Christina Palmer - Maternal-Fetal Genotype Incompatibility as a Risk Factor for Schizophrenia
2012-11-19 00:00 (America/Los_Angeles) | CA
Christina Palmer: The University of California, Los AngelesPrenatal/obstetric complications are implicated in schizophrenia susceptibility. Some complications may arise from maternal-fetal genotype incompatibility, a term used to describe maternal-fetal genotype combinations that produce an adverse prenatal environment. As will be described, maternal-fetal genotype incompatibility can occur when maternal and fetal genotypes differ from one another, or when maternal and fetal genotypes are too similar to each other. Incompatibility genes for each of these scenarios have been implicated as risk factors for schizophrenia and a review of maternal-fetal genotype incompatibility studies suggests that schizophrenia susceptibility is increased by maternal-fetal genotype combinations at the RHD, ABO, and HLA-B loci. Maternal-fetal genotype combinations at these loci are hypothesized to have an effect on the maternal immune system during pregnancy, which can affect fetal neurodevelopment and increase schizophrenia susceptibility. During this presentation, data will be synthesized and the hypothesized biological role of these incompatibility genes in the etiology of schizophrenia will be described.

Georg Striedter - What's Special About Human Brains?
2012-11-26 00:00
Georg Striedter: The University of California, Irvine. Human brains are much larger than one would expect for primates of our body size. They also feature more neurons and a proportionately larger neocortex. Prefrontal cortex, in particular, is significantly larger in humans than in other species. Although these features make the human brain unique, most of them are in line with allometric expectations, meaning that they can be predicted from the large size of our brains. Thus, human brains are fairly typical primate brains; they just became unusually large. Nonetheless, there are good reasons to believe that the evolutionary expansion of the human brain, especially of prefrontal cortex, caused evolutionary changes in neural connectivity and function. Dr. Striedter will review some of the evidence supporting this idea and place it in the larger context of brain and behavioral evolution.

Scott A. Reid - Perceived Distance Between Accents, Religious Groups, and Attraction to Ingroup-Accented Speakers, is Calibrated to the Costs of Infection Risk
2012-12-03 00:00
Scott A. Reid: University of California, Santa BarbaraThere is evidence that humans have adaptations to avoid outgroup members who potentially harbor novel pathogens. However, intergroup contact can produce fitness costs (e.g., violence and disease), or benefits (e.g., trade, mates, and technologies), which suggests that it would be beneficial to possess an adaptation that enables the accurate tracking of group memberships. We predicted that accurate group tracking is accomplished through cognitively differentiating between social groups, and that this differentiation would be calibrated to the potential risk of infection. Consistent with this hypothesis, we found that increases in pathogen disgust are associated with increases in perceived similarity to ingroup-accented speakers and perceived dissimilarity from outgroup-accented speakers, particularly after exposure to pathogenic stimuli. Further, the effect of pathogen disgust on the accuracy of social categorization was mediated by intergroup differentiation. In this talk I present evidence for this group tracking hypothesis for accents, as well as recent evidence that extends the hypothesis to perceptions of similarity to religious groups, and to female judgments of the sexual attractiveness of ingroup- over outgroup-accented male speakers.

Aaron Lukaszewski - The Origins of Heritable Personality Variation: An Integrative Evolutionary Approach
2013-01-07 00:00
Aaron Lukaszewski: Loyola Marymount UniversityTwo basic questions in the study of personality origins are (1) Why do people vary in their personality trait levels? and (2) Why do distinct trait dimensions covary in consistent patterns within individuals, rather than varying independently? The current presentation describes an integrative evolutionary framework within which both of these questions can be addressed, and highlights supportive empirical findings. For instance, since physical strength and physical attractiveness likely predicted the reproductive payoffs of extraverted behavioral strategies across most of human history, it was theorized that extraversion levels are facultatively calibrated to variations in these phenotypic features. Confirming these predicted patterns, strength and attractiveness together explained a surprisingly large fraction of the variance in extraversion in Studies 1 and 2 – effects that were independent of variance explained by an androgen receptor gene polymorphism. Study 3 then provided evidence that the covariation among a wide array of interpersonal traits (e.g., extraversion, emotionality, attachment styles) is orchestrated by their facultative calibration in response to common input cues. Overall, these findings suggest that multiple types of proximate mechanisms – facultative calibration and specific gene polymorphisms – operate in concert to determine adaptively-patterned personality (co)variation. http://bec.ucla.edu/papers/Lukaszewski_BEC.pdf

James W. Pennebaker - Using function words to understand people, groups, and culture
2013-01-14 00:00
James W. Pennebaker: University of Texas at AustinThe smallest and most frequently used words in English are function words — pronouns, prepositions, articles, auxiliary verbs, etc. These overlooked words are profoundly social and can signal the ways people think, feel, and relate to others. Using a variety of text analysis methods, it is possible to track function words to deduce an author’s age, sex, social class, personality, honesty, status, and emotional state. By analyzing ongoing interactions, the degree to which couples, groups, or larger entities are listening to and effectively communicating with others can be estimated. The function word analytic approach has interesting implications for research projects in the social sciences, humanities, education, business, medicine.

Mark Handcock - Statistical Modeling of Social Networks
2013-01-28 00:00
Mark Handcock: University of California, Los AngelesIn this talk we give an overview of social network analysis from the perspective of a statistician. The networks field is, and has been, broadly multidisciplinary with significant contributions from the social, natural and mathematical sciences. This has lead to a plethora of terminology, and network conceptualizations commensurate with the varied objectives of network analysis. As the primary focus of the social sciences has been the representation of social relations with the objective of understanding social structure, social scientists have been central to this development. We illustrate these ideas with Exponential-family random graph models (ERGM) which attempt to represent the complex dependencies in networks in a parsimonious, tractable and interpretable way. A major barrier to the application of such models has been lack of understanding of model behavior and a sound statistical theory to evaluate model fit. This problem has at least three aspects: the specification of realistic models; the algorithmic difficulties of the inferential methods; and the assessment of the degree to which the network structure produced by the models matches that of the data.
We will also consider latent cluster random effects models and touch upon issues of the sampling of networks and partially-observed networks.
We illustrate these methods using the “statnet” open-source software suite (http://statnet.org).

Ben Karney - Gender Differences in the Importance of Attractiveness and Weight in Established Romantic Relationships
2013-02-04 00:00
Ben Karney: University of California, Los AngelesAmong strangers, no variable has as much power to predict interpersonal judgments as physical appearance. In particular, more physically attractive people are judged as more desirable romantic partners, and generally males have been found to be more affected by a partner’s physical appearance than females. But does physical appearance continue to play a role in established relationships? We addressed this question across several studies of the early years of marriage. Drawing upon observational data on newlywed’s marital interactions, and longitudinal data on the trajectory of their marital satisfaction over time, these studies examined how the facial attractiveness of each partner (as rated by objective observers) and the body mass index (BMI) of each partner accounted for relationship processes and outcomes. In general, these results suggest that, in established relationships, the absolute level of each partner’s attractiveness matters less than the relative attractiveness of partners within the couple. Moreover, we observe consistent gender differences, such that outcomes are more favorable in couples wherein wives are more attractive than their husbands, and less favorable in couples wherein husbands are more attractive than their wives.

John Capitanio - Personality in rhesus monkeys: Some proximate, ultimate, and practical considerations.
2013-02-11 00:00
John Capitanio: University of California, DavisThere has been a growing interest in the study of animal personality, and nonhuman primate research has played a significant role in this field for many decades. My research program has focused on the causes and consequences of variation in personality dimensions in rhesus monkeys (Macaca mulatta). In this talk, I will focus on recent and current studies of prenatal and early postnatal influences on personality, some physiological mechanisms by which personality is associated with health outcomes, and implications of variation in personality for fitness-related outcomes, as well as for outcomes associated with management of captive primate colonies.

Lynn Fairbanks - Developmental Programming and Resilience in Vervet Monkeys
2013-02-25 00:00
Lynn Fairbanks: UCLAThere has been considerable interest in gestational and neonatal influences on developmental trajectories in humans and other mammals in recent years. This presentation reviews results from the Vervet Research Colony demonstrating effects of maternal condition, diet and weight loss on maternal and infant behavior. To understand the impact of variation in maternal investment on development, it is important to recognize that infants are not simply the passive recipients of variation in maternal care. Mothers and infants adjust their behavior in relationship to one another, with the mother responding to her own condition, and the infant trying to counteract attempts to limit maternal care.
Longitudinal effects of maternal condition on juvenile behavior are then examined from contrasting theoretical perspectives, including developmental canalization, fetal programming, resilience, and stress inoculation theories. Results suggest that behavioral development is largely resilient to developmental challenges within an expectable range of experience. They provide support for stress inoculation theory in that juveniles who experienced higher levels of early maternal rejection as infants became more active promoters of their own social development, while the inhibitory effects of adverse early experience on juvenile behavior were more evident under novel and challenging circumstances. The results are consistent with the view that infant and juvenile behavior evolved in the context of variation in maternal care, and selection has favored strategies for immature offspring to get what they need for physical and social development.

Barry Hewlett - Teaching, Trust, and Social Learning in Aka Forager Infancy
2013-03-04 00:00
Barry Hewlett: Washington State University, VancouverCultural anthropologists Margaret Mead, David Lancy, and Barbara Rogoff indicate that teaching does not exist or is rare in small-scale cultures. By contrast, recent research by cognitive neuroscientists Gyorgy Gergely and Gergely Csibra indicate that one type of teaching, called natural pedagogy, is a human universal, part of human nature, and not found in the great apes. They hypothesize that this form of teaching emerges in infancy and that it enhances humans’ ability to faithfully transmit “opaque” cultural knowledge, such the function of a particular tool. Learners evolved to pay attention to particular cues, such as eye and body movements, and teachers evolved the skills to convey important information to learners, such as pointing, using personal names, looking at or making sounds about important knowledge. Cognitive science research on natural pedagogy is limited because all of their studies have been conducted in laboratories with Western infants. This study uses videotapes of 10 Aka hunter-gatherer 12-14 month-old infants in naturalistic settings to evaluate the natural pedagogy hypothesis. The study shows that natural pedagogy exists in hunter-gatherers, but that it occurs relatively infrequently. The study also identifies two other forms of hunter-gatherer teaching—distributed teaching and opportunity scaffolding–that are rare or do not exist in the great apes and occur more frequently than natural pedagogy. The talk suggests that interactions between inherent evolved cognitive mechanisms, such as natural pedagogy, and culturally constructed niches of hunter-gatherers that promoted trust, enhanced social learning and made cumulative culture a distinctive feature of modern Homo sapiens.

Montserrat Soler - Rituals, Adaptions and Exaptations: Integrating Conflicting Perspectives on the Evolution of Religion
2013-03-06 00:00
Montserrat Soler: University of California, Santa BarbaraIn the last ten years, there has been a surge of work dedicated to the study of religion from the point of view of evolutionary studies and cognitive science. These accounts of religion are divided into two main areas: one views religious concepts as by-products of other cognitive capacities, while the other argues that belief and ritual are adaptations that promote intra-group cooperation. A novel way to integrate these approaches is to think of religion as a dynamic system where signalers (religious authorities) and receivers (religious followers) are engaged in a continual interaction of exploitative and cooperative strategies. Here, I will present this idea in three sections. First, I will describe how investigating the costs and benefits of religious authority and the receiver psychology of religious followers can help us understand why people believe and how those beliefs are transformed into directives for both cooperative and maladaptive behavior. Second, I will present results from an agent-based simulation model that explores the success and failure of individual signaling strategies in different conditions. In the model, different religious systems may function as risk-pooling enterprises in variable environments where leaders and followers alternate honest and dishonest signaling to compete for available resources. Finally, data from an African diasporic religion will be presented to explore the relationship between religious leadership, status and intra-group cooperation and to indicate directions for future research.

Michelle Kline - Human adaptations for teaching: A new theoretical framework and empirical tests from Fiji
2013-04-01 00:00
Michelle Kline: The University of California, Los AngelesHumans are heavily reliant on cultural adaptation, and have coevolved
with culture for millennia. Teaching enhances the fidelity of cultural
transmission and should be common in such a culture-dependent species.
However, existing data present a puzzle concerning the role of
teaching in human evolution. While biologists have documented
teaching in a number of non-human animal species, extant ethnographic
work suggests that teaching is rare in non-Western human societies.
Both sets of findings are hotly debated. I argue that disputes about
the nature and prevalence of teaching across human societies can be
resolved within an evolutionary framework that distinguishes among a
range of teaching behaviors with varying costs and benefits to
teachers and learners. This framework predicts that some teaching
behaviors should be common across societies, within particular
relationships, and for the learning of particular kinds of skills.
Here I present this new theoretical framework and confirm a number of
its predictions using two data sets from fieldwork with
fishing-horticultural villages on Yasawa Island, Fiji.

Lucia Jacobs - Chemosensory cognition and the evolution of olfaction
2013-04-08 00:00
Lucia Jacobs: University of Caliornia, BerkeleyThe chemical senses of vertebrates present some of the most enduring mysteries of brain evolution. First, it is not clear why are there two olfactory systems: the main system (MOS), detecting odorants on the olfactory epithelium and projecting to the olfactory bulb, and the accessory system (AOS), detecting odorants in the vomeronasal organ and projecting to the accessory olfactory bulb. More perplexing, taxonomic patterns of olfactory system presence and size cannot be explained by any current hypothesis, whether behavioral or phylogenetic. Yet the two systems vary immensely in structure and complexity across vertebrates, particularly in primates. Rather than assuming that the size of an olfactory system scales with the need to discriminate a class of odorants, I propose a new hypothesis: that the MOS evolved as a navigation system, to map the aqueous chemical world experienced by the early vertebrates. I further propose that this function retained its primacy in land vertebrates, and that this spatio-temporal hypothesis of olfaction offers a new explanation for the patterns of neural architecture, plasticity and allometry of olfactory systems in vertebrates.

Rich Connor - Multi-level dolphin alliances in Shark Bay
2013-04-15 00:00
Rich Connor: University of Massachusetts DartmouthFor over 25 years we have documented a multi-level alliance structure among male bottlenose dolphins in Shark Bay, Western Australia. Males cooperate in pairs and trios, ‘1st-order alliances,’ to form temporary consortships with individual females. First-order alliance partners are drawn from a male’s second-order alliance. Second-order alliances have 4-14 males and may be stable for over two decades, but occasionally lose or take in new members. First-order alliances vary in stability but this variation is not strongly related to 2nd order alliance size. Members of 2nd order alliances engage with conflicts with other groups over females, sometimes in the company of other 2nd order alliances they associate with, suggesting a 3rd alliance level. The male alliances and individual females live in an open social network where both sexes maintain their mother’s natal range as part of their adult home range. The study area can be divided into a subdivided area characterized by shallow offshore flats bisected by deeper channels and an open habitat. Trios predominate in the open habitat while pairs are common in the subdivided habitat. Further, the largest 2nd order alliances (>9) use the open habitat at least part of the year. The combination of 120 males with known alliance affiliations combined with recent technological advances presents an exciting future for studies on the development, communication, genetics and ecology of alliance formation.

Nancy Segal - Twins Raised Apart and other Unusual Pairings: Genetics, Personality and Social Relatedness
2013-04-22 00:00
Nancy Segal: California State University, FullertonAn overview of the origins, methods, findings, implications and controversies from the Minnesota Study of Twins Reared Apart is provided. This study, which took place between 1979 and 1999 at the University of Minnesota, accumulated a wealth of behavioral, physical and medical data on 137 reared apart twin pairs, 81 monozygotic (MZA) and 56 dizygotic (DZA). The focus will be on the personality and twin relationship findings, and their comparison with comparable data from an ongoing study of personality similarity and social relatedness between unrelated individuals who look alike, but are genetically unrelated (U-LAs). The U-LAs allow unique assessment of issues and questions relevant to behavioral genetic and evolutionary-based analyses. It is concluded that (1) similar treatment of MZ twins results from their shared behavioral traits, rather than their matched appearance as some critics have claimed, and (2) physical resemblance does not predict close social relations between people in the absence of perceived behavioral similarities.

Paul Heggarty - What Role for Language in Uncovering the Human Past?
2013-04-24 00:00
Paul Heggarty: 4:00 PM Cotsen Institute Room A222From the Tower of Babel to the tales of the Aboriginal Dreamtime, we have long sought to account for our baffling multiplicity of tongues. Linguistic science itself was born out of this curiosity — and by now can look to our language diversity no longer as just an enigma to be solved, but also as a rich seam of data on the human past.
Or at least potentially so, for it remains a challenge to work out exactly what the linguistic record really tells us. Certainly, it cannot safely be read without the complementary perspectives of our other windows on the past. This talk surveys how linguistics might both enrich and learn from all its sister disciplines within the original ‘four field’ foundations of anthropology, not least archaeology and population genetics. In their data-sets, methods and analyses these disciplines all differ radically, but they are only all the more complementary for it, towards their common goal of uncovering what is, after all, the same, single human past.
Early attempts were bedevilled by false analogies and simplistic associations between languages, ‘cultures’ and ‘peoples’, engendering a generalised distrust of speculations on grand cross-disciplinary synopses. So I return here to first principles, to reconsider how it is that language can inform us of the past at all. Language is a ‘social animal’; it does not ‘just happen’ that language lineages spread, interact, diverge or converge, as if in a social, cultural and demographic vacuum. Rather, those outcomes are but the linguistic reflexes of processes at work far more generally, created by and acting upon the people and societies that speak those languages. These same processes leave their imprints in material culture and the bio-archaeological and genetic records too, so it is here that the link between our disciplines lies.
To be convincing and coherent, our respective scenarios need to match independently on three key levels: when, where and why. On each, I survey the main models and methods (both traditional and new) devised for setting our language lineages into their (pre)historical contexts. I assess proposed techniques for linguistic dating, and for locating the ancestral homelands of great language families. And on causation, I peel back the distorting impacts of the modern world to explore the past roles of technologies, trade and cultural networks, state organisation, conquest, subsistence regimes, demography and environment. Any such real-world cause must also be commensurate in scale with whatever linguistic effect it is invoked to explain.
Illustrations are taken from across the millennia and across the world, from individual case-studies to the broadest patterns and contrasts in the global linguistic panorama: hotspots and ‘deserts’ of language diversity; powerful convergence areas; and vast, deep-time language families such as Indo-European or Afro-Asiatic, driven by some great expansive and divergent processes, but which? I conclude with the most ambitious generalisations of all, and the furore surrounding them: farming/language dispersals, and the claims to reduce vast proportions of all human languages into great macro-families such as the putative ‘Amerind’ of the New World.

Jennifer Hahn-Holbrook - Is Postpartum Depression a Disease of Modern Civilization?
2013-04-29 00:00
Jennifer Hahn-Holbrook: University of California, Los AngelesPostpartum depression poses an evolutionary puzzle: it is extremely common, yet significantly reduces the reproductive fitness of both mothers and children. Why has natural selection failed to remove this trait? I will consider the hypothesis that postpartum depression represents a “disease of modern civilization” – that is, a byproduct of the dramatic cultural changes to motherhood that have occurred over the last century. This perspective predicts that postpartum depression will be more common in contexts where breastfeeding, diet, exercise, sleep, & alloparenting patterns diverge most dramatically from those of our Pleistocene ancestors. I will present cross-cultural, epidemiological, and experimental studies showing that postpartum depression is associated with early weaning, insufficient vitamin D due to limited sun exposure, diets deficient in essential fatty acids, and isolation from kin support networks, all of which diverge significantly from lifestyles typical throughout most of human evolution.

Bailey House - The ontogeny of population differences in human cooperation
2013-05-06 00:00
Bailey House: University of California, Los AngelesOne explanation for the diversity in cooperative behavior across human social groups is that our prosociality is motivated in part by learned cultural beliefs that vary substantially across societies, and which extend adaptations for cooperation between genetic kin and reciprocal partners. Reframing this idea as a developmental question about how culture shapes the emergence of cooperative behavior throughout human ontogeny, in this talk I present a series of cross-cultural studies that take a first step towards understanding how population differences in cooperation emerge across human development. In these studies of prosocial behavior, I explore the origins of population differences among children aged 3-14 years in a number of diverse societies. The results of this work suggest that human prosociality unfolds through a complex interaction between developmental stages, population membership, and the personal cost of helping. These results are consistent with models of human cooperation based on evolved cultural beliefs, but they also point to critical questions that must be addressed in future work.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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

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.

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.
