Center for Behavior, Evolution, and Culture

Kelly Gildersleeve - Meta-analytic and Experimental Investigations of Shifts in Women's Mate Preferences and Attractiveness across the Ovulatory Cycle
2014-05-12 00:00 (America/Los_Angeles)
Kelly Gildersleeve: UCLA Department of Psychology, Center for Behavior, Evolution and Culture For nearly all mammals, the high-fertility period of the ovulatory cycle is the only time when sex can lead to conception. In nonhuman species, this period is often marked by dramatic changes in females’ social interactions. I’ll present two meta-analyses and several lab experiments examining similar effects in humans. Results revealed robust support for differences between high and low fertility in women’s sexual attraction to certain characteristics in men, in some aspects of women’s social behavior (e.g., their flirtatiousness), and in their attractiveness. These findings suggest that women’s mating motivations and the responses they elicit from others are sensitive to their current fertility within the cycle, with potentially important implications for their romantic relationships and social behavior more broadly.

Sam Diaz-Munoz - Tiny tamarins challenge traditional perspectives on sex roles, mating systems, and the evolution of cooperation
2014-05-05 00:00
Sam Diaz-Munoz: UC Berkeley Department of Plant and Microbial Biology and Integrative Biology Tamarins (Saguinus sp) are small Neotropical monkeys that, with other callitrichines, exhibit the most extensive cooperative breeding system of any non-human primate. In this presentation, I will draw on recent studies of tamarins and other callitrichines to underscore the importance of cooperative infant care to their complex social system. I review how callitrichines were originally classified as monogamous, but instead have one of the most flexible social organizations among mammals and birds. I highlight how social organization responds to different ecological conditions and how this flexibility represents a challenge to the concept of the mating system. I suggest that the cost of infant care is a main driver of atypical sexual roles, with intense female reproductive competition and extensive cooperation among males in reproductive contexts. I discuss other species that share elements of social organization with Saguinus tamarins, including humans. Given that increasing evidence points to a cooperatively breeding past for early humans, I advocate for an increasing focus on callitrichines as study systems for understanding the evolution of cooperative behavior in humans and all animal societies.

Jeffrey Schloss - Ecstatic Religious Rituals as Oxytocin-mediated, Hard-to-fake Signals of Cooperative Commitment?
2014-04-28 00:00
Jeffrey Schloss: Westmont College Department of Biology A prominent evolutionary account of “religious cognition” is that it emerged as a byproduct of agency detection mechanisms biased toward false positives, which were exapted as cultural innovations of moralizing gods helped stabilize cooperation by controlling defection in large-scale interactions. Although there is some empirical evidence for this account, along with the concomitant claim that religious rituals function as costly signals of commitment, if the cost of such rituals is less than their benefit, they need not function as honest signals of ascent. This talk will examine the proposal that some kinds of religious rituals associated with autonomically mediated behaviors such as blushing, shivering, fainting, and ecstatic speech, may function as hard-to-fake, though not costly, signals that both convey and promote cooperative intent. I will describe results from experiments in which human subjects engaged in a variety of religious and non-religious group activities – including Pentecostal worship – followed by participation in a series of decision tasks in standard economic games. Indices of trust, trustworthiness, generosity, and conditional responsiveness varied significantly between treatments. Measures of prosociality were correlated with the effect of group activity on plasma oxytocin. I will discuss the implications and limitations of these findings for evolutionary accounts of religion and for our understanding of ritualized group behaviors as facilitators of cooperation.

Josh Tasoff - A Biotic Economics Framework for Microbial Trade
2014-04-21 00:00
Josh Tasoff: Claremont Graduate University School of Politics and EconomicsA significant fraction of all life in the biosphere exists in complex communities in which crossfeeding is essential. In the same way that firms and consumers exchange a vast array of goods in modern markets, organisms exchange essential resources to promote their growth. Here, we present a framework based on general equilibrium theory from economics to predict the population dynamics of crossfeeding microbial communities. Analysis of a special case of the model involving two crossfeeding microbes yields several novel insights: (1) the economic concept of comparative advantage is a crucial condition for trade-based mutualism between species, (2) species that contribute more resources increase their growth rate but at the expense of a lower share of the total population, and (3) the inability to produce essential metabolites (i.e. auxotrophy) can be a selective advantage that explains its prevalence in microbial ecosystems. To test our model experimentally, we construct a synthetic syntrophic consortia of Escherichia coli and manipulate the cells’ ability to exchange essential amino acids. Experimental data are consistent with those generated by our model. This biotic economics framework provides a foundation to tackle key questions in microbial ecology and evolution and has useful applications to engineering synthetic ecosystems.

Christopher Schmitt - The genomics of obesogenic growth during development and adult-onset obesity in captive vervet monkeys: Preliminary results and potential for studies in the wild
2014-04-07 00:00
Christopher Schmitt: UCLA Center for Nuerobehavioral Genetics Obesity is increasingly prevalent worldwide, and has severe negative impacts on public health. Obesity arises from a complex interaction of genetic predisposition and environment that can accumulate throughout life. Although increasing evidence points to the importance of early development in the manifestations of adult disease, few studies have been undertaken of developmental measures that might be associated with adult obesity risk. The search for obesogenic markers during development in humans is complicated by the ubiquity of diets high in fat and simple carbohydrates, and the difficulty in assessing the actual diets of study subjects. This research investigates the genetic underpinnings of adult onset obesity and obesogenic growth trajectories from birth to adulthood in a genetically well-characterized model system under a controlled diet and environment: the African green monkey (Chlorocebus aethiops sabaeus) in the Vervet Research Colony at Wake Forest University.
We currently have some power to identify SNPs associated with these obesogenic traits, but the sample size must be increased. With further sampling, a more detailed examination of growth trajectories, in combination with novel biomarkers such as the SNPs discovered in this study, may be used to assess early obesity risks and promote the discovery of novel biomedical interventions. Perhaps of more interest to evolutionary anthropologists, the results of this captive study could easily be extended to wild populations. Our research group has already sequenced the genomes of hundreds of vervet monkeys from across their ancestral ranges in Africa, and in an isolated wild population on the islands of St. Kitts & Nevis in the Caribbean. This research raises the exciting possibility of assessing phenotypic plasticity and environmental impacts on trait expression in the wild associated with SNPs that are obesogenic in captivity.

Fei Xu - Towards a rational constructivist approach to cognitive development
2014-03-31 00:00
Fei Xu: UC Berkeley Department of Psychology, Infant Cognition and Language LabThe study of cognitive development has often been framed in terms of the nativist/empiricist debate. Here I present a new approach to cognitive development: rational constructivism. I will argue that learners take into account both prior knowledge and biases (learned or unlearned) as well as statistical information in the input; prior knowledge and statistical information are combined in a rational manner (captured by Bayesian probabilistic models); and there exists a set of domain-general learning mechanisms that give rise to domain-specific knowledge. Furthermore, learners actively engage in gathering data from their environment. I will present evidence supporting the idea that early learning is rational, statistical, and inferential, and infants and young children are rational, constructivist learners.

Peter Todd - Domain-specific mechanisms for decisions about food
2014-03-10 00:00
Peter Todd: Indiana University Department of Psychological and Brain Sciences The need to find nourishing foods is a selective pressure that may have shaped many human cognitive processes, from perception to memory. In this talk, I present some of our efforts to uncover such domain-specific influences. Hurlbert and Ling (2007) suggested that an ancestral sexual division of labor, with foraging females seeking out ripe fruits, could have led to a cross-cultural female preference for red hues. We have developed a novel approach to studies of sex differences and culture differences in color preference by analyzing the hue distributions of a large database of over 20 million color photographs on Flickr taken by men and women. While we find a general red-hue preference among women across cultures, we cannot attribute it to food-based images. In another study, we have found top-down influences of hunger on perceptual categorizations of edible versus non-edible items. Finally, we have been testing whether memory for recently eaten foods may be designed to let individuals track and respond to items that make them sick, leading to a forgetting pattern different from the usual decelerating decay seen in other domains.

Megan Robbins - The Little Things in Life: An Observational Perspective on Everyday Coping
2014-03-03 00:00
Megan Robbins: UC Riverside Department of Psychology This talk discusses the potential of a novel naturalistic observation method, the Electronically Activated Recorder (EAR), for studying health-relevant social processes. The EAR is a portable audio recorder that periodically records snippets of ambient sounds from participants’ momentary environments. In tracking moment-to-moment ambient sounds, it yields acoustic logs of people’s days as they naturally unfold. In sampling only a fraction of the time, it protects participants’ privacy and makes large-scale observational studies feasible. As a naturalistic observation method, the EAR provides an observer’s account of daily life, which renders it optimal for studying the role of automatic expressive behaviors (e.g. sighing, swearing, laughing) and habitual communication processes (e.g. we-talk) in the coping context. I will first highlight findings regarding the role of sighing, swearing, and laughing in the coping process. Then, I will present recent results from a study of the daily social interactions of couples coping with breast cancer.

Morteza Dehghani - #morality in 140 Characters: Examining Moral Rhetoric in Text
2014-02-24 00:00
Morteza Dehghani: USC Brain and Creativity Institute, ARTIS Research FellowThe availability of vast and seemingly insurmountable volumes of human-related data has provided an unprecedented opportunity to study human cognition with range and detail previously not imaginable. An enormous amount of such data, however, is in the form of human generated text, and cannot be analyzed directly. As a result, there has been rapid developments in automated text analysis methods focused on measuring psychological and demographic properties. In this talk, I will present a computational text analysis technique for tracking and measuring transformations in moral concerns with regards to different social-cultural issues, and for examining the moral dimensions of different debates using text. This technique uses Latent Semantic Analysis to compute the semantic similarity between concepts of interest and moral keywords taken from the Moral Foundation Dictionary (Graham, Haidt & Nosek, 2009). I will specifically focus on analyzing Twitter data regarding the 2013 federal government shutdown. Our results demonstrate that using moral loadings of tweets we can make various accurate predictions about Twitter users and communities.

Kirk Lohmueller - Discovering Recent Human History and Natural Selection from Genetic Variation Data
2014-02-10 00:00
Kirk Lohmueller: UCLA Department of Ecology and Evolutionary BiologyIt is commonly quoted that any two humans are identical at 99.9% of their three billion DNA letters. However, this statement also means that there are roughly three million positions where any two genomes are different. Many such variants have been accumulating throughout hundreds of thousands of years of human evolution and provide a record of human history. Additionally, many of these variants acting together will affect how many children an individual will have or may contribute to the risk of common diseases. Here I will describe two projects aimed at learning about human history and natural selection from genetic variation data. First, through the analysis of genetic variation in the coding regions of genes obtained from 1500 Han Chinese and Danish individuals, I find evidence for extreme, recent, population growth in both populations. However, this growth appears to have been greater in the Han Chinese than in the Danes. The second project is based on the analysis of genetic diversity on the human Y chromosome. We find that genetic diversity is substantially lower than expected on this chromosome. Sex-biased demographic processes throughout human history cannot, by themselves, explain this reduction in genetic diversity. Rather, natural selection removing deleterious mutations from nearly 4Mb of the Y chromosome, or natural selection increasing the frequency of beneficial mutations is required to explain the data.

Jacinta Beehner - Changes in female reproductive condition following the arrival of new males in geladas: A physiological trifecta?
2014-01-31 00:00
Jacinta Beehner: University of Michigan Department of Anthropology The arrival of a new dominant male can be a tumultuous time for females in a primate social group – particularly when this male is likely to be infanticidal. Females of many taxa where infanticide occurs have developed counterstrategies to this threat. In sharp contrast with the behavioral counterstrategies reported for many primate species, we discovered that female gelada responses are almost entirely physiological. Using 7 years of demographic and hormonal data from a population of wild geladas living in the Simien Mountains National Park, Ethiopia, I will detail two of these strategies – “false fertility” employed by lactating females, and pregnancy termination (a “Bruce effect”) employed by pregnant females. Completing the trifecta, I will present preliminary data that adolescent females exhibit yet a third physiological response to the arrival of a new male – the sudden onset of maturation (a “Vandenbergh effect”). I revive a term previously proposed for these same effects (the “hoo haa effect”) because there is likely a singular mechanism mediating all three outcomes.

Thomas Plummer - Oldowan Archeology on the Homa Peninsula, Kenya, or what 2 million year old trash tells us about hominin behavior
2014-01-27 00:00
Thomas Plummer: Queens College Department of Anthropology, member of CUNY graduate faculty and New York Consortium in Evolutionary PrimatologyHumans are odd primates. We have unusually large brains, a diet rich in hard-to-acquire, nutrient dense foods, we practice extensive food sharing, and we can adapt to a broad panorama of environments through cultural practices and social institutions. Whereas other primates may exhibit culture, and produce technologies that assist in foraging, humans are unique in being dependent on cultural practices for survival. But how far back in time does this dependency on culture go? What was the adaptive significance of early stone technologies? In this talk I will describe research on two million year old archeological sites on the Homa Peninsula, Kenya. This research sheds light on early hominin foraging ecology at the dawn of the genus Homo.

Dario Maestripieri - Understanding human life history variation: sleep patterns, personality traits, relationship status, and hormones.
2014-01-23 00:00
Dario Maestripieri: University of Chicago, Department of Comparative Human Development; Institute for Mind and BiologySeveral lines of evidence suggest that eveningness is associated with traits that favor short-term mating such as higher extraversion, novelty-seeking, risk-taking, and short-term relationship orientation in both males and females. Night owl men also report a higher number of sexual partners than early-morning men, who instead, show personality and behavioral traits typically associated with slow life histories. Evidence also exists that autistic-like and schizotypal personality traits reflect opposite sides of a continuum of variation in personality and cognition that are best understood in reference to other slow and fast life history adaptations. Cortisol and testosterone may be some the physiological mechanisms underlying psychological and behavioral traits associated with slow and fast life histories. Both cortisol and testosterone levels differ between individuals who are single and in relationships, with cortisol being associated with some aspects of personality and stress, while men’s testosterone is more directly linked to variation in courtship activity and sexual promiscuity.

Robert Watson - Conservatism and Creativity in Cultural Evolution: A View from the Arts and Humanities
2014-01-13 00:00
Robert Watson: UCLA Department of English Creative arts and humanistic learning allow us to vary, evaluate, and regulate the evolving cultural systems that we empower, at some cost and risk, to protect us from the unique openness of human consciousness. Culture takes over the conservative tasks (performed biochemically in most non-human creatures) of giving shape to the overwhelming data offered by the world and providing coherent instructions for responding. Yet high culture (both artistic and scholarly) helps the broader culture co-evolve with us, offering a safe setting for experimental innovations, selecting which latent parts of our epigenetic library should be activated in a particular environment, and favoring variations that promote long-term diversity over self-serving viruses that commandeer the body-politic into narrowing, inhumane projects. Universities provide an essential defense both against the reactionary tribalism that resents complexity and multiculturalism, and against the runaway meme-complexes now often manifest in capitalism and religion.

Paul Rozin - Reflections on Cultural and Evolutionary Psychology
2014-01-09 00:00
Paul Rozin: University of Pennsylvania, Department of Psychology None Available

Pamela Smith - The Social Distance Theory of Power
2014-01-06 00:00
Pamela Smith: UC San Diego Rady School of Management, Professor of Management and Strategy I propose that individuals with higher power should view the world in a more high-level, abstract fashion than individuals with lower power (Magee & Smith, 2013). As having power makes individuals less dependent on others (relative to lacking power), it increases the psychological distance one feels from others, and this distance (according to construal level theory) should lead to more abstract information processing. Thus, those with power think in terms of the “big picture,” focusing more on primary, goal-relevant aspects of stimuli and moving beyond the details to see patterns and structure, than those without power. In my talk I will review several studies that demonstrate this effect. Then I will discuss more recent research that has explored the intrapersonal and interpersonal implications of these effects for domains such as perceived power, forgiveness, and executive functioning.

Jay Belsky - Childhood Experience and the Development of Reproductive Strategies: An Evolutionary Theory of Socialization Revisited
2013-12-02 00:00
Jay Belsky: UC Davis Department of Human Ecology, Human Development and Family Studies Program An evolutionary biological perspective on the effects of the extra-familial and familial environment on multiple psychological, behavioral and even somatic features of children’s development challenges prevailing thinking about human development which regards some contextual conditions and their sequelae as “good” and others as “bad”. Theory and research on the development of human reproductive strategies based on such evolutionary thinking has developed substantially over the past two decades. Here I review two decades of theory development and research findings pertaining to the development of reproductive strategies, highlighting the contextual regulation of pubertal timing, the distinctive role of father, differential susceptibility to rearing influences, mechanisms of influence and new ways of conceptualizing the environment, while outlining future directions for research.

Andy Sih - Three Frontiers in the Study of Behavioural Syndromes (aka Animal Personalities)
2013-11-25 00:00
Andy Sih: UC Davis Department of Environmental Science and Policy Over the past decade, a rapidly growing number of studies have shown that animals often exhibit personalities; e.g., where some individuals are consistently more aggressive, bold, active, exploratory or social than others. Here, I present theory, data and ideas on three ‘frontiers’ in the study of the ecological and evolutionary implications of this phenomenon. First, I discuss a theoretical/conceptual framework for explaining variation in the phenomenon. Why are individuals sometimes very consistent (stable) in their personality, but other times, less so? When do we expect early experiences to have large effects on later personality, versus when do we expect little or no lasting effect of early experiences? Second, I examine the interaction between individual behavioural types (BTs) and the social situation in determining individual behaviours and fitness outcomes (mating success). This section raises issues about group selection on personalities, keystone individuals, social skill and rapidly reversible mating systems. Finally, I present data and ideas on a key ecological implication of behavioural syndromes – the effect of behavioural type dependent dispersal on ecological invasions and spatial ecology, in general.

Dwight Read - How Culture Makes Us Human: From Experiential-Based to Relational-Based Forms of Social Organization
2013-11-18 00:00
Dwight Read: UCLA Department of AnthropologyThe theme of my talk centers on the evolutionary changes that distinguish human social systems from those of our non-human primate ancestors—are we simply the next step in the phylogenetic sequence that leads to our evolutionary development as a species, or did the innovation that we refer to as culture introduce a definitive turn in that evolutionary sequence? I will develop an answer to this question by tracing out the evolutionary pathway from our non-human primate ancestors to the beginnings of the culture-based systems of social organization that characterize human societies. In this account, I assess the validity of each of two main ways to characterize that evolutionary pathway. The first sees us as simply an extension of the evolutionary pattern observable in the phylogenetic sequence leading to our species through our hominin ancestry, including elaboration on the rudiments of culture found among the non-human primates, especially the chimpanzees. The second views the transition to human societies as analogous to a phase shift, hence models of the evolutionary development of social systems among the non-human primates do not provide, by themselves, a secure foundation for understanding the subsequent evolutionary development of the relation-based systems of social organization that characterize human societies, with their likely beginning in the Upper Paleolithic. I conclude by discussing some of the implications the latter has for models of for the evolution of human social and cultural systems.

C. Randy Gallistel - The Perception of Probability
2013-11-04 00:00
C. Randy Gallistel: Rutgers University Department of Cognitive Psychology I present a computational model to explain the results from experiments in which subjects estimate the hidden probability parameter of a stepwise non-stationary Bernoulli process outcome by outcome. The model captures the following results qualitatively and quantitatively, with only two free parameters: 1) Subjects do not update their estimate after each outcome; they step from one estimate to another at irregular intervals. 2) The joint distribution of step widths and heights cannot be explained on the assumption that a threshold amount of change must be exceeded in order for them to indicate a change in their perception. 3) The mapping of observed probability to the median perceived probability is the identity function over the full range of probabilities. 4) Precision (how close estimates are to the best possible estimate) is good and constant over the full range. 5) Subjects quickly detect substantial changes in the hidden probability parameter. 6) The perceived probability sometimes changes dramatically from one observation to the next. 7) Subjects sometimes have second thoughts about a previous change perception, after observing further outcomes. 8) The frequency with which they perceive changes moves in the direction of the true frequency over sessions. The model treats the perception of the current probability as a byproduct of the construction of a compact encoding of the experienced sequence in terms of its change points. It illustrates the why and the how of intermittent Bayesian belief updating and retrospective revision in simple perception.

Karen Kramer - When Mothers Need Others. The Evolution of Parenting, Childhood & Cooperation
2013-10-28 00:00
Karen Kramer: University of Utah Department of Human Evolutionary Biology Human life histories differ from those of other closely related species in ways that significantly affect parental care and childhood. Most explanations for the hominization of life histories incorporate ideas about social interdependence and cooperative breeding. While cooperation for the purposes of raising children is often presumed to be ancient, it leaves no known fossil record or genetic signature. To address this empirical gap, I will first discuss the evolution of parenting and childhood, and then develop a simulation that looks at the question, when do mothers need others? I will conclude by asking what is it that we can actually say about the past, and suggest from model results that an age division of labor and exchanges between mothers and juveniles are an important gateway in the evolution of human sociality and cooperation.https://docs.google.com/viewer?a=v&pid=gmail&attid=0.1&thid=141e1e4c99b38333&mt=application/pdf&url=https://mail.google.com/mail/u/0/?ui%3D2%26ik%3D49bcb6aeab%26view%3Datt%26th%3D141e1e4c99b38333%26attid%3D0.1%26disp%3Dsafe%26zw&sig=AHIEtbQrR-sW3OQ5YGN4zMmkW5gWeuzd0A

Eli Berman - Predation, Taxation, Investment and Violence: Evidence from the Philippines
2013-10-21 00:00
Eli Berman: UCSD Department of Economics This paper explores the relationship between investment and political violence through several possible mechanisms. Investment as a predictor of future violence implies that low private sector investment today provides a robust indicator of high violence tomorrow. “Rent-capture” or predation asserts that investment increases violence by motivating extortion by insurgents. A “hearts and minds” approach links investment to political violence in two possible ways: through an opportunity cost mechanism by which improved economic conditions raise the cost of rebel recruitment; and through a psychological “gratitude” effect which reduces cooperation of noncombatants with rebels. Finally, tax capture implies that government will increase coercive enforcement in an attempt to control areas where increased investment increases tax revenue. We lay out these mechanisms in a framework with strategic interaction between rebels, communities, government and firms within an information-centric or “hearts and minds” counterinsurgency model. We test these mechanisms in the context of the Philippines in the first decade of this century, using information on violent incidents initiated by both rebels and government and new data on industrial building permits, an indicator of economic investment. Increases in investment are positively correlated with both rebel and government initiated violence. In the context of our theory that constitutes unequivocal evidence of predation, is consistent with tax capture, and weighs against predictive investment, opportunity costs or gratitude being a dominant effect.

Andrew Gersick - Courtship Signaling in a Social Context: What Flirting and “Flirting” May Do for Humans, Birds and Others.
2013-10-17 00:00
Andrew Gersick: University of Pennsylvania Department of Animal BehaviorSexual selection is widely understood through the lens of the peacock’s tail – as the evolutionary driver shaping elaborate
courtship displays and signals. Less studied is the influence of sexual selection on cognitive abilities or behaviors that allow individuals to regulate how they use those signals. Prevailing theory suggests, for example, that courting males always present their sexually selected signals at maximum intensity and thus exhibit their capacity to bear the associated signaling costs. Yet many social creatures face shifting competitive contexts that would reward more flexible control over signaling behavior. Humans are an obvious example: we conduct our courtship within complex networks of potential eavesdroppers, many of whom may have an interest in our sexual signaling efforts. I propose that the covert linguistic signals we call flirtation are an adaptive response to the shifting competitive pressures that surround human courtship. I will also discuss experiments with another social class of animals with a sophisticated communication system – songbirds – demonstrating that humans’ flexible signaling is far from unique.

David Nolin - What goes around comes around? Cyclicity as a statistical test of generalized reciprocity in social network data.
2013-10-14 00:00
David Nolin: Boise State University Department of AnthropologyGeneralized (indirect) reciprocity is characterized by giving to other group members without regard to direct reciprocation from those same recipients, with the costs of the donor’s generosity instead offset by transfers from other group members. This pattern has long been noted by anthropologists as a common feature of foraging societies; however, there have been relatively few quantitative tests of the principle. One basic test is to see if what one gives is correlated with what one receives – a correlation of indegree and outdegree in network terminology. However, a more specific test is to look for evidence of cycles in the network: A gives to B, who gives to C, who gives back to A. Using between-household food-sharing data from the fishing and whaling village of Lamalera, Indonesia, I test for evidence of cyclical exchange. Previous analyses have shown strong support for direct (dyadic) reciprocity in this population but this additional analysis finds no evidence of cyclical exchange. Instead,there is a significant propensity to form transitive triads (A gives to both B and C, and B also gives to C). This result is compared to ethnographic observations of social support via food transfers from economically secure to chronically needy households.

Richard McElreath - The endogenous Dorito: The cultural evolution of evolutionary mismatch
2013-10-07 00:00
Richard McElreath: UC Davis Department of AnthropologyIt’s common for evolutionary psychologists to invoke evolutionary mismatch as an explanation for maladaptive human behavior. For example, people eat themselves to death, because our food preferences evolved in a past environment with scarcity. Mismatch has also been invoked to explain the tendency for humans to cooperate with strangers and non-kin, and mismatch is usually presented as an alternative to cultural evolutionary processes, such as cultural group selection. I argue that every example of evolutionary mismatch is a study in cultural evolution and likewise that every example of cultural evolution is a study in evolutionary mismatch. The two processes cannot usually be separated in analysis, as successful cultural institutions and beliefs are adapted to evolved human psychology. Likewise, evolved psychology alone is an insufficient explanation, because cultural forms evolve to manipulate it.

Lee Cronk - Our cultural immune system: Toward a theory of culture’s influence on behavior
2013-09-30 00:00
Lee Cronk: Rutgers University Department of AnthropologyAnthropologists are rarely able to predict when a culture trait will influence behavior and when it will not. The theory of gene-culture coevolution leads to the prediction that we should have something akin to an immune system for culture that helps us make adaptive decisions regarding which culture traits to resist and which to allow to shape our behavior. Understanding our cultural immune system will require us to define culture in a way that separates it from behavior, consider the impacts of individual culture traits on behavior rather than treating culture as an undifferentiated whole, and focus on culture traits that have clear behavioral referents. One way to examine the impacts of individual culture traits on behavior is to transfer them from the societies in which they originated to new ones and then assess their impacts on behavior. I have used this technique in a series of studies using a Maasai gift-giving norm. The impact of the norm on behavior is revealed through experimental games framed in terms of the norm played by both Maasai men and American college students. The results suggest that even unfamiliar social coordination norms may easily influence behavior across societies but that this effect depends crucially upon exactly how the norm is framed.

Matthew Gervais - Mapping an egalitarian hierarchy: relational economic games tap RICH norms of helping and leveling in a Fijian village
2013-06-03 00:00
Matthew Gervais: The University of California, Los AngelesExperimental economic games have shed significant light on human population variation in social behavior. However, most of these games have involved anonymous dyadic recipients, limiting their external validity beyond fleeting pairwise interactions. Yet enduring relationships within large social networks are arguably the cradle of human uniqueness and remain the cornerstone of human adaptation across societies. Mapping the mechanisms that structure social behavior within human communities will require methods that have the virtues of economic games – including incentivized behavior, and replicability and comparability across populations – but which integrate multiple identifiable recipients and thereby tap Recipient Identity-Conditioned Heuristics (RICHs) such as direct and indirect reciprocity, trait- and state-based notions of fairness, and kinship norms. This talk describes three “relational” economic games that integrate recipient identities and other-other tradeoffs, and reports their validation in a study of male social relationships in a Fijian village. The three games, an Allocation Game, a Taking Game, and a Costly Reduction Game, involve monetary decisions made across a photo array of other villagers. Levels of both altruism and spite in these games are higher than those documented using dyadic anonymous games in neighboring villages. Recipient need is the major driver of giving and refraining from taking, while the wealthiest villagers are the mostly likely to be reduced at a cost, especially if they lack “Chiefly” character. Such need-based giving and leveling are hallmarks of human egalitarianism, and are well attested to in Fijian ethnography. Moreover, dyadic attitudes such as love, respect, hate, and fear partially mediate helping and punishing others, illuminating the psychological processes that regulate Fijian relationships. Relational economic games thus hold promise for mapping population variation in RICH norms and the mechanisms supporting cooperation within human communities, significantly advancing the toolkit of a scientific anthropology.

Monique Borgerhoff-Mulder - Responding to Inequality: Cooperation, Kinship and Witchcraft in Mpimbwe, Tanzania
2013-05-20 00:00
Monique Borgerhoff-Mulder: University of California, DavisWhile the causes, transmission and consequences of material and social inequality are well studied in the social sciences, the ways in which people respond to inequality are less clear. As evolutionary social scientists we know that humans show a strong aversion to inequality, but we have little understanding of how individuals respond behaviourally to disparities in material, social and relational wealth. In this talk I present data from the Pimbwe, a Bantu forager-horticulturalist population in Tanzania undergoing rapid social change and escalating material inequality, to show how both witchcraft accusations and social networks of exchange are patterned by wealth differences. Specifically cooperation among unrelated and related individuals is least pronounced amongst the wealthiest individuals. This observation is used to start theorizing how inequities might favor or disfavour cooperation. A better understanding of such dynamics is important, given the escalating levels of inequality worldwide, consequential on the neoliberal policies associated with globalization.

Steven Stroessner - Confronting Threat When Safety Concerns are Paramount
2013-05-15 00:00
Steven Stroessner: Barnard College, Columbia UniversityMotivations are generally concerned with maintaining safety (prevention) or ensuring advancement (promotion) (Regulatory focus theory; Higgins, 1997). Four experiments examined whether information implying imminent threat would interact with regulatory focus to affect endorsement of stereotypes and stereotype-based policies. Because threatening information is more relevant to the safety goals of prevention-focused individuals than the advancement goals of promotion-focused individuals, endorsement of threat-relevant stereotypes was expected to increase under high threat but only for people operating under a under prevention focus. Support for this prediction was obtained in four distinct and socially important domains. In three experiments, prevention-focused individuals made judgments and endorsed policies consistent with stereotypes when threat was perceived to be high rather than low. In a fourth experiment in which the stereotypicality of the target was manipulated, only prevention-focused individuals were more likely to endorse scrutinizing a target stereotypically associate with danger under high threat conditions. Across the experiments, promotion-focused individuals tended to exhibit less stereotyping under high threat, suggesting that they were engaged in systematic processing under low regulatory fit. These results demonstrate that safety concerns produce vigilance toward threats in the social environment, but that responses to threat vary with its perceived imminence. Threat-relevant stereotypes are utilized when safety concerns are paramount.

Claire White - Evolutionizing Bereavement Research: Toward an Integrated Account of Human Grief
2013-05-13 00:00
Claire White : California State University, NorthridgeGrief is a universal reaction to the loss of a valued relationship partner. Two main evolutionary accounts of grief have been proposed. The first views grief as a by-product of an adaptive separation reaction that functions to aid unification in the temporary loss of a valued relationship partner. The second posits that grief is an adaptation that evolved to cope with the loss of a loved one by changing goals, signaling to others to enhance social support and reassessing one’s current behaviors, relationships and priorities. Despite the potential of evolutionary accounts to inform research, they have not been integrated into mainstream bereavement literature. This state of affairs is in part because evolutionary theories of grief lack theoretical clarity, empirical predictions and supporting evidence. The aim of this talk is to highlight these weaknesses and to begin to correct for them. The talk is divided into three parts. First, I critically evaluate the two leading evolutionary theories of grief. Second, I analyze the goodness-of-fit between the predictions generated from these two contrasting approaches and findings in bereavement research, including data from a series of studies that I have conducted. Third, and finally, I propose a new evolutionary account of grief that integrates existing theories by disaggregating the core symptoms after the experience of bereavement into evolutionarily meaningful subtypes.
