the similarities and differences between Evolutionary Anthropology and Evolutionary Psychology?

Similarities between the two disciplines include the study of human behavior, emotion, and cognition informed by adaptationist thinking; using comparative animal behavior to understand our behavior; and recognizing the importance of testing hypotheses in environments more like those of our ancestral past (Fessler et al., 2016).  Notably, researchers in both disciplines hold adaptive behavior resulting from mechanisms shaped by selective pressures reliably linked to distinct adaptive challenges (Barrett, 2015; Fessler, 2006).

Differences between the two fields have been characterized most heavily by  methodology. In many subdisciplines of EA, the focus of study has been on behavioral variance rather than the design features of the psychological mechanisms which produce our behavior (Alden Smith, 2000). Therefore, the main difference between EA and EP are their differing focal points (i.e., behavioral variation in different ecologies vs. the structure of cognitive mechanisms). This led to the differences in methodologies that characterize the fields today (e.g., anthropological field work and psychological lab experiments).

Evolutionary Anthropology and Psychology Are Complimentary

Since Alden Smith (2000) argued that EA and EP shouldn’t be considered competing disciplines and the recent 10th anniversary of Henrich et al.’s (2010) “the WEIRDEST people in the world” paper presented good reason to assess the state of the evolutionary social sciences, I conducted a content analysis of articles published in our society’s flagship journal. Henrich et al. (2010) highlighted a problem that most psychological research was based on WEIRD societies; because of this, we may expect increased collaborations between EA’s and EP’s in tests of evolutionary theories cross-culturally following the article’s publication.

Have Evolutionary Anthropologists and Evolutionary Psychologists become more collaborative?

Based on publications in EHB: not really (Figure 1). Across the 737 articles published between 2009 and 2020 there doesn’t seem to be an increase in collaborations between anthropologists and psychologists. In 2009, collaborations between anthropologists and psychologists accounted for 15.8% (n = 6) of the publications. The following years included between 2% and 18% of the publications with the mean rate of collaborations being 9.68% (n = 5.8).

Figure 1. Rates of collaborations between anthropologists and psychologists in EHB between the years 2009 and 2020.


How do evolutionary anthropologists and psychologists study phenomena?

Both use behavioral data and a variety of methods. Evolutionary anthropologists and psychologists do not appear to differ much in their use of behavioral data; however, the methods used to get these data were statistically different. There were significant differences in the methods used by anthropologists and psychologists. Anthropologists were more likely to use survey methods and field work than psychologists, and psychologists were more likely to use experiments in artificial environments (e.g., labs). Interestingly, it appears that psychologists started utilizing more methods to test their hypotheses after 2010. The variation in methodology started looking more like that of anthropologists (Figures 2 & 3).

Figure 2. Percentage of methods appearing in articles published by anthropologists in EHB between the years 2009 and 2020.



Figure 3. Percentage of methods appearing in articles published by psychologists in EHB between the years 2009 and 2020.



In the preprint, I discuss this project more in depth – including methodology, limitations, and future directions to understand the state of the evolutionary social sciences.

Interdisciplinary research—especially between complimentary disciplines—can strengthen our understanding of the world around us. EA and EP are uniquely positioned for collaboration, but the current state of EHB doesn’t show high levels of explicit collaboration between anthropologists and psychologists. It is possible that these two disciplines are becoming more collaborative implicitly; that is, they may be citing each other more, influence each other’s research questions and hypotheses, or evolutionary anthropologists may be training evolutionary psychologists (or vice versa).

Finally, we should continue to consider a roadmap for future collaboration suggested by Fessler et al. (2016). These four steps are attainable and could result in meaningful contributions to the field:

  1. Take advantage of existing literature within paleoanthropology and comparative animal behavior
  2. Read, cite, and understand ethnographic depictions of small-scale societies
  3. Utilize the electronic Human Relations Area Files
  4. Increase collaborations between evolutionary anthropologists and psychologists

Gendered Fitness Interests: Why people can hold political views that disadvantage their own sex

by Rob Brooks and Khandis R. Blake


The views of women and men can differ on important issues such as abortion, gender equity and government spending priorities. Surprisingly, however, average differences in sex on this front are often small. Many women adopt social and political positions that favour men and many men favour women-friendly positions.

In a recent paper in Evolution and Human Behavior we tried to make sense of this apparent paradox. We did so by understanding how people’s politics and practices don’t just track what’s good for them, but also what’s good for their relatives.

Election campaign games

A mere three days after his 2016 inauguration, US President Donald Trump reinstated the Mexico City policy, also called the “global gag rule”. The rule denies US health funding to foreign non-governmental organisations that provide abortions, refer patients for abortions, offer abortion-related counselling or advocate for more liberal abortion laws.

It wasn’t just Trump’s haste to reinstate the rule that galled pro-choice Americans. It was also the supporting cast of men Trump lined up for the photo-op.

Access to abortion is seen – and often spoken about – as a “women’s issue” as it impinges on women’s bodily autonomy and reproductive rights. But had Trump not been appealing to male voters, he could have gathered several prominent anti-choice women to stand behind him instead. Like Charmaine Yoest, former president of Americans United for Life, and soon-to-be appointed by Trump as Assistant Secretary of Health and Human Services for Public Affairs. Despite expectations and rhetoric, support for abortion is far more complicated than a simple tussle between the interests of women and men.


One of the first executive orders that Donald Trump signed was to reinstate the Mexico City Policy (also called the ‘global gag order’), concerning non-governmental organisations and abortion access. Donald J. Trump/Facebook


Think of the children

Polling conducted in the US by Gallup between 2018 and 2020 found 49% of men and 46% of women identified as “pro-life”. A similar gap was observed between “pro-choice” men and women, at 46% and 48% respectively.

“Pro-choice” policies give women options to control their own reproduction and, therefore, an important part of their lives. It would seem rational then for women to support these policies more than men.

Other policies relating to gender equity, sexual harassment, health-care spending and education also impact women and men differently. And while both genders’ views on these topics differ, the difference is quite small on average – in the order of 5%.

Variation of social and political views within a sex is actually far greater. While this is commonly thought to be due to differences in experience, we wanted to know whether the composition of a person’s family might change their views.

Our line of inquiry was inspired by a range of studies that have shown a child’s gender can change their parents’ views. For instance, firms led by male CEOs with daughters tend to adopt more socially and environmentally progressive corporate policies. They’re also more likely to appoint female directors and hire female partners, with positive effects on firm performance. On the other hand, male CEOs of Danish firms who fathered a son, rather than a daughter, paid their employees less generously and paid themselves more generously.

A similar pattern emerges in politics. In the US, legislators with daughters are more likely to vote for “pro-woman” laws than those with sons. And in both the US and Canada, parents with daughters favour gender equity more than those with sons.

Sometimes the effects become visible even before offspring have had much chance to experience the world. In one study, the birth of a son caused parents’ voting intentions to swerve immediately to the right, while a daughter prompted a swerve to the left. In another, the effects kicked in as soon as the parents learned their child’s sex at a prenatal ultrasound.

How your family’s composition can impact you

Research published by Laura Betzig and Lesley Hodgkins Lombardo in 1992 found people’s attitudes towards abortion varied depending on how many of their female relatives were in the age group considered “at risk” of unwanted pregnancy.

The more female relatives someone had aged between 15–50, the more likely they were to favour pro-choice policies. In turn, the more male relatives they had of a reproductive age, the more likely they were to support pro-life policies.

This study inspired us to consider whether gendered issues might depend not only on an individual’s own sex, but also the sex composition of their family. Humans, like other animals, are more invested in their close genetic relatives as a result of Hamiltonian kin selection.

We propose a new metric called “Gendered Fitness Interests”, or GFI. This not only looks at how many genetic relatives of each sex a person has, but also how closely related they are and how many potential reproductive years remain for them.

We built a simple model that confirmed out intuition that people with many close, younger female relatives (such as daughters and sisters) are expected to have a pro-female bias, while those with plenty of young brothers, sons or grandsons should have a bias that favours males.

In our model, sex differences in social and political attitudes are likely to be greatest in young adulthood, when a person’s own gender impacts them greatly. However, as an individual’s potential to have children diminishes, their current children and other relatives start to have a greater influence. Since most people have a balance of male and female relatives, this means a shift towards the centre.

Supporting Evidence

In the early stages of developing our model, long before we published it, a wonderful opportunity to test our ideas arose. For her PhD studies at UNSW, Maleke Fourati gathered data on attitudes towards Islamic veiling practices in Tunisia, specifically on mandatory veiling, which is one of those gendered issues on which we expect women and men might differ. Maleke’s data provided an early test of our idea of gendered fitness interests.

As we predicted, men were more likely than women to support mandatory veiling. But women with more sons (male-biased GFI) were more likely to wear veils themselves and to think other women should too. These mothers, we argued, also in Evolution and Human Behavior, take this position as it serves their sons over their daughters-in-law.

More recently, Nick Kerry, then busy finishing his PhD at Tulane University, led a study testing our prediction in an online American sample. Participants with more reproductive-age male kin held more conservative positions on gender-related issues like gender roles, women’s rights, and abortion.

Separating sex from identity

The web of conflicting interests that give shape to our social and political attitudes is never easy to trace and there are always multiple factors at play.

Perhaps the most interesting implication of our proposal is it undermines the idea that the interests of women and men sit at fixed odds with one another. Some individuals’ values will align more with the opposite sex than with their own, weakening the importance of gender as a distinct part of social and political identity.


This article is republished, with slight modifications, from The Conversation under a Creative Commons license. Read the original article.


Read the paper: Gendered fitness interests: A method partitioning the effects of family composition on socio-political attitudes and behaviors

An Error of Overperception?

by Jordann L. Brandner, Gary L. Brase, & Jadyn Pohlman


Picture this: you catch the eye of an attractive person across the room, and you go to speak with them. They smile, they laugh at your jokes, and they lean in to listen to your conversation. Would you be able to say if they are sexually interested in you?

Our recent research published in Evolution and Human Behavior asks just that – can men and women reliably tell if someone is sexually interested in them or not? Previous research suggests that men overperceive these situations, often mistaking a woman’s friendliness as cues of sexual interest. Error Management Theory explains this “male overperception” effect as an evolved bias – it is less costly to the man to accidentally overperceive a woman’s interest than it is to miss a mating opportunity.

However, previous research on this overperception have relied on difference scores measures, which oversimplify the situation. In fact, men could have a tendency to respond in a particular way, regardless of it being right or wrong (consistently overperceiving as suggested by Error Management Theory), or alternatively, they could be answering based on how distinct the signals of attraction are from the signals of rejection. In more theoretical terms, evolutionary optimality could be reached by always assuming attraction, but it could also be reached by consistently correct observations, as these correct observations could also avoid the costly error of missing out on someone who was attracted to them.

This possibility was tested using Signal Detection Theory. This theory provides both a measure of bias (how strongly a person prefers to answer “interest” or “disinterest”), and also a measure of sensitivity, which tells how different signals are from non-signals for each person. Moreover, these measures are standardized, allowing comparison across different biases, and are individualized, allowing us to test if mating-relevant personality traits affect sensitivity, bias, both, or neither.

In Study 1, undergraduates were shown written scenarios similar to the one above, then asked if this person was sexually interested in them, how much interest the person had in them, and also answered some personality questions. Study 2 asked online participants similar questions, but using scenarios with much more ambiguous – and even conflicting – behaviors. Importantly, each scenario was pre-judged to determine if it signaled sexual attraction or not by both men and women, and how much attraction was signaled by it. This provided an independent evaluation for comparison.

Contrary to previous research, we actually found underperception of sexual interest – people in our studies had a preference for answering that the person was not interested. Moreover, women were overperceiving interest while men were underperceiving it – completely opposite to what we had predicted. That said, this bias rarely came into play, as participants in both studies were highly accurate at telling if a person was interested in them or not, even with the intentionally confusing behaviors used in Study 2. Traits such as life history strategy, sociosexual orientation, and mate value did not affect participants’ sensitivities or biases.


Contrary to previous research, we actually found underperception of sexual interest – people in our studies had a preference for answering that the person was not interested. Moreover, women were overperceiving interest while men were underperceiving it – completely opposite to what we had predicted.


Interestingly, analyzing these same data with the more typical difference scores measures did not yield the same results. While this analysis did similarly find underperception overall, it also appeared to support an overperception effect for men, despite men’s perceptions being closer to pre-rated interest levels. To understand how such a result could appear imagine people tasked with driving a certain speed, say, 40 miles per hour. Everyone is going slower than that, but men are going 38 mph whereas women are going 35 mph.  Men are going relatively fast (analogous to overperception), but they are actually closer to the target speed.

Men’s difference between the pre-rated levels and their perceptions was smaller, and a smaller difference when negative is a larger number, resulting in the conclusion that men perceived “more” interest than women, when they were simply closer to the truth than women.

Our research combined the powerful and well-established measures from Signal Detection Theory with the evolutionary application from Error Management Theory. The Signal Detection Theory approach incorporating both bias and sensitivity is a better option than the traditional difference score approach. This method reflects the raw data better and allows for more precise, comparable results. It also raises a key question – is overperception simply men and women perceiving different levels of interest, or as we believe, should that term be reserved for perceiving more interest than was originally communicated?

So, to answer our original question, would you know if the person was sexually interested? You, like our participants, would most likely be able to tell. Communication errors still do occur, of course, and further work is needed to better understand the particular types of contexts and people that are more likely to lead to sexual communication errors.



Read the paper: On hits and being hit on: error management theory, signal detection theory, and the male sexual overperception bias

What’s in a leaf? Examining the cues 18-month-olds use to categorize plants

by Stella C. Gerdemann & Annie E. Wertz


Imagine picking and eating wild blueberries in a forest. After finishing with one patch, you walk a little further down the path and see another clump of bushes with blue-colored berries. But these bushes have differently shaped leaves. Do you eat the berries from these new bushes too? This could turn out to be a high stakes decision. The change in leaf shape is relatively subtle, but the fruits on the new bushes might be food or they might be fatal. In an article that recently appeared in Evolution and Human Behavior, we tested whether cognitive mechanisms to correctly categorize plants––and thereby distinguish between potentially safe and dangerous plants––may be present in the first years of life.  To do this, we compared 18-month-olds’ use of leaf shape cues to categorize plants to their use of similar shape cues to categorize human-made artifacts.

Aside from the (hobby) botanist, or the person who might wonder whether they inadvertently bought kale instead of chard, categorizing plants correctly is not a problem many of us frequently face. In most modern environments, humans encounter plants in non-threatening contexts in which the hard work of distinguishing different kinds of plants has already been done for us. For example, we usually don’t need to know precisely what kind of plant we are dealing with in a grocery store to assess its safety. This, however, is not typical of the way plants were encountered throughout most of human evolution. In ancestral environments, humans foraged for plant resources in wild environments and had to correctly distinguish safe plants from dangerous ones to mitigate the costs of toxic plants. In fact, as some of our previous work published in EHB suggests, distinguishing between very similar looking plants is an essential component of social learning strategies for acquiring information about plants.

Another previous study had shown that 18-month-olds can distinguish between different plant types, but that study did not test whether or not infants use different features to categorize plants that they use to categorize other object types, such as artifacts. The previous study also did not address whether infants use cues that may be predictive of the type of plant they are dealing with, like the shape of the plants’ leaves, more than they would use non-predictive cues like pot color to categorize plants. Therefore, in our study, we assessed whether 18-month-olds preferentially rely on leaf shape cues to categorize plants, but not when categorizing artifacts.

To address our research question, we designed closely-matched plant and artifact objects that we presented to infants in our study. The plants were realistic-looking artificial plants with green leaves growing out of brightly-colored pots. The artifacts looked like feather dusters. They were made out of the same leaves as the plants, but instead of being green, the leafy parts of the feather duster artifacts were painted gold and silver and attached to brightly-colored wooden rods. For both types of objects, we pitted leaf shape cues against another visually-salient cue: the color of the pots (for the plants) or the rods (for the artifacts). If leaf shape cues play a special role in the early categorization of plants, then we expected infants to prioritize leaf shape over pot color when categorizing plants in our study. In contrast, we expected that, because these same leaf shape features would likely not be relevant for categorizing artifacts, infants would be less likely to use these cues to categorize our feather duster artifacts.

We tested these predictions by using a category matching task. In this task, we showed half of our 18-month-old infants a target plant and told them its name (“This is a Toma“). Then we showed them two new plants—one that shared the same leaf shape as the target plant, but has a different pot color, and one that shared the same pot color, but had a different leaf shape—and asked infants which one “goes with” the target plant. Infants responded by reaching for one of the two plants. The other half of our infants were given the exact same task using the artifacts.


Infants prioritized leaf shape cues when categorizing plants but did not prioritize those same shape cues when categorizing artifacts.


Our results supported our main hypothesis: infants prioritized leaf shape cues when categorizing plants but did not prioritize those same shape cues when categorizing artifacts. In a follow-up online study, we found that aspects of this categorization strategy persist into adulthood. Adults were less willing to categorize plants by cues other than leaf shape than they were for artifacts.

In sum, our study shows that infants rely on leaf shape cues to categorize plants, but not when categorizing feature-matched artifacts. These findings suggest that distinguishing between plants is indeed an important component of social learning strategies, and leave several open questions. For example, we still do not know whether early experiences influence infants’ emerging ability to use leaf shape cues to categorize plants. Our study did not show any evidence that infants’ early exposure to plants has a measurable influence on infants’ tendency to categorize plants by shared leaf shape cues. Nevertheless, there may be a role of experience that could be better assessed by using more fine-grained methods than the parental questionnaires that we used to measure infants’ experiences with plants. Cross-cultural studies of infants and young children could also shed light on the effects of growing up in environments that afford very different experiences with plants on these early emerging categorization abilities.

Correctly distinguishing between different kinds of plants may no longer be a regular feature of our everyday lives, but the cognitive systems that evolved to solve this problem seem to be very much a part of our modern-day minds.



Read the paper: 18-month-olds use different cues to categorize plants and artifacts

Congratulations to the 2021 HBES Award Winners

The Human Behavior and Evolution Society presents three annual awards to recognize outstanding scholarship and contributions to the field. We are pleased to congratulate the exceptional winners of the 2021 society awards.


Early Career Award for Distinguished Scientific Contribution

This award recognizes excellent young scientists who have made distinguished theoretical and/or empirical contributions to the study of evolution and human behavior.

This year’s Early Career winner is Willem Frankenhuis, Associate Professor, Department of Psychology, Faculty of Social & Behavioural Sciences, Utrecht University, Utrecht. Willem runs the Developmental Evolutionary Ecological Psychology Lab. You can find out more about Willem and his work on his website.

Lifetime Career Award for Distinguished Scientific Contribution

This award is given to HBES members who have made distinguished theoretical or empirical contributions to basic research in evolution and human behavior.

This year’s Lifetime Career winner is Hillard Kaplan, Professor, Economic Science Institute, School of Pharmacy, and The George L. Argyros School of Business at Chapman University. You can learn more about Hillard on his website.


Margo Wilson Award

This award is made by the editors of Evolution and Human Behavior for best paper published in the journal in the previous year.

This year’s winner is one of the first, if not THE first, paper to propose that pathogen elimination activates a coordinated physiological and psychological response and is best characterized as an emotion program. The landscape of basic human emotions has expanded to now include the critical condition of sickness. The paper also received a large amount of media coverage at the time of publication.

Schrock, J. M., Snodgrass, J. J., & Sugiyama, L. S. (2020). Lassitude: The emotion of being sick. Evolution and Human Behavior, 41(1), 44-57.


Our long co-evolutionary history with infectious agents likely began soon after the rise of the first single-celled organisms. This ongoing evolutionary arms race has generated complex host adaptations, many highly conserved, for resisting infection (e.g., innate and acquired immune systems, infection-sensitive developmental programs, sexual reproduction). A large body of evidence suggests that, in humans, pathogen-avoidance disgust is an emotion that motivates avoidance of cues associated with pathogens, thereby reducing infection. However, the question of whether there is an emotion that coordinates resistance to active infection has received less attention. We propose that lassitude is such an emotion. It is triggered by cues of active infection and coordinates the fight against infection by: (a) reducing energetically expensive movement to make more energy available to the immune system, (b) reducing exposure to additional infections and injuries that would compound the immune system’s workload, (c) promoting thermoregulatory behaviors that facilitate immunity, (d) regulating food consumption to be beneficial for the host but detrimental to pathogens, and (e) deploying strategies that elicit caregiving behavior from social allies. Lassitude exhibits the core features of an emotion – it is triggered by cues of an adaptive problem (i.e., infection), generates a characteristic facial expression (e.g., slack facial muscles, drooping eyelids, slightly parted lips), and has distinct qualia (e.g., profound tiredness, reduced appetite, feelings of vulnerability, altered temperature perception, increased pain sensitivity). We outline the information-processing structure of lassitude, review existing evidence, suggest directions for future research, and discuss implications of lassitude for models of human evolution.

A Letter From the Incoming President, Dave Schmitt

HBES is a scholarly community, for many of us it is our academic home away from home. And just like most communities around the world, ours has faced considerable challenges over the past two years. In this message, I want to express my gratitude to those who helped effectively maneuver HBES through unprecedented times, especially Leda Cosmides for her work as HBES president these last two years and Doug Kenrick for his service as past-president of HBES. Thank you also to Bernhard Fink for enhancing the HBES website and improving our capacity for online engagement. Thank you to Nicole Barbaro for her incredible efforts as HBES communications officer, Catherine Salmon for her longstanding contributions as HBES treasurer, and all members of the HBES Executive Committee. HBES has remained strong and resilient because of their efforts in growing our ability to be inclusive, welcoming, and digitally connected.

I also want to express my deep appreciation to the hosts of planned HBES conferences in Detroit and Palm Springs for their flexibility and hard work over the past two years—both conferences are now on schedule for 2022 and 2023, respectively. This was no easy task. Thank you to everyone who helped make our upcoming HBES Virtually Everywhere (#HBES2021) online conference a reality, especially the host committee (Coren Apicella, Chris von Rueden, Nicole Barbaro) and programme committee (Aaron Lukaszewski, Jaimie Krems, Anne Pisor, Cari Goetz). Coren pretty much dropped everything to make HBES Virtually Everywhere happen this summer, we all owe her significant thanks. And kudos to everyone who dedicated themselves to making our HBES Roundtable Seminar Series such a tremendous success this past year (videos of these events may be viewed on YouTube here.

Finally, I want to thank those HBES members who have committed their time and energy for crucially important work on the HBES Grievance Committee and in evaluating HBES grant proposals and award nominations. Jaimie Krems, chair of the HBES Grievance Committee, deserves special thanks for helping to make our community safer and more inclusive these past two years, and thank you to Nicole Barbaro for vigilantly monitoring, analyzing, and reporting on results from our HBES conference climate survey. A key focus of HBES has been on welcoming, developing, and highlighting early-career scholars from across the evolutionary behavioral sciences. HBES has supported graduate student and prospective graduate student luncheons, methods and statistics workshops, and meetings such as Women of HBES. This year at HBES Virtually Everywhere we have an LGBTQ+ mixer event hosted by Michael Barlev (thank you, Michael!).

HBES has honored and rewarded several categories of early-career scholarship at our annual conference, including awards for best conference posters, best post-doc papers/presentations, and new investigator awards. Since 2010, we have honored the best paper published in the HBES-affiliated journal Evolution and Human Behavior with the Margo Wilson Award. We have given HBES awards for Early Career Award for Distinguished Scientific Contribution (2020 Winner, Katherine McAuliffe) and the Lifetime Career Award for Distinguished Scientific Contribution (2020 Winner, David Perrett). Through several of our HBES grant funding mechanisms, we have reached out to support a diverse array of evolution-related undergraduate student meetings, regional academic conferences, and professional organizations around the world.

HBES is truly a worldwide scholarly collaboration, but our community is only as robust and vibrant as the individual HBES members who dedicate themselves to making it so. Thank you to all HBES members whose service to our community has made a difference these past two years and for setting the stage for future generations to make it better still.

Looking forward to the future of HBES, I’m drawn back to the inspiring comments by past-president Dick Alexander during his 2008 keynote address to HBES in Kyoto, Japan. He remarked that, “The most important and frightening of all human adaptations is likely our stubborn and perhaps unique manner of alternating our most intense emotional expressions between the two extremes of amity and enmity within our own species…We need every tool available to understand such things about ourselves. These are reasons why the Human Behavior and Evolution Society has the potential to become the most important scientific organization in the world.”

Every tool available. In my view, that phrase captures the greatest potential of our HBES community. Each year we bring together a wide variety of scholars and their tools from disciplines such as Darwinian literary studies and communications, Darwinian medicine and economics, Darwinian politics and philosophy, evolutionary anthropology and biology, evolutionary neuroscience and genetics, evolutionary psychology and human ethology, evolutionary sociology and family studies, human behavioral ecology and demography, and primatology and comparative psychology (among many, many others). HBES was founded in hopes that we continuously learn from each other, that every HBES conference provides an opportunity for new sparks of connection to be made across disciplines, and that these connections help us to more fully understand the best and the worst of human behavior.

Personally, I’ve found the best part of HBES often comes from attending sessions outside of my area of expertise. The first occasion I encountered the wonderful tool D-Place was at HBES whilst attending a presentation outside my discipline. The stimulating talks I heard and the questions and debates that transpired throughout that session greatly affected my thinking and scholarship for years to come. HBES can do that, should do that, for each of us every year. I’ve found interdisciplinarity and exploring an issue with “every tool available” is where the scholarly magic happens. Further cultivating that interdisciplinary ethos is something I very much look forward to as president of HBES in the next few years.

In these challenging times, our coming together in HBES has never been more important, to science and to our collaborative community. I look forward to seeing you and learning from you all at HBES Virtually Everywhere (#HBES2021). Stay safe.

–Dave Schmitt, President, HBES


Dave will take over duties as HBES President following the HBES 2021 conference, along with the rest of the new members of the Executive Council

There is Nobody Quite Like Grandma

by Ilona Nenko


From an early age, many of us learn that our grandmothers are invaluable in our lives. Their experiences, help, and knowledge can shape us into who we are today, and their influence stretches far beyond simple stereotypes. Grandmothers have long held a special place in almost every culture, and the human story without grandmothers is not much of a story at all. If we look back in time we find that they were even more valuable than they are in the present, with strong empirical evidence that they have helped grandchildren to survive and aided the fertility of their own offspring. These benefits to relatives are thought to have played a role in the evolution of the extended post-reproductive lifespan that separates us from other great apes. In case it isn’t clear by this point, we think grandmothers are very important. But, is every grandmother equally important?

Well, as it turns out, no. Context-dependence is crucial in the expression and outcomes of helping behaviours in other cooperative species, and humans are no different. We have a lot of evidence that maternal grandmothers play a special role in the lives of grandchildren, moreso than paternal grandmothers. It begs the question then, are all grandmother-related grandchild outcomes the same? This is an interesting question because not all grandchildren are born equal. The circumstances of birth can be hugely influential in early life: firstborn children have different outcomes to later births, twins differ in outcomes than singletons, siblings born in a short time frame can suffer negatively compared to those with a longer interval between births, and children born out of wedlock often have worse outcomes than those born within unions. These statuses may seem to be very different at a surface level, but all have a lot in common: higher risk of low birth weight, higher risk of getting lower Apgar scores, higher risk of being born prematurely and – consequently – lower chance of survival. Bad starts are just that – bad – but don’t necessarily spell doom. History is littered with examples of poor starts being overcome. Sometimes all it takes to turn around a tough beginning is a bit of luck. Sometimes it takes a little helping hand.

Here is where grandma returns. Given there are so many bad starts children could face, and given grandmothers are known to provide benefits (at least some of the time), we decided to investigate whether grandmothers increased the chances of survival of children who experienced hard starts to life. We studied Finnish genealogical data from 1730-1895, a time when medical care was very basic and contraception was not available; childhood survival was low, adult life expectancy was much lower than today, and birth rates were high. Grandmothers were very much needed. Finland is an exceptional country for doing this kind of study – Lutheran priests kept extensive records on the population, giving us a rare opportunity to look at ordinary lives in the past, and we know much of how the society operated. We also know from other work with this Finnish population that grandmother presence was not always helpful, particularly if the grandmother was frail. But did grandma help when the going got rough?

The lack of beneficial survival outcomes of grandmother presence for these poor starts reinforces the importance of investigating different contexts of possible help, and perhaps adds another piece to the slowly unraveling mystery of the evolution of extended post-reproductive life.

Alas, in most of the investigated bad starts, grandmother presence was not beneficial. Firstborns, twins, babies born two years after their older siblings, nor illegitimate children –had an increased chance of reaching the age of five if their grandmothers were alive or not. The lack of beneficial survival outcomes of grandmother presence for these poor starts reinforces the importance of investigating different contexts of possible help, and perhaps adds another piece to the slowly unraveling mystery of the evolution of extended post-reproductive life.

It wasn’t all bad news for these historic Finns though: grandmothers were extremely important to children who welcomed a younger sibling before their second birthday, with a massive 41% increase in the probability of surviving to age 5 compared to grandchildren with no grandmother. It isn’t too difficult to see why: the mother had to focus on the fully-dependent, far needier younger child, and it would therefore benefit her and the child if others in the family – chiefly the grandmother – could help. Grandma benefited from this too – by increasing the chances of survival of her daughter’s children, she increases not only the reproductive success of her daughter, but also her own biological fitness. In a way, by caring for her daughter and her grandchildren, she also cares for herself.



Read the paper: Will granny save me? Birth status, survival, and the role of grandmothers in historical Finland

Making Simple Decisions in a Complex Social World

by Pieter van den Berg


We all know humans are social animals. So it makes sense that much of our psychology is geared towards analyzing social situations and choosing appropriate actions for them. This social psychology has to work in a complex and messy world. Every social interaction is different, involving different parties with their own desires and interests, and different possible actions to choose from. To make matters worse, we have to operate under considerable uncertainty: it is often impossible to accurately predict how our actions will turn out.

How has evolution equipped us with an effective psychology to navigate social decision making in this complex and uncertain world? This is not an easy question. Social evolution is intricate, because the fitness consequences of social behaviors depend on what others in the population are doing. A cooperative individual may be successful in a population full of trustworthy interaction partners, but that same individual may fare much worse when surrounded by cheaters. To gain insight in how evolution shapes social behaviors despite these intricacies, scholars have often relied on highly simplified models of social evolution, often reducing the messy social world to just a single type of interaction such as (most famously) the Prisoner’s Dilemma Game. The idea is that if we understand how evolution hypothetically shapes behavior in that very specific situation, we will gain an understanding of how evolution shaped parts of our social psychology.

But does evolution really tailor behavior separately for each specific social circumstance that may arise? This seems unlikely – especially given the fact that individuals often don’t even know all the specifics of the situations they find themselves in. By now, a realization has settled in that the human mind is not a smooth optimization machine, but often works in ways that seem unsophisticated or crude. This is exemplified in what are referred to as ‘cognitive biases’ – proof that people are not consistent or systematically deviate from acting in their own rational interest. Such biases can be the result of a psychological machinery that is not perfectly attuned to the situation at hand, but rather operates by using ‘heuristics’: simple behavioral strategies that work well across a range of situations, but that can ‘misfire’ in some specific circumstances.

Do people apply such rough rules of thumb in social situations, leading to behavior that is suboptimal or inconsistent? A few recent evolutionary modelling studies suggest that we might expect them to. Bear & Rand have shown that evolution can produce a psychology where individuals ‘intuitively’ invest in cooperative relationships, even if that relationship will not extend far enough into the future to make that investment worthwhile. In 2018, I developed a model to investigate how individuals are selected to behave in a ‘messy’ world with many different types of social interactions and some uncertainty about which situation they are in. This model showed that evolution predictably leads to the emergence of simple heuristic strategies that often cooperate, even in situations where it is guaranteed to lead to bad outcomes. These ‘social heuristics’ even evolved when individuals had only intermediate uncertainty about the social interactions they engaged in, and could implement more sophisticated strategies (tailoring behavior to specific circumstances) without any extra cost.

For a new study that was just published in Evolution and Human Behavior, we conducted a decision making experiment in which we confronted participants with a similar situation as the individuals in our evolutionary simulation model. Through software specially designed for this study, our test subjects were repeatedly coupled with other participants to engage in a social interaction. At the core, the social interactions were simple: both participants in a pair had to simultaneously choose whether or not to ‘help’ the other. Helping provided a benefit to the interaction partner (in points that were later converted to real money), but it also had a consequence for the helper herself. This consequences of helping varied between situations: sometimes it was directly beneficial to the helper, but in other situations it carried a crippling cost. Between different experimental treatments, we varied how much uncertainty the participants had about the consequences of helping. This ranged from no uncertainty at all, via partial uncertainty (participants were told that the consequence of helping lied in some range), to complete uncertainty.

The social heuristic our participants were using was effective in turning a situation of uncertainty into a situation of virtual certainty. But, as a side-effect, it also led them to cooperate more.

Our results show that in the treatments with more uncertainty, participants helped their interaction partners more often than if they had little uncertainty. The reason behind this can be found in social heuristics. Most participants were interpreting the uncertainty range they were given in a very simple way: they just acted as if the real consequence of helping was given by the center of the uncertainty range. For example, a participant who was told that the consequence of helping would be anywhere between a cost of 5 and 15 points acted the same way as a participant who was certain that it was 10 points. This is a simple solution to dealing with uncertainty: if you do not know which of many possible scenarios is going to unfold, just choose one that seems typical or likely and act as if you are certain that this is what is going to happen.

The social heuristic our participants were using was effective in turning a situation of uncertainty into a situation of virtual certainty. But, as a side-effect, it also led them to cooperate more. To see why, consider a simplified version in which there are just three possibilities, each equally likely: the cost of helping is either 5, 10 or 15 points. Let’s say you would be willing to help at a cost of 5 of 10 points, but not 15. If you’re like our participants, you will reduce your uncertainty by assuming you are in the most typical situation: you will just act as if you are sure that the cost is 10 points, and so you will help. This means you are helping more than if you would not have had uncertainty, because then you would only have helped in two thirds of the cases. Our experimental results can be explained in a similar way: because participants who had to deal with uncertainty used a heuristic, they ended up helping more than their counterparts that suffered no uncertainty.

So what do these results teach us about the evolution of human social behavior? They confirm that human minds are not calculators aimed at optimizing behavior in every possible scenario that might arise, but that their cognitive solutions have been shaped by a world of considerable complexity and uncertainty. The way our minds deal with this uncertainty is not to painstakingly account for it, but to reduce it to something more manageable with limited losses to inconsistency and suboptimality. Such heuristics can probably play out in many ways, but our experiment shows that they can lead to a higher willingness to cooperate with others.


Read the paper: Uncertainty causes humans to use social heuristics and to cooperate more: An experiment among Belgian university students

Mismatched Sugar High

by Richard Johnson, William Wilson, Sondra Bland & Miguel Lanaspa


How does sugar effect our behavior in modern environments? Here we present the hypothesis that fructose, which is present in added sugars such as table sugar (sucrose) and high fructose corn syrup (HFCS), may have a role in behavioral disorders associated with impulsivity and anxiety. This hypothesis is based on recent research that has found fructose to be distinct from other nutrients in activating a survival pathway that includes foraging for food as one of the behavioral responses. Specifically, fructose is distinct from other foods in that it during its metabolism it can lead to a reduction in intracellular ATP levels. This leads to the degradation of AMP that eventually generates uric acid. The accumulation of uric acid and fall in ATP are associated with a variety of metabolic responses that include the stimulation of hunger and thirst, foraging, the development of insulin resistance, and the production and storage of fat. While this is used by animals in the wild as a survival mechanism to help them store fat in preparation for times when food is unavailable, we posit that the overconsumption of added sugars today is leading to chronic stimulation of these pathways. Foraging, in particular, is associated with risk taking (entering unknown areas), impulsivity and rapid decision making, and even aggression. Here we review the evidence that chronic stimulation of foraging behaviors from consuming fructose might carry increased risk for disorders associated with impulsivity and anxiety, including ADHD and bipolar disorder. We recommend further research to investigate the possibility that fructose ingestion might be a contributory risk factor for these and related disorders.


Watch the video summary of our work, below (shared with permission)


Read the paper: Fructose and uric acid as drivers of a hyperactive foraging response: A clue to behavioral disorders associated with impulsivity or mania?