Susan Perry - Social learning about foraging strategies in wild capuchin monkeys.
2008-04-28 00:00 (America/Los_Angeles)
Susan Perry: UCLA AnthropologyWhite-faced capuchin monkeys are best known for their innovation and traditions in the domain of social
communication; however, social learning appears to play a role in the acquisition of their foraging techniques
as well. In this talk, I explore several lines of evidence indicating social influence in food processing
techniques. Several foods are processed differently at different sites that are similar both genetically and
ecologically. Within social groups, those monkeys who spend more time together are also more likely to
share the same foraging technique. There is also evidence that monkeys bias their social learning
opportunities to preferentially observe models who are foraging on rare or hard-to-process foods, thus
providing useful information on what to eat and how to eat it. Developmental studies yield evidence for a
conformity bias in use of food processing techniques, even for individuals who have already learned both of
two possible techniques.

Debra Lieberman - It's all relative: Altruism, sexual aversions, and morality
2008-05-05 00:00
Debra Lieberman: U of Hawaii PsychologyMechanisms for detecting kin rely on cues that correlated with relatedness in ancestral environments to adaptively regulate mate selection and altruistic effort. For siblings, one potential cue, proposed by Edward Westermarck, is co-residence duration. Another cue that would have been highly predictive of siblingship is seeing one’s mother caring for a newborn. Data from a series of investigations show that these two cues regulate the development of altruistic motivations, sexual aversions, and, as a by-product, moral sentiments relating to incest. Revisiting the natural experiments that fueled the discussion over how sexual aversions and moral sentiments develop, I show that these two cues also explain the data from the Taiwanese minor marriages. Furthermore, I provide new evidence that childhood co-residence predicts altruistic tendencies, sexual aversions, and moral sentiments in individuals raised in the communal fashion of the Israeli Kibbutzim.

Peter Todd - Investigating mate search with simulation and speed-dating
2008-05-12 00:00
Peter Todd: U of Indiana Cognitive Science, Informatics, and Psychological and Brain SciencesThe choice of a mate is not only one of the most important decisions in our lives, but also one of the most difficult, fraught by lack of knowledge of the options to come and inability to return to options already passed by. How do we make this challenging sequential choice, at the same time we are trying to convince someone else to choose usâ€”and more specifically, how do we decide when our search is over? To find out, we could follow a set of individuals through multiple relationships over an extended period of timeâ€”or we can speed things up: We can build simulated mate-seekers who embody plausible decision rules for searching for partners, and see how they fare in an artificial mating market, comparing their behavior to that of aggregated humans. We can also speed up human mate-seekers themselves, by having them participate in speed-dating events and observing their searches as they meet and interact with a succession of potential partners. With these methods we are testing a satisfying search model that adjusts mate aspiration levels lower after failed relationships and higher after successful ones. We are also able to test other hypotheses about the kinds of mate choices people make, and how well matched they end up being.

Katie Hinde - Magnitude, Sources, and Consequences of Individual Variation in Milk Production in Rhesus Macaques
2008-05-19 00:00
Katie Hinde: UCLA AnthropologyLactation represents the greatest post-natal cost of mothering in primates and numerous studies have
established that variation in maternal condition is associated with infant growth, development, health, and
survival. Presumably the effects of maternal condition are mediated through milk output during lactation,
however this relationship remains poorly understood. Here I present the first systematic investigation of the
magnitude, sources, and consequences of individual variation in motherâ€™s milk for an Old World monkey.
Rhesus macaques produce dilute milk typical of the primate order, however there was substantial variation
between mothers, as well as within mother, over lactation in milk composition and yield, and therefore the milk
energy available for the infant. Maternal life history was associated with milk yield and milk energy density was
biased in favor of sons, especially first-born sons. Infants that had higher available milk energy at one month
of age were characterized by higher activity levels and greater confidence at 3.5 months of age suggesting that
motherâ€™s milk may serve as a nutritional cue that calibrates infant behavior and temperament to maternal
and/or environmental conditions. These results, obtained from a well-fed captive population, demonstrate that
small differences between mothers can have important implications for lactational investment and infant
outcomes.

Gyorgy Gergely - Beyond Imitative Learning: The case for Natural Pedagogy Evolutionary Mechanisms of Cultural Knowledge Transmission in Humans
2008-06-02 00:00
Gyorgy Gergely: Central European University, Budapest, Stanford Center
for Advanced Studies in Behavioral SciencesHuman minds construct cultural products that form part of the environmental niche to which new generations of human minds must adapt. A remarkable feature of cultural transmission is that infants fast-learn a vast amount of cultural skills very early on even when they cannot yet fully grasp their relevant causal, functional, intentional, or adaptive properties. This represents an apparent paradox: how can such cognitively â€˜opaqueâ€™ cultural forms be successfully transmitted and maintained across generations? Are there specialized cognitive mechanisms evolved to make efficient intergenerational transfer of such cultural knowledge possible?
The dominant view holds that it is the capacity for imitative learning that serves the evolutionary function of
cultural transmission in humans. Iâ€™ll argue, however, that presently proposed models of imitative learning face
the problem of â€˜relevance-blindnessâ€™ as they lack appropriate selection mechanisms to differentiate relevant
(to be re-enacted and learned) from non-relevant, incidental to be disregarded) aspects of observed
behaviors. â€˜Relevance-blindâ€™ imitative copying would be a wasteful and inefficient transmission mechanism
likely to lead to distorted reproduction and eventual extinction of useful cultural innovations over the
generations.
Iâ€™ll suggest that the emergence of cognitively opaque cultural skills during hominin evolution and the
consequent need for their efficient intergenerational transmission created evolutionary pressure leading to the
selection of a new type of â€˜relevance-guidedâ€™ social-communicative learning mechanism of mutual design:
the system of â€˜Natural Pedagogyâ€™ (NP) (Gergely & Csibra, 2006). On the naÃ¯ve â€œteacherâ€™sâ€ side, NP involves an
instinctual inclination to ostensively manifest – and guide the ignorant â€œlearnerâ€™sâ€ inferences to identify â€“
relevant cultural information to be fast-learned. On the naÃ¯ve â€œlearnerâ€™sâ€ side, NP involves evolved sensitivity
to â€˜ostensiveâ€™ (e.g., eye-contact, contingent reactivity, or infant-directed speech) and referential (e.g., gaze-shift
or pointing) cues that are interpreted to signal the otherâ€™s communicative intention to manifest new, relevant
(and generalizable) cultural knowledge about a referent (and its kind). Such cues trigger a receptive learning
attitude to fast-learn ostensively manifested contents even when they are cognitively opaque to the
learner. Iâ€™ll present evidence to support the NP hypothesis from our infancy studies testing the basic
assumptions of the theory about the nature of early cultural learning in humans in a number of different
knowledge domains.

Brian Skyrms - Evolution of Signaling Systems With Multiple Senders and Receivers
2008-09-29 00:00
Brian Skyrms: UC Irvine Department of Logic & Philosophy of ScienceSender-Receiver games are simple, tractable models of information transmission. They provide a basic setting for the study the evolution of meaning. It is possible to investigate not only the equilibrium structure of these games, but also the dynamics of evolution and learning â€“ with sometimes surprising results. Generalizations of the usual binary game to interactions with multiple senders, multiple receivers, or both, provide the elements of signaling networks. These can be seen as the loci of information processing, of group decisions, and of teamwork.

Russell Jackson - What You See is not What You Get: Evolved Distance Perception Adaptations
2008-10-06 00:00
Russell Jackson: CSU San Marcos Department of PsychologyDistance perception is among the most ubiquitous psychological phenomena known. Humans utilize distance estimation during all waking hours and even when sleeping. Distance perception likely takes place to this same extent in most other animals and distance perception also occurs in many non-animal species.
Furthermore, distance perception is one of the oldest researched topics in modern behavioral science. The most commonly cited founding of modern psychological science dates to Wundtâ€™s investigations of distance perception in the late 1800s. Distance perception is among the most common mental tasks and has been investigated since the founding of psychology.
Unfortunately, some of the most important questions about distance perception remain unanswered. How and why do we perceive distances the way that we do? Why is distance perception sometimes wildly inaccurate? Why are there such big individual differences in distance perception? We have yet to answer to these questions well.
Recent application of evolution by natural selection has yielded novel insights to these questions. I will discuss recent evidence from several empirical studies that discovered large magnitude visual effects, including illusions, in everyday distance perception. These illusions appear to occur constantly throughout human experiences and reach magnitudes of nearly a factor of two. These findings also illuminate a potential cause for the most prevalent, but least acknowledged, finding of all distance perception research.

Jessica Lynch Alfaro - Biological And Cultural Evolution In Capuchin Monkeys: Mapping Behavioral Traditions Onto A Cebus Molecular Phylogeny
2008-10-13 00:00
Jessica Lynch Alfaro: UCLA Center for Society and GeneticsDespite growing interest in capuchin monkeys as model organisms for social learning and cultural evolution, comparative evolutionary study of Cebus behavioral traits across field sites and species have been impeded by the lack of a robust phylogenetic hypothesis for the group. Here I present the first molecular phylogeny of Cebus and use it as a framework to study the evolution of social and foraging traditions, including anointing behaviors and tool use. Using tissue collected from museum specimens of wild-caught capuchins of known provenance across Latin America, I sequenced portions of three mtDNA genes (12s, 800 bp; cytB, 307 bp; d-loop, 435 bp) and reconstructed phylogenetic relationships using likelihood and Bayesian methods. My data revealed Cebus as a monophyletic genus composed of distinct tufted and non-tufted clades. In contrast to morphological studies, the data revealed that C. albifrons and C. libidinosis are each paraphyletic. Genetic diversity in the tufted capuchin clade was concentrated in the Atlantic forest, and the Amazonian tufted capuchins were nested as a subclade within Atlantic forest capuchins. I estimated divergence times within Cebus using external fossil calibrations under the assumption of a relaxed molecular clock and used this timetree to test whether social and foraging traditions have evolved more quickly in tufted versus non-tufted clades. This study provides both the first detailed molecular phylogeny for Cebus and new approaches to examining rates of behavioral evolution for different traits across capuchin populations. Conclusions from this study have implications for the prioritization of conservation funding and data collection.

Gary Charness - Three Field Experiments on Procrastination and Willpower / Territoriality and Gender in the Laboratory
2008-10-20 00:00
Gary Charness: UC Santa Barbara Department of EconomicsWe conducted three field experiments to investigate how people schedule and complete tasks, providing some of the first data concerning procrastination and willpower under financial incentives. In our first study, we paid students $95 if they completed 75 hours of monitored studying over a five-week period. We also required people to meet interim weekly targets in one treatment, but not in the other. In a second study, the task consisted of answering of multiple-choice questions on seven consecutive days, with staggered start dates and an endogenous task ordering (tasks varied by number of questions). In our third study, participants answered 20 multiple-choice questions over two consecutive days, varying whether this was during the week or on the weekend. Participants were required to complete an easy or difficult Stroop test (used by psychologists to deplete willpower) on the first day, before any questions could be answered. We find evidence of procrastination and willpower depletion/replenishment, as well as evidence suggesting a self-reputation interpretation. And yet the behavioral interventions we used led to outcomes that surprised us in all three studies, although these outcomes are largely consistent with the standard neo-classical model.http://www.bec.ucla.edu/Charness_Procrastination.pdf

Brooke Scelza - Bush Forager, Shop Forager: Production and Consumption Behavior in a Group of Western Desert Aborigines
2008-10-27 00:00
Brooke Scelza: UCLA Department of AnthropologyAustralian Aborigines in the Western Desert have gone through a nutritional transition in the last 50 years; moving from a diet of mainly indigenous â€œbush foodsâ€ acquired during daily foraging trips to one that includes store-bought products delivered directly to community shops. Although store-bought foods are more convenient, their availability fluctuates due to poor road conditions, community budget constraints and food spoilage. Small game and certain species of widely available large game, on the other hand, require more energy to acquire, but have a relatively consistent rate of return. An evolutionary perspective on diet choice suggests that people should make choices that will optimize their daily caloric intake and respond quickly to resource depletion. In this paper I will look at the consumption of foraged and store-bought foods in one Martu Aboriginal community to better understand issues of diet choice, foraging time allocation and risk management. I will then place this case study within a broader framework to demonstrate how an evolutionary approach can illuminate new ways of thinking about human behavior related to diet and nutrition.

John Alcock - Why I Am Still a Single-Minded Adaptationist
2008-11-03 00:00
John Alcock: Arizona State University Department of Life SciencesI will review why I became an adaptationist and continue to believe that the theory of natural selection as amended by W.D. Hamilton supplies us with all we need in order to understand all aspects of animal behavior, including that of our own species. I will examine the state of the study of animal behavior when I entered the field and the effects of the revolution that occurred around this time thanks to Hamilton and George C. Williams. I will present my take on the challenges to the “adaptationist programme” that have occurred since 1966. These challenges include Gould and Lewontin’s famous attack in the 1970s but also the current attempt to revive group selection led by David S. Wilson and E.O. Wilson. In addition, I will explain why the cultural evolution approach to human behavior has only limited usefulness. I hope to be still in one piece when I am finished.

Noah Goldstein - The Constructive, Destructive, and Reconstructive Power of Social Norms
2008-11-10 00:00
Noah Goldstein: UCLA Anderson School of ManagementSocial norms can be powerful drivers of human behavior, which means that communicators who can properly harness norms hold in their hands a powerful tool for persuasion. If utilized properly, communicators can effectively convey such norms in ways that motivate individuals to engage in positive, constructive behaviors that benefit not only those individuals themselves but society as a whole. However, even thoughtful and well meaning communicators can convey norms ineffectivelyâ€”or worse, elicit a negative, destructive backfire effect that may exacerbate an already unappealing situation. Yet, even in such instances, when a certain social norm leads individuals to perform destructive behaviors, other types of social norms can be employed to mitigate the negative influence of that norm. I will discuss how, when, and why different kinds of social norms play constructive, destructive, and even reconstructive roles in motivating human behavior.

John Mikhail - Universal Moral Grammar: Theory, Evidence, and Future Research
2008-11-17 00:00
John Mikhail: Georgetown LawScientists from various disciplines have begun to focus renewed attention on the psychology and biology of human morality. One research program that has recently gained attention is universal moral grammar (UMG). UMG seeks to describe the nature and origin of moral knowledge by using concepts and models similar to those used in Chomskyâ€™s program in linguistics. This approach is thought to provide a fruitful perspective from which to investigate moral competence from computational, ontogenetic, behavioral, physiological, and phylogenetic perspectives. In my talk, I first outline a framework for UMG and describe some of the evidence supporting it. I then discuss some initial findings of a related study in comparative law that seeks to determine how certain norms, such as the prohibition of homicide, are codified and interpreted in several hundred jurisdictions around the world. The studyâ€™s main finding, the apparent universality or near-universality of specific justifications and excuses, lends further support to UMG. It also raises novel questions for cognitive science, broadly construed, including neuroethics, behavioral economics, evolutionary psychology, and legal anthropology.http://papers.ssrn.com/abstract=1163422

Tatsuya Kameda - Emotional Functioning and Socio-Economic Uncertainty: Is "Hikikomori" an Indigenous Cultural Pathology in Japan?
2008-11-24 00:00
Tatsuya Kameda: Hokkaido University Department of Behavioral ScienceFeeling and expressing emotions appropriately in the right context is an essential component of social behavior. It has been suggested that emotional functioning has been weakened among contemporary Japanese youth, who exhibit acute social withdrawal, a “cultural pathology” known as Hikikomori (Hattori, 2005; Zielenziger, 2006). Assuming that Hikikomori is at least partially caused by socio-economic uncertainties faced by younger generations, we predicted that the syndrome is not confined to a clinical subpopulation but should be manifested by even undiagnosed youth, though in moderated form, as a negative function of their family socio-economic status (SES). Results from an emotion-sampling study â€“ in which participants’ reported their momentary emotional states 12 times per day for one-week during the course of their daily lives â€“ and a laboratory experiment â€“ which measured psycho-physiological responses to emotional stimuli â€“ both supported this prediction. Implications of these findings for the well-being of youth in well-developed, post-industrial societies are discussed.

Peter DeScioli - The Alliance Hypothesis for Human Friendship
2008-12-01 00:00
Peter DeScioli: Chapman University, Economic Science InstituteExploration of the cognitive systems underlying human friendship will be advanced by identifying the biological functions these systems perform. Here I propose that human friendship results from cognitive mechanisms designed to assemble support groups for potential conflicts. I draw on game theory to identify computations about friends that can increase performance in multi-agent conflicts. This analysis suggests that people would benefit from: 1) ranking friends, 2) hiding their friend-ranking, and 3) ranking friends according to their own position in partners’ rankings. These possible tactics motivate the hypotheses that people possess egocentric and allocentric representations of the social world, that people are motivated to conceal this information, and that egocentric friend-ranking is determined by allocentric representations of partners’ friend-rankings (more than others’ traits). I report several investigations designed to test predictions derived from these hypotheses. The results suggest that the alliance hypothesis merits further attention as a candidate explanation for human friendship.

Caleb Finch - The Role of Diet and Infection in Human Evolution
2009-01-05 00:00
Caleb Finch: USC Davis School of GerontologyHuman lifespans have increased remarkably from the 20 year life expectancy (LE) of the great apes. The normative 40 y LE of pre-industrial peoples has recently risen to about 80 y in privileged populations during the last 200 years. I propose that diet and infections are key to understanding both demographic transitions. During human evolution, human ancestors shifted from a largely plant based diet to include larger amounts of animal tissues and cholesterol intake that observed in the extant great apes. Exposure to infections also increased because of consumption of raw tissues and from close contact with feces not observed in great apes which rarely use the same night nest. In 2004, Craig Stanford and I hypothesized that “meat-adaptive genes” enabled these transitions (Q Rev Biol. vol 79, 2004). Apolipoprotein E is a candidate for pleiotropic genes with influences on blood lipids, innate immunity, and brain development; the apoE3 allele that increases LE spread in human populations about 225,000 years ago. I will further discuss the possible role of apoE alleles and other genes in supporting the recent increase in LE during post 18th century improvements of diet and reduction of infections.

Karthik Panchanathan - Quantifying the Bystander Effect in a Multi-Player Dictator Game
2009-01-12 00:00
Karthik Panchanathan: UCLA Department of AnthropologyBehavioral economics studies have shown people to have other-regarding social preferences. In the Dictator Game, for example, dictators transfer some portion of their endowment to recipients, who start out without an endowment. If people were self-interested, those assigned the role of dictator would keep all of their endowment; those assigned to be recipients would go home with nothing. In social psychology, scores of studies document the Bystander Effect, in which the likelihood of receiving help declines as the number of potential helpers increases. To reconcile pro-social preferences with the Bystander Effect, psychologists propose the notion of diffusion of responsibility: while people want to see the victim helped, they feel less of a responsibility to help when others are present and able to help. Here, we present results from two multi-player dictator games, one in the lab with real stakes (N=196) and one online with hypothetical stakes (N=215), to look for evidence of the diffusion of responsibility in an experimental economics setting.

James Fowler - Genes and Social Networks
2009-01-26 00:00
James Fowler: UCSD Political Science DepartmentSocial networks exhibit strikingly systematic patterns across a wide range of human contexts. While genetic variation accounts for a significant portion of the variation in many complex social behaviors, the heritability of egocentric social network attributes is unknown. Here we show that three of these attributes (in-degree, transitivity, and centrality) are heritable. We then develop a “mirror network” method to test extant network models and show that none accounts for observed genetic variation in human social networks. We propose an alternative “Attract and Introduce” model with two simple forms of heterogeneity that generates significant heritability as well as other important network features. We show that the model is well suited to real social networks in humans. These results suggest that natural selection may have played a role in the evolution of social networks. They also suggest that modeling intrinsic variation in network attributes may be important for understanding the way genes affect human behaviors and the way these behaviors spread from person to person.http://arxiv.org/abs/0807.3089

Nathan Bailey - Same-sex Mating Behavior and Evolution
2009-02-02 00:00
Nathan Bailey: UC Riverside Department of BiologySame-sex mating behavior has been extensively documented in non-human animals, but we still know relatively little about its evolutionary impact. What evidence exists that same-sex sexual behavior can be adaptive? Do the genetic and physiological mechanisms underlying same-sex mating help explain its ultimate cause and maintenance in populations? How flexible is it, and what is the significance of that plasticity? And can same-sex mating interactions influence the evolutionary dynamics of populations? My talk will draw upon studies published in the last several years in a wide variety of non-human animals to highlight discoveries addressing the role of same-sex sexual behaviors as agents of evolutionary change. I will focus on both the evolutionary causes and consequences of same-sex mating behavior. However, the bulk of the discussion will be organized around the second theme, because recent studies suggest that the impact of same-sex mating behavior on population-level processes can be powerful and of considerable importance.

Robert Boyd - The Evolution of Social Stratification
2009-02-09 00:00
Robert Boyd: UCLA Department of AnthropologyIn this talk I explain how culturally heritable differences in wealth between social groups can arise and be maintained even when the only adaptive learning process driving cultural evolution increases individuals’ economic gains. The key assumptions are that human populations are structured into groups and that cultural learning is more likely to occur within groups than between groups. Then, if groups are sufficiently isolated and there are potential gains from specialization and exchange, stable stratification can sometimes result. This model predicts that stratification is favored by (1) greater surplus production, (2) more equitable divisions of the surplus among specialists, (3) greater cultural isolation among subpopulations within a society, and (4) more weight given to economic success by cultural learners. I will conclude by arguing that this mechanism may explain why there is much more heritable variation among groups within the human species than in other taxa.http://www.sscnet.ucla.edu/anthro/faculty/boyd/HenrichBoydCA0908.pdf

David Sloan Wilson - Evolving the City: Using Evolutionary Theory to Understand and Improve the Quality of Everyday Life
2009-02-17 00:00
David Sloan Wilson: SUNY Binghamton Department of Biological
Sciences & Department of AnthropologyEvolutionary theory is rapidly expanding beyond the biological sciences to include all human-related subjects in academia. Since evolution is fundamentally about organisms in relation to their environment, basic scientific research needs to focus on people from all walks of life, as they go about their daily lives. This kind of research is also most relevant for improving the quality of everyday life, leading to a positive tradeoff between basic and applied science. I will provide an overview of The Binghamton Neighborhood Project, a unique “whole university/whole city” approach to community-based research from an evolutionary perspective.

Daniel Nettle - Why is the Theory of Evolution So Hard to Understand?
2009-02-23 00:00
Daniel Nettle: Newcastle University Centre for Behaviour and EvolutionEven in the most developed countries, many people do not accept the theory of evolution as true. Whilst there are cultural and ideological reasons for this, part of the issue is that evolutionary ideas appear to violate certain intuitive beliefs. Even more interestingly, recent research has shown that students who do accept evolution quite systematically misunderstand how it works, tending to endorse species selectionism, the idea that species are born and die abruptly, and models of heredity in which useful characteristics are acquired by all members of the species, not just the progeny of the individuals in which they arise. I will argue that all of these errors arise because in our intuitive cognition about animals, there is little distinction between the species and the individual. Indeed, species are seen as a kind of individual, and individual animals are seen as appearances of the underlying species. This leads people into what Ernst Mayr called typological, rather than population, thinking. I report results of a recent study of conceptualisation of evolutionary change amongst undergraduate students, and argue that a good way of conveying evolutionary ideas is by using human examples, since our intuitive cognition about humans primarily works at the level of individuals, their family relationships, and the ways they are different from other members of their species.

Patricia Gowaty - It's About Time: Reproductive Decisions Under Ecological and Fitness Constraints
2009-03-02 00:00
Patricia Gowaty: UCLA Department of Ecology and Evolutionary BehaviorDo genes for choosy females and indiscriminate mates determine typical sex roles; or, do ecological and social constraints determine sex roles? Or is sex role determination due to more complex interactions of sex-associated genes and ecological conditions? Answering this question has been difficult, largely because until now there has been no null theory of ecological constraints on sex-associated “sex role” behavior. Here we describe the switchpoint theorem (SPT) that analytically solves the problem of what fraction of potential mates in a population a focal individual of either sex should find acceptable to mate in order to maximize relative lifetime fitness; the SPT is a null model of ecological constraints on reproductive decision-making. The SPT assumes that demographic stochasticity affects time available for mating and that there is variation in fitness that would be conferred by mating with alternative potential mates, to prove that environmental induction of flexible, reproductive decision-making of individuals of both sexes is adaptive. The SPT provides a reasonable scenario for the assumption that all individuals assess likely fitness outcomes before accepting or rejecting a potential mate. Rather than assuming sex differences in genes for choosy females and indiscriminate males, the SPT is a sex-neutral hypothesis that begins with individual differences in ecological constraints to predict induced and adaptive sex role variation. The predictions of the SPT depend on five parameters: individual survival and encounter probabilities, population size, the distribution of fitness that would be conferred by mating with alternative potential mates, and individual latencies (time outs after copulation). The SPT predicts that all else equal, higher probabilities of individual survival and encounters, higher population sizes, and longer latencies decrease the fraction of acceptable mates for focal individuals, so that focal individuals reject more potential mates. Similarly, it predicts that when instantaneous survival and encounter probabilities decline, adaptively flexible individuals accept more potential mates. The SPT provides a novel, quantitative, unified framework for studying how sexual selection and sexual conflict may operate when individuals manipulate the time available for mating of potential mates, their mates, and rivals.

Rebecca Bliege Bird - Why Women Hunt: Risk and Contemporary Foraging in a Western Desert Aboriginal Community
2009-03-09 00:00
Rebecca Bliege Bird: Stanford University Department of AnthropologyAnthropologists commonly invoke an “economy of scale” to explain gender differences in hunter-gatherer subsistence and economic production: wives pursue childcare-compatible tasks and husbands, of necessity, provision wives and offspring with hunted meat. This theory explains little about the division of labor among the Australian Martu, where women hunt extensively, and gendered asymmetry in foraging decisions is linked to men’s and women’s different social strategies. Women cooperate with other women primarily hunt small, predictable game (lizards) to provision small kin networks, to feed children, and to maintain their cooperative relationships with other women. They trade off large harvests against greater certainty. Men tend to hunt as a political strategy, using a form of “competitive magnanimity” to rise in the ritual hierarchy and demonstrate their capacity to keep sacred knowledge. Resources that can provision the most others with the most meat best fit this strategy, resulting in an emphasis on kangaroo. They trade off reliable consumption benefits to the nuclear family for more unpredictable benefits in social standing. Among the Martu, gender differences in the costs and benefits of engaging in competitive magnanimity, rather than an economy of scale, structure men’s more risk-prone and women’s more risk-averse foraging decisions. These results suggest an alternative model of the foraging division of labor that emphasizes the role of ecological variance and social competition and de-emphasizes essentialized sexual and reproductive dichotomies.

Roberto Delgado - Revisiting Island Differences in Orangutan Socioecology: Behavioral Flexibility and Geographic Variation
2009-03-30 00:00
Roberto Delgado: USC Department of AnthropologyInitial field observations and reports from a few short-term studies pointed to island differences between Bornean and Sumatran orangutans in their general appearance and behavioral ecology, implying meaningful taxonomic distinctions. However, upon further scrutiny at multiple sites and for longer periods of study, researchers have found population-specific differences across a wide array of features including dietary breadth, foraging strategies, life history parameters, molecular markers, morphological characters, reproductive tactics, sociality, tool-using abilities, vocalizations and other traits. Furthermore, the nature of this variation is not always in line with expectations based on a simple island (i.e. Borneo vs. Sumatra) dichotomy, making suspect previous assumptions about historical divergence patterns. Herewith, I review the extent of qualitative and quantitative differences documented and explore a theoretical framework for examining geographic variation and behavioral flexibility among orangutan populations. In particular, I address hypotheses invoking genetic differences, anatomical differences, ecological factors and opportunities for social learning to explain population-level differences. The available data to date suggest that differences in habitat productivity with its concomitant effects on demographic factors such as local population density can influence patterns of gregariousness as well as both the frequency and intensity of social learning within orangutan communities. By examining the occurrence and distribution of geographically varying characteristics such as subsistence skills, comfort skills, and signals, we can determine whether or not the observed patterns of variation are justified with a cultural interpretation when other (i.e. ecological, genetic) explanations are not adequate. Hence, identifying the underlying factors leading to geographic variation in behavior has implications for understanding the emergence of local traditions among great apes as well as the origins and evolution of culture within the human lineage.

Joseph Henrich - The Evolution of Cultural Adaptations: Fijian Food Taboos Protect Against Dangerous Marine Toxins
2009-04-06 00:00
Joseph Henrich: University of British Columbia Departments of Psychology and EconomicsThis talk will first develop an evolutionarily-informed, cognitively-grounded approach to culture, and then apply this approach to explain patterns of food taboos for pregnant and lactating women on Yasawa Island, Fiji. Within a broader cognitive framework, I focus on (1) understanding our capacities for cultural learning as evolved cognitive mechanisms for acquiring adaptive information from other individuals, in a complex, noisy, and changing world, and (2) examining how and when these learning mechanisms result in cumulative cultural evolutionary processes that produce population-level patterns of adaptation and maladaptation. Then, applying this framework, I will argue that the patterns of food taboos observed across three villages in Fiji represent a culturally-evolved adaptation, influenced by various cognitive biases, that protects women, fetuses, and infants from dangerous marine toxins. Our findings indicate that these patterns likely emerged, and are now maintained, by the operation of the cultural learning mechanisms predicted by our evolutionary approach to cognition.

Naomi Eisenberger - Why Rejection Hurts: Examining the Shared Mechanisms Underlying Physical and Social Pain
2009-04-13 00:00
Naomi Eisenberger: UCLA Department of PsychologyNumerous languages characterize â€˜social pain,â€™ the feelings resulting from social rejection or loss, with words typically reserved for describing physical pain (â€œbroken hearts,â€ â€œhurt feelingsâ€) and perhaps for good reason. It has been suggested that, in mammalian species, the social attachment system borrowed the computations of the physical pain system in order to prevent the potentially harmful consequences of social separation. In this talk, I will use a combination of behavioral and neuroimaging methodologies to explore the notion that physical and social pain rely on overlapping neural and experiential processes. Specifically, I will examine: 1) whether social pain activates pain-related neural circuitry, 2) whether individual differences in sensitivity to one kind of pain relate to individual differences in sensitivity to the other (e.g. Are individuals who are more sensitive to physical pain also more sensitive to social pain?), and 3) whether factors that up- or down-regulate one type of pain affect the other in a similar manner (e.g., Can physical painkillers reduce social pain?).

Barbara KÃ¶nig - Cooperation and Social Selection - A Case Study of Communal Nursing in House Mice
2009-04-15 00:00
Barbara KÃ¶nig: University of Zurich Institute of ZoologyIn addition to sexual selection, selection resulting from social interactions in contexts other than mating can be a potent evolutionary force. Such social selection processes are facilitated whenever individual fitness varies as a result of any form of social interactions. The choice of social partners for communal care of young is such a situation in which interactants potentially experience fitness variance. We combine lab experiments with field data to investigate the existence and impact of female social partner choice and the potential for social selection to occur in the communally breeding wild house mouse (Mus domesticus). Female house mice display non-random preferences, and social partner choice yields significant fitness benefits. This suggests that interactions among females are subject to social selection processes, driving the evolution of female traits.http://www.bec.ucla.edu/Konig.pdf

Edouard Machery - Did Morality Really Evolve?
2009-04-20 00:00
Edouard Machery: University of Pittsburgh Department of History and Philosophy of ScienceThat morality evolved is a commonplace among evolutionary biologists, psychologists, and anthropologists. In this talk, I will however argue that biologists, psychologists, and anthropologists have failed to pay enough attention to the differences between three distinct interpretations of the hypothesis that morality evolved: (1) some components of moral cognition (e.g., some particular emotions, concepts, or norms) evolved, (2) a capacity to grasp and be motivated by norms in general evolved, and (3) a capacity to grasp and be motivated by a distinctive type of norms evolved. Under the first two interpretations, it is fairly uncontroversial that morality evolved, while under the third and most interesting interpretation, the hypothesis that morality evolved is empirically unsupported. Philosophical implications in ethics will be incidentally considered.http://www.bec.ucla.edu/MacheryEvolutionOfMorality.pdf

Jenessa Shapiro - Perceiving White Norms: Ironic Effects in Blacks' versus Whites' Judgments of Minority Targets
2009-04-27 00:00
Jenessa Shapiro: UCLA Department of PsychologyConformity to a perceived norm is a common strategy used to gain the approval of one’s interaction partners. Identifying a group norm is ordinarily relatively simple. However, this task may be especially difficult when the norm is held by a group to which one does not belong, as is the case in intergroup interactions. In contemporary American society, Whites tend to believe that norms condemning public expressions of racial prejudices are pervasive (e.g., Dovidio & Gaertner, 1986). In contrast, Black Americans tend to view normative White behavior as prejudicial against themselves and other minority groups (e.g., Neimann, Jennings, Rozelle, Baxter, & Sullivan, 1994). The present research examined some ironic implications of this divergent perception of White prejudice-relevant norms. In one study, when evaluations of a Native American job candidate were to be made public to an unfamiliar group of White males upon whom participants were dependent, White men expressed less prejudice whereas Black men expressed greater prejudice, relative to when these responses remained private. In contrast, White and Black females expressed no prejudice when their evaluations were to be public to White females, although Black females expressed generally more favorable judgments of both White and Native American candidates. Follow-up studies support the hypothesis that differential inferences about White prejudice norms underlie this pattern of findings: The public judgments made by Black males (compensatory conformity) and Black females (compensatory pleasantness) can be seen as strategies aimed at reducing the likelihood that they themselves will be discriminated against in an intergroup interaction.
