HBES Evolution of #Punishment Roundtable Seminar Series Event on May 6th

HBES is thrilled to announce the next event in our new Roundtable Seminar Series. On May 6th 2021 at  10:30am -11:45am EST Drs. Nichola Raihani, Max Krasnow, Katherine McAuliffe, & Jillian Jordan,  will engage in discussion, moderated by Dr. Pat Barclay on the topic, “The Evolution of Punishment”. We’re looking forward to engaging with our members on important discussions happening in this area.


As prior events, the live-stream of the event will be hosted on crowdcast and the password to register for the event will be emailed out to HBES members the week of the event (check your spam folder!). The recording of this event, and all prior events, will be made available on our YouTube channel shortly following the event.


If you have any questions about registering for this event, please contact the event coordinators at hbesroundtableseries@gmail.com.


We’re looking forward to seeing you soon!

When is Marriage Harmful to Women?

by David W Lawson

Feature image : A household interview, Mwanza, Tanzania; Credit: David W. Lawson


Over the last decade, my colleagues and I have grappled with the categorization of multiple forms of marriage as definitively costly to women by international development and global health organizations. Chief among these practices are polygynous marriage (sharing a husband with a cowife), ‘child marriage’ (marriage under 18 years), and most recently in our new paper in evolution and human behavior, marriages in which the husband is substantially older than the wife. Each of these phenomena are especially relevant across sub-Saharan Africa where, for example, 40% of girls marry before their 18th birthday.


As an applied anthropologist, I’m immediately wary of ethnocentrism when any practice common in the Global South is categorized as inherently harmful. A widespread tendency to frame these issues through a moralizing lens also raises concern. Plan International’s award winning ‘#stopthewedding’ campaign, for example, presents child marriage as both ‘grotesque’ and demanding of urgent external intervention. Narratives that (over)emphasize the dangers of ‘traditional culture’ can be problematic if they reinforce damaging stereotypes and sideline recognition of broader structural drivers of gender inequality. Anthropologists (and historians) have responded by illustrating the ways in which practices like early marriage may be viewed, not as the product of a morally bankrupt society, but rather rational responses to specific socioeconomic and sociopolitical circumstances.


In this sense, I am also optimistic about the potential contributions of an evolutionary perspective. The polygyny threshold model, for example, suggests that sharing a husband may be beneficial if a man is wealthy enough to provide for multiple wives. A model that receives support in some settings, but not others. And while early marriage has clear potential to be costly (e.g. via elevated risk of early pregnancy), life history theory reminds us that such costs may be tolerated given the benefits of starting a family early when life expectancy is relatively short. Parent-offspring conflict theory may also be useful in understanding why early marriages may be incentivized for parents if not daughters, especially in the context of marriage payments i.e. higher bridewealth or lower dowry for younger brides. Yet, in many cases, early marriage appears driven by female choice (including via elopements against parental will), without clear costs to wellbeing, questioning the notion that women’s agency is restricted. Context is king.


Frankly, without lived experience of societies where such practices are common, let alone the gendered power dynamics of heterosexual marriage and childrearing, I also remain cautious to weigh in on debates about what is good and bad for women. I’ve tried to strike a balance in presenting our research findings as objectively as possible, while being open to rethinking my own assumptions and those of my paradigmatic training. Key here has been a pivot into qualitative methods (spearheaded by Susan Schaffnit), prioritizing the voices of community members deemed at risk, along with collaboration with Tanzanian scholars at the National Institute for Medical Research, especially Mark Urassa, and Joyce Wamoyi.


So, are large spousal age gaps bad for women? Evolutionary psychologists have tended to focus on the mutual benefits of husband-older marriage: with women effectively exchanging youthful fecundity for the wealth and status of senior men. However, even early work in this tradition hints at the limits of this perspective. Kenrick and Keefe for example, report that, while American women find slightly older men attractive at all ages, as men get older they prefer relatively younger and younger women. Such divergent preferences are not mutually compatible.


Surveying Sukuma women living in a rural, but urbanizing community in northern Tanzania, our recent paper provides some potential answers, and raises new questions. Consistent with conflicting preferences, women routinely marry men older than their stated ideals. However, among the large majority married to older men, the age gap did not meaningfully predict self-reported depressive symptomology, autonomy in decision-making (a frequent measure of women’s empowerment), the likelihood of divorce, or reproductive success. While our ability to infer causal relationships is limited with cross-sectional data, these results suggest the magnitude of spousal age differences is of little consequence to women’s wellbeing or fitness – supporting neither a mutual benefits or a sexual conflict model.


Unexpectedly, we also found that marriage to a younger man, a rare arrangement in this community, was associated with relatively poor wellbeing for women. Qualitative findings indicate that such husband-younger marriages are socially shameful; suggesting costs of norm violation along with selection of relatively disadvantaged individuals into atypical marriages. This could come about, for example, if men with otherwise limited marriage prospects partner with older women who themselves are relatively disadvantaged prior to marriage.


These results correspond to our wider findings on polygyny and child marriage, both of which show little evidence of being directly costly to women’s wellbeing, more obviously predicted by factors like access to education and health services. In fact, in past studies we have shown that marrying polygynously is associated with relatively superior child health and food security compared to monogamous marriage; and brides under the age of 18 years report greater decision-making autonomy and community respect than their unmarried peers. As illustrated above, our results also confirm the role of social norms and norm violation in defining feasible options for girls and women. Related research shows that gender norms favoring male authority are represented and reinforced via Sukuma songs about marriage.


On the one hand, knowing that certain marriage practices do not predict poor wellbeing when girls and women are contrasted within a community usefully steers us away from simplistic interventions that might punish the families involved. We have argued, for example, that criminalizing marriage under 18 years may be damaging for female adolescents by limiting options, unless such interventions are also effectively combined with policies addressing the vulnerabilities experienced by those delaying marriage, i.e. exposure to risky sexual behavior, premarital childbearing, and negative social judgements of unmarried women.


Our research cautions against portraying ‘traditional’ marriage practices as the lynchpin, that once unlodged will dismantle patriarchy. But leaves open the possibility that community-wide changes in these practices may nevertheless have positive impacts for women by disrupting wider social norms.


On the other hand, it would be erroneous to imply that our results imply marriage arrangements such as large spousal age gaps are harmless. Critical here is the realization that a girl or woman may opt for a certain marital arrangement as the best available alternative, but the fact that her option set is remarkably limited by wider cultural norms can itself be considered an indirect act of coercion. These instances, perhaps best considered forms of ‘structural violence’, are less often considered within adaptationist frameworks that certainly model sexual conflict, but more often via theorizing about opposing individual optima and emergent strategies, rather than tackling more systemic forms of oppression. The challenge ahead is to disentangle to what extent specific marriage practices are best understood as the product of patriarchal regimes, or themselves a root cause of gender inequality.


Our research cautions against portraying ‘traditional’ marriage practices as the lynchpin, that once unlodged will dismantle patriarchy. But leaves open the possibility that community-wide changes in these practices may nevertheless have positive impacts for women by disrupting wider social norms. We need more social scientists, including evolutionary-minded scholars, with their keen adherence to the importance of context and variation, to apply themselves to these tricky questions. Fundamentally, the question is not if, but when and where, polygyny, early marriage and large spousal age gaps can be harmful to women. We also need to be mindful to make sure that investigation into these sensitive topics is fully inclusive of researchers and communities in the Global South. Above all, as argued recently by Akurugu and colleagues Gender activism needs to be sensitive to contextual norms and respectful of the ‘oppressed’ subjects of ‘liberation”


Read the paper: Lawson DW, Schaffnit SB, Hassan A, & Urassa M. (2021). Shared interests or sexual conflict? Spousal age gap, women’s wellbeing and fertility in rural Tanzania. Evolution and Human Behavior. 42: 165-175

Does the Nose Know? Exploring the links between smell, disgust, and mating strategies

by Marjorie Prokosch, Zachary Airington, and Damian Murray



Our sense of smell helps us to make sense of the world. Our mornings can be improved by smelling a cup of coffee; our nose tells us which foods in the fridge may have turned; the smell of a loved one’s worn shirt transports us to the emotions of that relationship. However, despite how daily experiences are influenced by smell, relatively little research has examined how smell guides human social cognition and behavior.

Previous research points to two social processes in which our sense of smell is especially important: 1) deciding with whom we should form and maintain close relationships, and 2) helping us to avoid things and people that could make us sick. People rate smell as being an important factor in romantic partner choice, and tend to find the smells of a romantic partner to be more comforting and attractive than the scents of others. People also tend to be disgusted by and avoid the sources of foul, disease-connoting odors (like the body odors of sick people). New research is now beginning to examine how individual differences in how well we smell might also shape these processes.

In a recent study, we explored how smelling ability, disease avoidance, and one aspect of close relationships—mating strategy—are related. Here, by mating strategy we refer to people’s interest and participation in monogamous romantic relationships (long-term mating strategy) and short-term sexual relationships (short-term mating strategy). We predicted that smell ability would relate to people’s trait disease avoidance and mating strategies. For example, people who can more easily detect smell-related disease threats might tend to be more disease avoidant. Further, people with greater ability to smell relevant cues of quality or compatibility in potential partners (or, proximally, who might be more easily disgusted by unfamiliar body odors) might be less inclined to engage in short-term sexual relationships. Past research has also found that people high in disease– and sex– related disgust are less inclined to engage in short-term sexual relationships, so we expected to find a similar link in our study, too.

To measure smell ability, we tested participants with Sniffin’ Sticks—a battery commonly used in clinical smell research.  The Sniffin’ Sticks test measures three facets of smell ability: threshold, discrimination, and identification.

Threshold is the ability to detect scents. Participants smelled groups of pens where two were unscented and one contained a concentration of n-butanol, which has an alcohol-like smell. Participants with a more sensitive smell threshold could correctly pick out weaker concentrations of n-butanol. Discrimination is the ability to tell scents apart from one another. Participants smelled groups of pens where two pens contained one scent and a third pen contained a different scent. Participants who were more discriminating correctly picked out more of the uniquely scented pens across trials. Identification measures the ability to recognize and name specific odors. Participants smelled a set of common scents (e.g., leather, fish, banana). Participants with greater identification ability could correctly name more of those scents. In total, the test takes about 45 minutes to administer.  Participants then completed surveys assessing their interest in short and long-term mating strategies, their dispositional sexual and disease-related disgust, and how chronically vulnerable to diseases they felt.

We found that smell discrimination–people’s ability to tell smells apart from one another—was related to people’s interest in short-term mating, such that people who were better at telling smells apart tended to report less comfort with engaging in short-term, sexual relationships.  People with greater smell discrimination also tended to report more disgust towards potentially unpleasant sexual scenarios (such as hearing others have sex). These relationships remained consistent after accounting for other factors that could meaningfully impact performance such as gender, English proficiency, and recent sickness (and after adjusting our false positive rate to account for performing multiple tests).


We found that smell discrimination–people’s ability to tell smells apart from one another—was related to people’s interest in short-term mating, such that people who were better at telling smells apart tended to report less comfort with engaging in short-term, sexual relationships.


Interestingly, we did not find a link between people’s smell discrimination abilities and their disease avoidance tendencies (disgust towards the germ-rich situations, feelings of vulnerability). Superficially, this is inconsistent with past theorizing about smell ability and disease avoidance. Smell threshold and identification abilities did not consistently relate to any of our survey measures. Why might this be the case? It is possible that there are really no relationships of interest between threshold, identification, and mating or disease avoidance. However, it’s also possible that aspects of our testing procedure, like the scents or survey measures we used, interfered with our ability to detect small but meaningful relationships.

Our results leave lingering questions for future work. Why is the ability to tell different scents apart relevant to discomfort with short-term mating situations and strategies? It’s possible that when evaluating potential partners, the ability to discriminate between different scent cues of “good partner fit” is more important than the ability to detect these cues, per se.  People especially sensitive to different scent cue combinations that signal “bad partner fit” might in turn, have a dampened desire to pursue mating strategies that emphasize casual sex. We also do not know which specific scent cues might be important for determining “good” or “bad” partner fit. Scents related to health, immune compatibility, or fertility may be worth investigating.

Another question is whether (or how) specific smelling abilities actually factor into established, long-term relationships. Although our data didn’t imply that smell sensitivity influenced actual relationship status, smell ability may still be important for forming and maintaining long-term, romantic partnerships. For example, some research does suggest that smell is related to sexual satisfaction. Specific smell abilities may play a role in aspects of long-term mating strategies that we didn’t measure in our study.

In sum, does the nose know? Our research suggests, maybe. At least, our ability to detect differences in odor cues seems to be related to our comfort with short-term mating.


Read the paper: Investigating the relationship between olfactory acuity, disgust, and mating strategies

Interview with 2020 HBES Lifetime Career Award Winner David Perrett by Carlota Batres


David Perrett is a professor at the University of St Andrews and the winner of the 2020 Lifetime Career Award for Distinguished Scientific Contribution, which he will receive at the next HBES conference. Carlota Batres, an assistant professor at Franklin and Marshall College and one of Dave’s former PhD students, interviewed him for HBES.



Carlota: Can you tell us how your academic journey started?

Dave: As a kid I grew up in the country in a house between two sloping fields. A small stream ran through the garden and churned up stones full of fossils (shells and trilobites) which I found captivating. My brother pitched a disused aeroplane nose cone (somehow acquired by my father) over the stream so I could sit inside and study life in the mud (e.g., bloodworms and what ate them). This gave me a head start in thinking about evolution and ecology (though those words were not in my head). In my teens, I had inspirational biology and chemistry teachers and took to being a swot.



Carlota: Out of your 300+ publications, which project has been the most fun for you and why?

Dave: Transforming faces lets you to poke fun at villains, politicians and friends, all in the name of science. A newspaper cheered us with the heading “Boffins help Thatcher’s image fade away” when we morphed the prime minister to a challenger.


Carlota: Rumor has it you are retiring. Is this true? If so, what will you miss the most and what are you most looking forward to?

Dave: I am now on a 20% contract but still work most days. I already miss the privilege of planning experiments and analysing experimental data with smart researchers. Exploring data hot off the press is like opening a present, you might guess at what’s going to be inside but the reality of what you find is always more interesting. The young brains that came through the lab invariably brought humour and curiosity, making the work environment happy and stimulating. I tried to keep in mind that the process of science should be enjoyable and is more important than any result. Our lab was open plan which meant I could drift from one colleague to another and disturb all; the proximity and atmosphere kept us all on our toes.

I now look forward to leisurely breakfasts watching garden visitors (predominantly birds). They come each with their own schedule and tricks: squabbling greenfinches, blackcap bullies and feisty robins.


Carlota: You change your hair color often, and many times have several different colors at once (e.g., purple, green, blue). Is there a method to when and what colors you dye your hair?

Dave: There several drivers of colour use. At northern latitudes you need something to cheer you through the long grey months. The coloured appearance of my wife, Anne, and myself also helped mutual recognition (I am fairly face blind). Initially a change in colour would justify new additions to our wardrobe.

The academic system embraces eccentricity so I treated appearance as a kind of handicap; if people took me seriously despite how I looked then what I was doing must be OK. It is a mark of independence or stupidity, or both. I have encountered disapproval only 2 or 3 times (e.g., looking for a place to stay in Niagara Falls, a door was closed in my face). I think people are often amused, so if our eyes meet there is a positive expression to react to.


Carlota: Can you tell us about your unique exercise and eating routines?

Dave: Hmm! An earlier me loved to run most days and explore wherever I was (i.e. get vaguely or actually lost). The best times were running at Pete Henzi and Louise Barrett’s study site in the Karoo semi desert among giraffes and antelope, hoping that 4 of the big 5 would take no notice of me. Running kept me warm at -24°C, when snow lined my eyebrows and an icicle hung from my nose, and running cooled me while lapping small sweaty tropical islands.

I rationalised that the exercise needed fuel so took to eating 4-5 meals a day. Vinet Coetzee taught me about 2nd breakfast during her PhD in the lab. Since then I have disgusted/amused staff in the coffee room eating lentils or cold beans topped with chilli as the perfect mid-morning pick-me-up. Now diet is just entertainment as I eat similarly but have had to stop running through injury.


Carlota: What is something people at HBES would be unlikely to know about you?

Dave: I failed English Language O Level and have been so lucky to have had Anne using her talent and training to check every work word I’ve put my name to. We enjoy flowers and have a garden with special places for poppies (every type from the blousy Shirley to the sacred Himalayan blue). Creepy crawlies are just as important to us, so we use a UV night light to attract moths in our garden and go on fungal forays turning up oddities like a red club fungus that eats insects.

HBES 2021 Election Results

#HBES2021 Virtually Everywhere | Official Announcement

We are thrilled to announce that the annual meeting of HBES is going virtual this summer! Between June 24th and July 2nd, we will bring you an action-packed program, featuring the following (confirmed) speakers:


Keynote Address
Richard Wrangham (Harvard University)


Plenary Addresses
Michael Bang Petersen (Aarhaus University)
Magdalena Hurtado (Arizona State University)
Michael Muthukrishna (University College London)
Annie Wertz (Max Planck Institute for Human Development)
Melissa Wilson (Arizona State University)


Abstract submission will open April 1st for organized symposia, and April 16th for individual talks, blitzes, and posters. Submissions will close on April 23rd, and acceptance decisions will be sent out by May 7th.


–To avoid burnout, the conference days will be shorter than usual and spread across more days. Meeting times will shift from day to day, in order to accommodate as many international time zones as possible.
–Even if you already submitted an abstract for the in-person conference in Palm Springs, you still need to submit (again) for the virtual meeting. We are a separate host and program committee.
–HBES members will enjoy FREE registration. Not an HBES member? Join or renew today!


Stay tuned for updates about the schedule and program. We look forward to seeing you in (virtually everywhere)!


The Program Committee: Aaron Lukaszewski, Jaimie Krems, Anne Pisor, Cari Goetz
The Host Committee: Coren Apicella, Chris von Rueden, Nicole Barbaro

HBES #Teaching & Cumulative Culture Roundtable Seminar Series Event on March 25th

HBES is thrilled to announce the next event in our new Roundtable Seminar Series. On March 25th 2021 at 11:00am -12:15pm EST Drs. Michelle Sugiyama, Maxime Derex, Cristine Legare & Sheina Lew-Levy,  will engage in discussion, moderated by Kevin Laland on the topic, “Teaching and Cumulative Culture”. We’re looking forward to engaging with our members on important discussions happening in this area.


As prior events, the live-stream of the event will be hosted on crowdcast and the password to register for the event will be emailed out to HBES members the week of the event (check your spam folder!). The recording of this event, and all prior events, will be made available on our YouTube channel shortly following the event.


If you have any questions about registering for this event, please contact the event coordinators at hbesroundtableseries@gmail.com.


We’re looking forward to seeing you soon!

The Height of Entitlement: Are Taller People More Opposed to Wealth Redistribution?

by Thomas Richardson


Men are taller, bigger, stronger and more warlike than women. Or to use the academic term; men are the formidable sex. This is true across the vast majority of human cultures and time periods. In the last 2 decades many studies have investigated how we got like this, and how it affects our minds and behaviours today.

Formidable men in our ancestral environments would have likely got what they wanted more than less formidable men. They could simply threaten anyone who attempted to stop them getting their way. Others may have also wanted to appease these men, as they make powerful allies. One theory goes that this would lead to men evolving to calibrate their demands to their formidability. Big and tough? Demand more. Small and weedy? Maybe keep your demands close to your underdeveloped chest.

How would this play out in our modern societies? One prediction is that formidable men might prefer a society that was less equal, for example by opposition to government redistribution of wealth. Many people are happy with inequality if they’re the ones on top, and in ancestral societies, formidable men would have often been up there. On the other hand, some researchers argued that this trend might reverse if the big bloke was poor. Then they might forcefully argue for equality and wealth redistribution, as it would benefit them. Put simply: more formidable men should argue more for their own interests.

This theory might resonate with you. Most of us know a big, strong, entitled jerk in our own lives. But if you’re a bit sceptical of this theory, you’re not alone; I was too when I first read the research. But there seemed to be quite a few studies showing that more muscular men were averse to equality and government wealth redistribution. Some studies found it depended on their own wealth. The studies had cross-cultural samples, some quite large. None of that means the research should be uncritically trusted, but these are generally good signs. So, I was intrigued, and thought I’d do some work on it myself.

One thing previous studies hadn’t tested as much was whether the theory applies to the other indicators of formidability: height. The theories described above would predict that taller men would be less supportive of equality. It might also predict that this relationship would depend on wealth: tall, poor men would support equality, as it would be in their best interest, whereas tall, rich men would oppose it.

In my paper, I set out to test whether these hypotheses applied to height as well as muscularity. To do this I used data from the European Social Survey. This survey collects data on attitudes and behaviours (mainly relating to politics) for ~2000 people representatively sampled from each European Country. They’ve done this every 2 years with only slight modifications to the questions, going all the way back to 2002! Luckily, in wave 7 they obtained data on respondent’s height, giving me free, easy access to a rich dataset of 27,000 representatively sampled people. It really is a fantastic resource, and I advise researchers to check it out. Datasets like these are underutilised by evolutionary social scientists, and have a lot of potential. Because while these datasets have been bled dry by political scientists and economists, these researchers lack the evolutionary perspective, and so there are many hypotheses they wouldn’t think to investigate. Plus, in the midst of a global pandemic, where else are we going to get data?

One of the difficulties with this type of research is establishing causation. A correlation between muscle mass and political attitudes doesn’t tell us whether the muscle mass causes us to have the attitudes or having certain attitudes cause us to develop our muscles. Studying height partially gets around this, because men can’t really change their height. As such, the causation between formidability and attitudes can only go one way.

But this still leaves the problem of third variables: perhaps something causes some men to be taller/stronger and also causes them to hold more self-serving attitudes. A related issue was alternative mediators: perhaps height does affect attitudes towards wealth redistribution, but it’s not caused by increased self-interest. It might just be because taller people are more educated or because they’re older. To make my case I’d have to control for these third variables and alternative mediators to make any proper conclusions. Getting at causality with observational data can be done but is certainly a challenge! In this study, I controlled for age, income, years of education, conservatism and whether someone had a position of authority at work.

The evidence supported both hypotheses about equally:

  1. Overall, taller people endorsed anti-redistribution attitudes more than shorter people.
  2. But the effect of height also depended on wealth. Among richer people the trend held, but among poorer people the trend reversed. For poorer people, being taller meant more support for government redistribution of wealth. We could put this interaction effect another way: though richer people supported redistribution less, the being tall made the effect even stronger.

Notice how I’ve written ‘people’ not ‘men’. One result that was confusing, and not fully consistent with the theory, was that women showed the effects as strong as men did. Most women aren’t in the same ballpark as men when it comes to formidability, and historically haven’t engaged in large amounts of violent competition compared to men. So we wouldn’t expect to see the same effects in women. But I did. I list some possible reasons in the paper, but ultimately I can’t explain this result. Sometimes as a scientist you have to raise your hands and admit you don’t know.

With the main results established, I ran as many robustness checks as I could think of to see how strong the result was. There are often many ways to use statistics to test a particular hypothesis, and there isn’t always a clear right answer. Rather than choosing (and perhaps risking bias), one option is to run them all and see whether a hypothesis is supported most of the time. So that’s what I did, and the results held pretty well, increasing my confidence in the result.

One thing to note though is that the effects I found were very small. Small effects can matter, and small effects on the political attitudes of a whole country may result in a lot of votes. Also, some argue that most effects we can expect to see in behavioural science are small. But how small is too small? I don’t really know. A question that has seen a lot of discussion in recent years is how we define a ‘smallest effect size of interest’, where any effect smaller than this may as well be 0. Working out the smallest effect size of interest for hypotheses in the evolutionary social sciences will likely require refining our theories a lot more than many of us currently do, to the point where they make concrete predictions about effects we’d expect to find in our studies. This sounds hard, and it is, but will certainly be worth it.

So to sum up: In a large, representative sample of Europeans, I find that taller people are less supportive of government redistribution of wealth, especially if they are also wealth themselves. If you want to learn more, give the paper a read, and take a look at the data and R script if you’re curious about the details of the analyses. If you have any questions or comments, I’d love to hear them!



Read the paper: Height is associated with more self-serving beliefs about wealth redistribution


Interview with 2020 Early Career Award Winner, Dr. Katie McAuliffe

Dr. Katie McAuliffe, Assistant Professor in the Department of Psychology at Boston College, was recently awarded the 2020 HBES Early Career Award for her distinguished contributions to the field of evolution and human behavior. To learn more about Katie, her postdoctoral scholar, Dr. Dorsa Amir, interviewed her for HBES.


Dorsa: Academia can sometimes take us down winding paths we couldn’t have seen in advance. Can you tell us a little about the academic journey that led to being a professor of psychology at Boston College?

Katie: Winding path is right! I actually started out interested in cetacean research, briefly toyed with the idea of going to graduate school to study postcolonial literature, applied to Richard Wrangham’s lab to study chimpanzees (sidenote: I never studied chimpanzees) and ended up studying fairness—or lack thereof—across a bunch of animal species before landing on humans. So, I came to psychology through evolutionary biology and anthropology which I think shows that many winding paths can lead to interesting work on human behavior.


Dorsa: I’ve heard rumors that you may or may not include Easter eggs in some of your publications. Can you confirm or deny?   

Katie: This is true, but I cannot comment further.

Dorsa: I’m often impressed (and vicariously overwhelmed) by the number of different projects you’re able to successfully juggle at once. What strategies do you use to keep them all organized and balanced?

Katie: Are they all organized and balanced? That’s my first question. But assuming it’s true, one thing that helps is to have projects at different stages; that naturally keeps them organized. More importantly, it helps to have projects that are led by excellent postdocs and graduate students working as a team. My guiding principle has been to build a good team first, and good things grow out of that. I also use a number of apps and platforms to help organize our research. Our lab uses Basecamp to coordinate and communicate, which helps with organization, and I personally use Trello, which is a tool that visualizes projects and deadlines. I am also religious about “strategic planning”, in which I set my goals for the semester and break them down into actionable steps that I fit into my calendar.

Dorsa: I knew I was in Katie McAuliffe’s lab when I first opened up a cabinet and found it absolutely filled with candy. Have you considered contacting Skittles® for a sponsorship?

Katie: Actually, yes. I have contacted them at least once, if not twice, even having gone through a conflict-of-interest phone call. Sadly, they never wrote back.

Dorsa: You’ve done a lot of fieldwork in your career studying both humans and non-humans. Is there a field experience that stands out as particularly memorable?

Katie: My year of fieldwork studying meerkats in the Kalahari was magical. The people there were incredible, and the work itself was fascinating. The meerkat system is great because you can actually see the meerkats. Cetaceans, on the other hand, are harder to see since they’re mostly underwater. Sometimes in studying animal cognition, you’re looking for things that aren’t obvious — like, does this animal have this psychological capacity? And you design experiments around that. But with meerkats, our study was built around a naturalistic and easy-to-observe behavior: teaching. We designed experiments that celebrated their natural behavior, and that made it really exciting. Also, the Kalahari is just beautiful: it’s a gorgeous landscape, you’re out there by yourself, and you’re constantly surrounded by all these different animals living and moving all around you. In addition to the Kalahari I also loved doing fieldwork with kids in Western Uganda. My first trip to Uganda to collaborate with the Kasiisi Project totally reignited my love of developmental psychology.

Dorsa: Katie, you’re a fan of puns. If someone wrote a biography about you, what would the title be? 

Katie: Fairness and “Pun”ishment.

Dorsa: How do you stay engaged and excited about projects that can take years to come to fruition as a finished publication?

Katie: It comes back to the team part; I really enjoy working with the people I am working with. And as cheesy as it may be, for me, it’s more about the journey than the destination. I actually like the day-to-day work, so even if a project takes years, it doesn’t really matter to me.

Dorsa: I happen to know you’re particularly fond of label makers. What is the most unnecessary item you’ve labeled?

Katie: Actually, I’d argue that none of my labeling is unnecessary. For instance, I’ve labeled every section of my refrigerator. How else would everyone know where the ketchup goes?



You can learn more about Katie by visiting her website


Why Do We Punish? Proximate Motivations Reveal the Evolutionary Functions of Punishment

by Paul Deutchman


Imagine that you are at an academic conference with a friend. As you walk into the convention hall one morning, you see a table covered in Danish pastries. You grab a couple pastries and put them on a plate. Before you can even take a bite, you remember that you left your poster in your hotel room upstairs. The poster session is about to start so you leave your pastries with your friend and run to your room. When you come back down, you see that your friend has eaten one of your pastries. You would probably be less than thrilled with their friend, maybe even a bit disgruntled. Now imagine a slightly different version of that scenario. This time, before you can grab any pastries you realize you forgot your poster and run upstairs to get it, but not before asking your friend to grab a few for you. When you come back to the convention hall, you see that your friend has a plate full of Danishes for herself, but only grabbed one for you. This might also make you kind of mad, right? However, it is less clear why that is the case in this scenario; your friend didn’t steal your pastries, but it still feels like they did something wrong.

This example captures two of the main, proximate motivators of punishment: revenge, the desire to reciprocate harm, and inequity aversion, the dislike of unfairness. What the latter example highlights, is that unfairness alone can be upsetting enough to motivate punishment. Understanding the motivations behind punishment is an important topic because understanding what motivates punishment can inform our understanding of the functions of punishment and why it evolved in the first place. Revenge-based punishment serves an important deterrence function by discouraging those that harm us from doing so again in the future. On the other hand, inequity-based punishment may serve an important leveling function by ensuring that we’re not worse off than others and potentially giving us a competitive edge, or at least preventing others from gaining too much of a competitive advantage.

Previous research on the relative importance of inequity aversion and revenge has been mixed – some work has found that punishment is motivated primarily by revenge, while other work has found that it is motivated primarily by inequity aversion. Recent work has added more nuance to this debate, finding that punishment is mainly motivated by revenge, with inequity aversion only factoring in as a secondary motivation when people experience losses. However, it remains unclear whether inequity aversion matters in the absence of losses. In other words, do people ever punish others simply because of unfair outcomes?

In our study, we addressed this question by pairing up two people who have never met and having them play an online economic game for real money. The game had two conditions, a Take condition and an Augment condition. In the Take condition, as in the pastry example, one player could steal money from the participant or do nothing. In the Augment condition, one player could give money to the participant at no cost to themselves or do nothing. By examining cases where a player chose to not give this money to the other player, this condition allowed us to investigate whether inequity aversion motivates punishment in the absence loss. Specifically, because the participant was not harmed by the other player in this condition, the only motivation for punishment is to reduce inequity.

Importantly, we also varied the level of inequity participants experienced by manipulating the starting endowments they received at the start of the task: some participants had more (advantageous inequity), the same amount (equality), or less than the other player (disadvantageous inequity). This resulted in participants experiencing different degrees of inequity, which was either worsened, improved, or unchanged depending on whether their partner decided to steal (Take condition), give (Augment condition), or do nothing, respectively. After learning about the other players decision and seeing their relative endowments, participants could punish by paying a cost to reduce the other player’s earnings.

In support of past work, we found that people mainly engaged in punishment when the other player stole from them, suggesting that punishment was motivated primarily by revenge. However, unlike previous work, we also found that, regardless of whether the other player stole from them, participants were more likely to punish when they had less money than the other player as compared to when they had the same amount or more. This finding—that people punished when they experienced inequity but not losses—offers evidence in line with the idea that punishment is motivated by fairness concerns.

Furthermore, our data provide some support for the theory that punishment serves a competitive function by increasing relative payoffs and status. Because punishment in our study used a 1:3 fee-to-fine ratio (i.e., the ratio of punishment’s cost to damage), it is difficult to disentangle any punishment from a competitive motivation to increase relative payoffs. Additionally, a small minority (5-10%) of participants in our study punished the other player for choosing the prosocial option (not stealing or augmenting), even when they had equal or slightly larger endowments. Together, these results potentially suggest that some participants were motivated to punish antisocially, perhaps out of spite or a competitive motivation.

Findings from our new study are exciting because they offer strong evidence that there are different motivations for punishment. That punishment is motivated by both revenge and inequity aversion suggests that punishment likely evolved for multiple functions—both a deterrence function and a fitness-leveling function. That punishment can serve both functions highlights how evolution can design one behavior to serve different goals.

Future work should examine cultural differences in the motivations underlying punishment. We know there are meaningful differences in punishment across societies, and it will be important to explore the prevalence of revenge and inequity aversion motivations in these countries. For example, inequity aversion might motivate punishment more in societies that lack strong formal enforcement mechanisms and where there is more intense local competition for resources, environments where fitness-leveling might be an especially adaptive strategy.

In sum, our work suggests that punishment is motivated by different factors—people are primarily motivated by the desire to seek revenge, but also to some extent by the desire to reduce inequity. These findings underscore the multifaceted functions punishment evolved to serve and highlight the need for greater research on punishment across different societies, especially in non-WEIRD societies.


Read the paper: Punishment is strongly motivated by revenge and weakly motivated by inequity aversion