The Kindness of Strangers:

How a Selfish Ape Invented a New Moral Code​

In their efforts to explain humans’ generosity toward strangers in the modern world, scientists often appeal to evolutionary models of cooperation based on relatedness and reciprocity: They argue that our evolved instincts for cooperation produce prosocial behavior today through so-called misfiring. However, natural selection has idiot-proofed our cooperative instincts by furnishing them with identity-verification procedures and fail-safes that limit misfiring. There is another evolutionary explanation for human generosity, however: It rests on the idea that it has been our instincts for finding and tracking our incentives, along with our instincts for reasoning and argumentation--sharpened through repeated encounters with mass suffering--that created our history of helping strangers. Because of these repeated collisions with mass suffering, coupled with advances in ethics, we want to help. Because of advances in trade, technology, and science, we can.

The Real-Making of Gods and Spirits

Why does religion persist? I argue that the standard approach in the Cognitive Science of Religion explains only one part of the story. Gods and spirits need to be made real for people, and the real-making, I argue, becomes an end in itself. In this talk, I lay out the ways in which the sense of supernatural presence is kindled for people, the challenges to this view, and the consequences if my view is correct.

Charles Darwin meets Dale Carnegie

I’ll discuss an upcoming book with David Lundberg-Kenrick, which applies ideas and findings from evolutionary psychology to the question: How can we live fulfilling lives in the modern world, given the constraints imposed by powerful ancestral motives? A quick overview of the book’s ideas: Evolutionary psychologists, working at the interface of anthropology, biology, psychology, and economics, have traditionally been interested in purely scientific goals: to understand links between Homo sapiens and other animals, for example, or to compare people living in cultures from the Brazilian jungle to outer Mongolia. Along the way, the basic science has, almost serendipitously, uncovered precious nuggets of practical wisdom. Those nuggets are scattered about, often hidden in obscure scientific articles. But much of that emerging wisdom can be organized into a simple and easy-to-visualize scheme—a 7-step pyramid of fundamental human motives. Climbing that pyramid should be easier in the modern world than it was for our ancestors, who had to struggle by without richly stocked supermarkets, antibiotics, indoor plumbing, and portable electronic devices that can download a map if we’re lost. But those perennial problems are, in some ways, more difficult to solve today. For one thing, the default solutions—psychological reactions that helped our ancestors survive in the ancient world—aren’t always well matched to our modern circumstances. For another, the very strength of our ancestral desires opens us up to a new set of technological parasites in the modern world.

Behavioral Endocrinology for (Evolutionary) Social Scientists: Promise and Pitfalls

The study of hormone-behavior interactions has a long scientific history, but the advent of social psychologists and anthropologists leveraging hormonal measurement to get ‘under the skin’ of their primate subjects is a relatively recent development. There are numerous advantages to such an approach, many of which stem from a rich theoretical base developed in adjacent disciplines, but others are more pragmatic. In particular, hormonal measurement is often non-invasive and fairly affordable, thus posing a low barrier to entry. While social scientists, particularly of the evolutionary variety, have adopted many of the goals of behavioral endocrinology, the typical methods used and inferences drawn differ from classic behavioral endocrine approaches. Some of these differences reflect necessary and/or defensible gambits. Others, however, suggest misunderstandings or oversimplifications of the biological systems in question. In this talk, I identify some recurrent pitfalls—many of which I only know from running straight into them. I also sketch the outline of a ‘how-to guide’, or maybe just a set of reminders, for behavioral scientists interested in contributing to a common groundwork for explanation across disciplines.

Our Grandmothers’ Legacy:

Challenges Faced by Female Ancestors Leave Traces in Modern Women’s Same‐Sex Relationships

Across history, female peers were women’s primary romantic rivals in competing to attract and retain investment from mates. Modern women show signs of this competition, disliking and aggressing against those who threaten their romantic prospects, targeting especially physically attractive and sexually uninhibited peers. However, women also rely on one another for aid, information, and support. As most social groups were patrilocal across history, upon marriage, women left their families to reside with their husbands. Female ancestors likely used reciprocal altruism or mutualism to facilitate cooperative relationships with nearby unrelated women. To sustain these mutually beneficial cooperative exchange relationships, women may avoid competitive and status-striving peers, instead preferring kind, humble, and loyal allies. Ancestral women who managed to compete for romantic partners while simultaneously forming cooperative female friendships would have been especially successful. Natural selection may have therefore favored strategies to achieve both competitive and cooperative goals, such as guising one’s intrasexual competition as prosociality or vulnerability. These historical challenges make sense of the seemingly paradoxical pattern of female aversion to competition, relational aggression, and valuation of loyal friends, offering insight into possible opportunities for intervention.

The Evolutionary Origins of the Sense of Fairness

Do other animals, and especially our closest living relatives, chimpanzees, care about what’s fair and what’s not? I will present a series of studies suggesting that they don’t. The key psychological mechanism underlying human fairness - social comparison - does not modulate chimpanzees’ reactions to various distributions of resources. However, I will also argue and present data indicating that chimpanzees form complex interpersonal expectations that constitute important evolutionary precursors to fairness expectations in humans.

Finding the Femina Economica

I propose that women are not less competitive than men, but express it differently, through adaptations that evolved in conjunction with a tradeoff between motivations to overtly compete for resources, stay alive and invest into offspring, attract and retain mates, and not alienate potential allomaternal allies. To test this hypothesis, we designed a first series of experiments using, as treatment, different types of prizes (N=1,229 from Togo, Sierra Leone, Bosnia, Colombia, and China). Once the incentives were switched from cash to child-benefitting or gender-stereotypical goods, the gender gap in competitiveness was largely eliminated, whereas gender-neutral placebo prizes had no effect (Cassar, Wordofa & Zhang, 2016; Cassar & Zhang, 2021). A second series of experiments implemented a tournament treatment in which winners had the opportunity to share their prizes with losers in addition to winner-take-all tournaments. In a study (N=438 from MTurk), an initial 26% gender gap in performance vanished with the inclusion of the sharing option (Cassar & Rigdon 2021a) and in a study (N=238 from three laboratories), an initial 16% sex gap in choice to enter competitions was eliminated when the incentives become socially-oriented, with women nearly doubling their entry rate (Cassar & Rigdon, 2021b). These findings have implications for policies designed to promote gender equality based on labor market incentives aligned with women’ goals and respectful of the differential constraints that nature and societies put on the individual.

A Tale of Two Hierarchies: The Dangers of Dominance, the Pitfalls of Prestige

Like the social structures of many other species, the social structures of human groups are organized hierarchically such that some people enjoy greater social influence and respect than other people do. A growing literature in evolutionary psychology suggests that people recruit two distinct strategies – dominance and prestige – to navigate social hierarchies. Whereas dominance relies largely on fear, intimidation, and coercion, prestige relies more on context-specific displays of valued wisdom and skill. This talk will describe recent lines of research, involving both laboratory experiments and longitudinal observations of real social groups, that document ways in which people use dominance and prestige to achieve and maintain high social rank. Findings highlight specific ways in which the use of dominance or prestige can promote – and sometimes undermine – people’s capacity for effective leadership. A secondary goal of the talk is to bridge these lines of work with research from social psychology focusing on the distinction between power and social status.