Cooperation, Conflict, and Social Choices in Capuchin Monkeys

Human cognitive abilities are remarkable, but not exceptional. In light of evolution, humans are an extreme primate on one end of an already-sophisticated spectrum. One hypothesis for explaining the evolution of primate cognition is that living in groups selected for a “social
mind”, a larger brain and complex cognitive abilities to aid in solving a myriad of social challenges. This hypothesis has garnered considerable support from experimental paradigms in captivity, however, these studies often control against normal social interactions. Understanding the selective pressure of social challenges on primate cognition requires studying the social mind in a social context. My research examines how nonhuman primates
make decision in their social world and what factors impact these choices. I approach these questions from an evolutionary perspective while utilizing a mechanistic approach, through the integration of experimental paradigms in the wild, and the analysis and manipulation of hormones. In this talk, I focus on decision-making during cooperation and conflict, two situations in which making the wrong choice can have significant fitness consequences. First, I examine how conflict influences cooperation in capuchin monkeys, and the role of oxytocin in promoting cooperation during conflict. Second, I present novel methods to examine experimental cognition and decision-making in wild primates. By combining the best aspects of field work, highlighting the emergence of social challenges, and the best aspects of controlled experiments, highlighting the mechanisms of social choices, my research offers a promising
avenue for understanding the importance of sociality, cooperation, and conflict on primate cognitive evolution.

Evolved Optimality: The Synthesis of Error Management Theory and Signal Detection Theory to Study Evolved Biases ​

Error management theory (EMT) broadly states that decisions repeatedly made under uncertainty result in evolutionarily strategic biases that reduce costs, maximize benefits, or both, even if it produces more errors overall. At its core, EMT bears many similarities to Signal Detection Theory (SDT) which describes how the presence or absence of a signal is judged while in noisy or uncertain environments. A synthesis of EMT and SDT can help researchers better understand evolved biases, such as sexual overperception, commitment skepticism, and overperception of venomous animals. This talk will present the results from several studies combining SDT and EMT to establish a more nuanced way of evaluating bias that incorporates a measure of cue discriminability, avoids the pitfalls of difference scores, tests novel hypotheses that could not be generated by either theory alone, and allows for the comparison of biases across topic areas.

A Moral Tradeoff System Produces Intuitive Judgments that are Rational, Coherent, and

Strike a Balance Between Conflicting Moral Values

Hominin social life routinely created moral dilemmas. For many, striking a balance between two competing moral obligations by partially satisfying both (a compromise judgment) would have promoted fitness better than neglecting one to fully satisfy the other (an extreme judgment). Making adaptive judgments required a moral tradeoff system (MTS): a cognitive system that weighs the conflicting moral values, and uses the resulting representation to identify, from the available solutions, the one that is most right (Guzmán et al., PNAS 2022). We drew on rational choice theory to develop a cognitive model of how a well-designed MTS should work; it should
produce rational judgments, even when striking a balance that results in compromises. We tested the model using revealed preference methods and a sacrificial moral dilemma. This allowed a critical test between the MTS hypothesis and an influential dual process model, which claims that sacrificial dilemmas activate a “non-negotiable” emotion that prevents compromises. Each
subject considered 21 scenarios, which varied the human cost of saving lives, each with 2-7 possible resolutions. When asked which is morally right, many people made compromise judgments, contradicting the dual process model. Moreover, their judgments satisfied the axioms
of rational choice, no matter how many compromise judgments they made. This highly improbable result cannot be produced by deliberative reasoning; it is the signature of an optimizing algorithm. As the MTS model predicts, judgments were intuitive, yet rational: People
consistently identified the resolution that is most right, given how their minds weighed the competing moral values.

Inside the Supergene of the Bird with Four Sexes​

The white-throated sparrow (Zonotrichia albicollis) offers unique opportunities to understand mechanisms underlying the evolution of social behavior. In this species, alternative plumage morphs are associated with a segment of chromosome 2 that has been called a ‘supergene’. Because the supergene occurs equally in males and females, and because each breeding pair in the wild consists of one individual with the supergene and one without it, this species has been called the “bird with four sexes.” The supergene is associated with a behavioral phenotype; birds with the supergene are more aggressive and less parental than birds without it. In this talk, I will present the results of our efforts to identify genes inside the supergene that are responsible for this behavioral polymorphism. We hypothesize that two genes in particular, ESR1 and VIP, contribute to behavior in a coordinated way and could represent co-adapted alleles. Because the supergene contains more than 1000 individual genes, this species provides rich possibilities for discovering alleles that work together to mediate life-history trade-offs and maximize the fitness of alternative complex phenotypes.

Comfort Around Strangers: The Turning Point in Human Prehistory that Made Huge Societies Possible

An essential feature of any society is the capacity of its members to distinguish one another from outsiders and exclude foreigners on that basis. In most species that live in societies, the members must recognize each other as individuals. I contrast such "individual recognition societies” with the societies of humans and a few other animals in which membership can be anonymous, a condition that, under suitable conditions, makes possible enormous populations. How and why anonymous societies emerged in our ancestors is a question of significance for psychologists, anthropologists, biologists, and sociologists.

Life History Theory and Adult Outcomes:

Evidence from the Minnesota Longitudinal Study

of Risk and Adaptation

Life history theory (LHT) is a broad, meta-theoretical approach to understanding how certain kinds of experiences encountered earlier in life may be prospectively associated with certain social development outcomes later in life. In this talk, I first review core principles of LHT and then discuss longitudinal studies that have tested hypotheses derived from Belsky, Steinberg, and Draper’s (1991) Evolutionary Model of Social Development. Working with lifespan data from the Minnesota Longitudinal Study of Risk and Adaptation, we have examined how exposure to unpredictable (versus harsh) early-life environments are prospectively related to risk-taking, mating, and parenting in adulthood. These studies reveal the mediation pathways through which exposure to early-life unpredictability in particular is associated with these important adult outcomes.

Value Computation in Humans​

The variables cost and benefit are of central importance in selectionist models. Evolutionary psychology, neuroscience, and other disciplines have added much to our understanding of how humans represent and estimate these variables and carry out biological processes on the basis of their corresponding estimates. But many questions, including basic ones, remain unanswered. Things afford positive, neutral, or negative long-run effects on the replicative probability of the focal individual’s genes. At the most general level, values are internal estimates of those effects. Value information steers physiology and behavior in the right direction: approach apple, avoid lion. Thus, value computation is of paramount biological importance. Task analysis suggests human evaluative psychology is fantastically complex. There are many prerequisites for valuing things aptly. Here, I focus on two: the need to compute value accurately, and the need to properly feed and integrate value information into the various systems that use value information in their computations (e.g., emotion systems). For example, the subjective food value imputed to an apple needs to reflect the nutrient content of the apple (accuracy); the intensity of gratitude aroused if someone gave you an apple needs to reflect the food value imputed to the apple (integration). Here, I evaluate these hypotheses with two preregistered studies. Consistent with the integration hypothesis, there are close correspondences between (i) the food values that participants impute to each of 40 food items (Study 1; goods) and (ii) the social values and the social emotions (including: gratitude, anger, shame, and pride) that result when those food items occur as constituents of broader social events. Similar correspondences are observed when participants evaluate each of 28 diseases and injuries (Study 2; bads). Consistent with the accuracy hypothesis, exploratory analyses indicate that the food values, the social values, and the social emotions elicited by the food items all track the nutrient content of those food items. Valuation in organisms is inherently a computational process. For this reason, a computational–adaptationist perspective is distinctively suited to spur progress in our understanding of value computation in humans.