Center for Behavior, Evolution, and Culture

Ádám Miklósi - Dog-human social interaction: Old wine in new bottles?
2011-02-25 00:00 (America/Los_Angeles)
Ádám Miklósi: Eötvös University Department of EthologyFor longer than we can remember dogs and humans have been friends. While both humanity and dogs benefited from this relationship, science has not shown any interest in the “Whys” and “How-s” until recently. However, the last 15 years have pushed the dog into the middle ground
of comparative investigations that aim to understand the evolution and mechanisms of social behavior.
In this presentation I will present a simple descriptive model for convergent
behavioral evolution of dog social behavior in the anthropogenic environment. The central
example will describe how in a very simple way dogs may have adapted to the pedagogical
nature of humans. We have good experimental evidence that dogs can be attracted to human
communicative intent, to human referential signals, and may learn about the referent. Parallel
work has shown that this ability shows strong parallels to early pedagogical interaction
between human infants and caregivers but rests probably on different mechanisms. In any
case, the dogs’ receptiveness to human social signals enhances their survival in our social
niche.
Based on these findings we can put forward a more general model of social behavior in the
case of inter-specific relationships, introducing the concept of social competence. It turns out that
this may be particularly useful in recent research which is aimed to envisage a “new world” of
human-artificial agent social interaction.
http://bec.ucla.edu/papers/MiklosiPaper.pdf

Brian Wood - Household and Kin Provisioning by Hadza Males
2011-02-14 00:00
Brian Wood: Stanford Department of AnthropologyIn this research, we use newly collected data describing how Hadza men’s foods were produced, shared, and consumed in order to elucidate the general motivations underlying, and consequences of, Hadza male foraging strategies. We test predictions of the showoff, costly signaling, household provisioning, and kin provisioning hypotheses, finding strong support for the latter two. We find that Hadza men foraged for a range of food-types, including fruit, honey, small game, and large game. Our data indicate that men shared the foods they produced in ways that directly benefitted their own households as well as their consaguineal and affinal kin living in other households. Our work indicates that large game hunting was one important element of men’s foraging strategies but not an exclusive specialization. These results differ from prior investigations of the Hadza, in which it was argued that men specialized in hunting large game for its status benefits, rather than pursuing other types of foods and more effectively feeding their households. We discuss how and perhaps why our studies differ. We also explore how camp demographics, seasonality, and men’s marital status influenced their food production and sharing.

Derek E. Lyons - The social roots of artifact culture: Overimitation and the development of children’s causal understanding
2011-02-07 00:00
Derek E. Lyons: Post-Doctoral Scholar; UC Irvine Department of InformaticsChildren are generally masterful imitators, both rational and flexible in their acquisition of knowledge from the observation of others. A phenomenon that we have termed overimitation (Lyons, Young, & Keil, 2007), however, initially seems a curious exception to this rule. After observing an adult intentionally operating an unfamiliar object with a sequence of relevant and irrelevant actions, children will frequently imitate not only the actions that were causally necessary, but also those that were clearly superfluous. Indeed, children will overimitate irrelevant actions that even chimpanzees readily ignore (Horner & Whiten, 2005). Prior explanations for overimitation tended to see it as a byproduct of social motivations (e.g. a desire to “be like” the adult or to accommodate inferred task demands), but we have argued that the phenomenon may have deeper significance. Our hypothesis is that when children observe an adult intentionally acting on a novel object, they may automatically encode all of the adult’s actions as causally meaningful, restructuring their causal beliefs about the object accordingly. This process of automatic causal encoding (ACE) would generally guide children to accurate beliefs about even highly opaque objects; however, in the case where some of the adults’ intentional actions were unnecessary, it would also lead to stubborn overimitation. In this talk I will undertake a thorough examination of the ACE hypothesis, reviewing prior evidence as well as offering three new experiments to further test the theory. Our new data show that children will persist in overimitating even when doing so imposes a direct and motivationally salient cost, thus underscoring the involuntary nature of the effect. At the same time, however, overimitation is not unbounded: the effect is strictly coupled to intentionality in a manner consistent with its posited learning function. Overimitation may offer an important window not only on the structure of children’s causal understanding, but also on the social learning processes that help to support our species’ artifact-centric culture.

Sarah Mathew - Warfare and the collective action problem in acephalous societies
2011-01-31 00:00
Sarah Mathew: UCLA Department of AnthropologyKnowledge of the nature and scale of cooperation in acephalous societies is important for understanding the evolution of human sociality. I will present data showing that the Turkana, an acephalous pastoral society in East Africa, sustain costly large scale cooperation in warfare through informal sanctions against free riders, and that Turkana norms regulating warfare benefit the ethno-linguistic group, not smaller social units. The findings shed light on the equilibrium selection processes that have shaped human sociality and suggest that large scale cooperation may have been common for a long period of human evolutionary history.

Jason A. Clark - Serial homologies of psychological traits: the case of emotions
2011-01-24 00:00
Jason A. Clark: University of Osnabrueck Institute for Cognitive ScienceWithin emotion theory, it is common for theorists to order emotions along phylogenetic and developmental scales. ‘Basic emotions’ (such as fear and joy) are seen as having a longer evolutionary history that we share with other animals, and as emerging earlier in development. Higher-cognitive emotions (such as shame and pride) are often seen as arising de novo in the human line, and late in development, and both their evolution and development are seen as arising from uniquely human higher-cognitive capacities.
However, an increasing number of emotion theorists are converging on the idea that higher-cognitive emotions in humans are homologous to simpler forms of these emotions in nonhuman animals, and branch off from developmentally earlier and simpler precursors. One problem faced by such theories is the fact that the more basic forms of emotions appear to persist as such, despite the emergence of higher-cognitive forms. This is inconsistent with the standard view of homology according to which ancestral traits are transformed into derived traits in a continuous series in which the original form of the trait is lost or modified.
One solution to this problem which reconciles evolutionary and developmental transformations with the persistence of the original forms is to construe these homologies as serial homologies. In serial homology a trait is duplicated, and while the original trait usually remains in place and functions as before, the duplicate trait is allowed to vary independently in response to potentially distinct evolutionary pressures. According to this model, ancestral ‘basic’ forms of emotions (or some of their components) are duplicated. The basic forms of these emotions are retained, while the duplicates are allowed to vary within uniquely human evolutionary, cultural and cognitive contexts. This thesis is illustrated using a variety of emotions, including shame, pride, disgust, and laughter. Finally, while serial homologies are often invoked to explain behaviors, they are not typically applied directly to psychological capacities. I consider some of the general issues involved in such applications, including some potential brain mechanisms that might underlie them.

Bruce Winterhalder - Behavioral ecology models of habitat in-fill and the evolution of prehistoric despotism
2011-01-10 00:00
Bruce Winterhalder: UC Davis Anthropology & Graduate Group in EcologyMy topic is the evolution of despotism and oligarchies in prehistoric societies. I begin by covering ground that is theoretically well understood, the novelty rests in the empirical analysis and methods. Prehistoric settlement of the Northern Channel Islands (Santa Barbara) follows a pattern predicted by the Ideal Free Distribution (IFD). I establish this by comparing the resource suitability of 46 watersheds to a well-studied archaeological record using a Gibbs sampler to assess model fit. As population on the islands grew, habitat quality in settled sites declined and sites of decreasing desirability were colonized. The second part of the talk is more theoretical and speculative. Reproductive skew models make the prediction that opportunities for socio-economic exploitation would expand concurrently with habitat in-fill. This hypothesis is consistent with the archaeological data, in that Late Prehistoric Chumash residents of the region were characterized by hereditary chiefdoms, wide-ranging economic exchange, declines in stature and endemic conflict. But, it is not yet well understood in model form. Acknowledging the influences of both Boserup and Carneiro, I conclude by describing briefly our effort to develop population ecology models focused directly on the evolution of despotism.papers/WinterhalderPaper1.pdf

Moshe Hoffman - Biological Basis of Sex Differences in Risk Aversion and Competitiveness
2011-01-03 00:00
Moshe Hoffman: UCSD Rady School of ManagementWe review the evidence regarding a biological basis for sex differences in risk aversion and competitiveness. We present the relevant literature in evolutionary theory, and animal behavior, endocrinology and neuroscience, as well as the literature relating human risk aversion and competitiveness to handedness, 2D:4D (a proxy of prenatal testosterone exposure), facial masculinity (a proxy of pubertal testosterone exposure), as well as circulating testosterone. While the results are thus far somewhat mixed, the evidence suggests that biological factors explain part of the sex gap in these economic preferences.http://bec.ucla.edu/papers/HoffmanPaper1.pdf

Christophe Boesch - Ecology of Cooperation and Altruism in Humans and Chimpanzees
2010-12-08 00:00
Christophe Boesch: Director of the Department of Primatology at the Max Planck Institute for Evolutionary AnthropologyFieldwork studies have revealed with much detail the sophisticated levels of cooperation and altruism in the social domain seen in many animal species. Now, recently some psychologists and economists are loudly claiming that cooperation and altruism are uniquely human abilities. How can such divergences originate? In my eyes, a very strong underestimation of ecology is at the origin of such a situation. I review in my talk some of the recent evidence showing the importance of ecology on the development of intelligence in humans and in chimpanzees and how that affects the performance of cooperation and altruism in these two species. The evolution of cooperation and altruism is decisively affected by the ecological conditions and this explains why under some contexts the level of cooperation and altruism might strongly differ within one species. In conclusion, I ask for more sensitivity to ecological conditions when making cross- species comparisons and suggest that at present no data support a species difference in cooperation and altruism tendency, but all point to a strong ecological component.

Jennifer Smith - Kinship structures patterns of cooperation and social network dynamics in the spotted hyena
2010-11-29 00:00
Jennifer Smith: UCLA Center for Society & Genetics and Department of Ecology and Evolutionary BiologyCooperation is pervasive in the societies of humans and other animals, yet the current body of evolutionary theory often fails to fully explain its persistence. Because spotted hyenas (Crocuta crocuta) live in complex societies, this species provides an interesting opportunity to elucidate the evolutionary forces favoring patterns of cooperation in a group-living carnivore. Unlike most social carnivores, which live only with their kin, hyenas reside in social groups, called ‘clans’, comprised of both kin and non-kin. In fact, hyena clans are strikingly similar in their size and hierarchical structure to troops of Old World monkeys. Like groups of humans and other apes, hyena societies are further structured by fission-fusion dynamics. That is, individual hyenas regularly separate from and rejoin members of their permanent social group on an hour-to-hour basis. Here, I apply social network theory to analyze the effects of kinship and resource distribution on the social relationships among these ‘primate-like’ carnivores. This work is part of a long-term study in the Masai Mara, Kenya. The results indicate that hyenas associate most often with their kin, and that although resource competition constrains the strength of social network ties among all hyenas, kin always sustain the strongest relationships. Moreover, when forming coalitions, hyenas bias agonistic support towards kin and take the greatest risks when helping kin. Finally, I show that hyenas regularly reinforce social ties with kin, and closely associating non-kin, through ritualized reunion displays, called greetings. Overall, this work reveals the central role of kinship and signaling in the maintenance and coordination of cooperation among social allies living in dispersed social groups.http://bec.ucla.edu/papers/JenSmithPaper1.pdfhttp://bec.ucla.edu/papers/JenSmithPaper2.pdfhttp://bec.ucla.edu/papers/JenSmithPaper3.pdfhttp://bec.ucla.edu/posters/JenSmithPaper4.pdf

Parry Clarke - Infanticide and Reproductive Restraint in the Archetypical Polygynous Primate
2010-11-22 00:00
Parry Clarke: UC Davis Department of AnthropologyClassic sexual selection theory, exemplified by the work of Bateman and Trivers, has played and continues to play a central role in the study of primate mating systems. As a result, most theorizing within the field is premised on the assumption that males have been selected to maximize competitive ability at the point of conception and are largely immune to variance in infant survivorship. This perspective runs contrary to more recent theoretical treatments of sexual selection, however, which point out that males will rarely, if ever, be able to compensate for infant mortality through re-mating and should therefore be sensitive to infant survivorship. Using data on male reproductive success in wild chacma baboons (Papio hamadryas ursinus) I will argue that males do act to augment their offspring’s survivorship and they do so at the expense of their maximum potential reproductive output. Specifically, I will show data suggesting that dominant males willingly cede reproductive opportunities to subordinates in an effort to encourage them to remain in the group. I conclude that this is because by doing so they afford their infants a greater level of protection from infanticide, a significant source of infant mortality in chacma.

Dominic Johnson - Adaptive Politics: The Strategic Advantages of Psychological Biases
2010-11-15 00:00
Dominic Johnson: University of Edinburgh Reader in Politics & International RelationsA recent explosion of work suggests a key role for human physiology and evolutionary psychology in understanding political behaviour, from genes to hormones to cognition. However, the entire notion of an evolutionary basis for human behavior meets a traditional skepticism in the social sciences, and political science in particular. One common conception is that psychological biases are “mistakes” or “errors” that cause policy failures, disasters, or wars. The book sets out the argument that psychological biases have their roots in the evolution and biology of the human brain. Consequently, they are far from “mistakes”, but rather they are adaptive heuristics that were favoured by natural selection because they brought important advantages in our evolutionary past. The question that remains is whether (and when) they continue to be triggered in appropriate contexts today. Given the social and political differences between the environment of our past and the environment of today (mismatch), an evolutionary approach offers fresh predictions for when, why and how psychological biases will worsen, or at other times improve, contemporary political decision-making. The book examines five common psychological phenomena that have commonly been used to explain decision-making failures in political science: (1) overconfidence, (2) cognitive dissonance, (3) the fundamental attribution error, (4) prospect theory, and (5) in-group/out-group bias. It is argued that all of them can equally be adaptive rather than maladaptive in some contexts. The idea is that in doing so, political scientists will be forced to rethink whether biases may have a functional rather than destructive role, implying an evolutionary origin. The book is intended to be provocative, showing that false beliefs can paradoxically lead to more effective decision-making–”just as they were “designed” to do by natural selection. But effectiveness depends on context, because behavioral mechanisms are contingent, not fixed. An evolutionary approach therefore offers us the tools to improve our understanding and predictions of political phenomena.

Michael Alvard - Social structure, cultural kinship, and cooperation among the Lamalera whale hunters of Indonesia
2010-11-08 00:00
Michael Alvard: Texas A&M University Department of AnthropologyThe human ability to form large, coordinated groups is among our most impressive social adaptation. Larger groups facilitate synergistic economies of scale for cooperative breeding, economic tasks like group hunting, and success in conflict with other groups. In many organisms, genetic relationships provide the structure for sociality to evolve via the process of kin selection, and this is the case, to a certain extent, for humans. But assortment by genetic affiliation is not the only mechanism that can bring like-minded people together. Affinity based on symbolically mediated and socially constructed identity or cultural kinship structures much of human sociality.
This talk will examine how genetic kinship and various kinds of cultural kinship–affinal, descent, moiety–structure the network of cooperating whale hunters in the village of Lamalera, Indonesia. The people of Lamalera are among the last subsistence whale hunters on the planet. The village of 1,200 people rely largely on the sperm whales, other marine mammals, manta and other rays that the community’s men cooperatively hunt from a fleet of traditional, 11m long, whaling vessels called tèna.
Using data from 853 hunts, network analyses show that each mechanism of assortment produces characteristic networks of different sizes, each more or less conducive to the task of hunting whales. The results are discussed in the context of the evolution of cooperation and group identity.

James Holland Jones - Contact Networks, Models of Infectious Disease, and Epidemic Simulation
2010-11-01 00:00
James Holland Jones: Stanford University Department of AnthropologyInteraction networks shaped by social processes constitute the substrate on which various phenomena of interest to evolutionary anthropologists and human biologists occur. Examples of such phenomena include epidemics, diffusion of ideas or information, and the exertion of social and political influence. Understanding the structure of network formation is thus crucial to our understanding of how relational human interactions mediate key biosocial outcomes. Research in this area has been hampered by an acute lack of (1) high-quality data on the formation and structure of contact networks and (2) realistic models for the social processes that shape networks. In this talk, I present results from two recent papers that address these deficits. First, I will show the consequences for epidemic behavior of networks that exhibit strong community structure. Such hierarchical social interaction is ubiquitous in human populations, making it important that we understand the behavior of epidemics in community-structured networks. We show that the degree of community structure has a pronounced impact on the final size of simulated epidemics, even in the absence of any changes in the basic reproduction number of the epidemic. We use our results to design network-informed vaccination strategies that generally outperform comparable existing strategies.
Our finding that community structure can affect epidemic behavior qualitatively highlighted the acute lack of high-quality data on network structure for relations relevant to disease transmission and motivated our collection of such data. Using Wireless Sensor Network (WSN) technology, we measured the temporal dynamics of close-proximity interaction networks during a typical school day in a high school in the San Francisco Bay Area. Participants wore small wireless sensors which send and receive radio signals to and from other sensors nearby. This technology allowed us to collect dynamic contact network data with unparalleled precision. At a 94% coverage, we collected 762,868 CPIs at a maximal distance of 3 meters among 788 individuals. The data revealed a high density network with typical small world properties and a relatively homogenous distribution of both interaction time and interaction partners among subjects. Computer simulations of the spread of an influenza-like disease on the weighted contact graph are in good agreement with absentee data during the most recent influenza season. Analysis of targeted immunization strategies suggested that contact network data are required to design strategies that are significantly more effective than random immunization. Immunization strategies based on contact strength were generally most effective and the effects were seen most acutely at high vaccination coverage.

Robert Wayne - Evolution and diversification of the domestic dog
2010-10-25 00:00
Robert Wayne: UCLA Department of Ecology and Evolutionary BiologyThe domestic dog is one of our most remarkable inventions. The behavioral and functional diversity of the dog far surpasses that of its wild progenitor, the gray wolf. Similarly, in size and proportion, dogs exceed the diversity of the entire carnivore order. The dog genome project and recent advances in biotechnology have enabled a new understanding of the process of domestication and diversification. I discuss our recent molecular findings concerning the origin of the dog and present a new evolutionary tree of dogs that leads to a better understanding of the nature of artificial selection and how it has shaped the diversity of our closest animal companion.
*(Co-Sponsored by the UCLA Center for Society and Genetics)

Thomas Flamson - Encryption Theory: The evolution of humor as an honest signal
2010-10-18 00:00
Thomas Flamson: Santa Monica College Department of Earth Science / UCLA Department of AnthropologyThe Encryption Theory of Humor proposes that humor evolved as a means of signaling similarity in locally variable personal features in order to facilitate assortment with the most compatible peers within the local group. It claims that a necessary component of humorous production is the presence of multiple, divergent understandings of speaker meaning, some of which are dependent on access to implicit information. Because of this dependence, only those listeners with access to this background knowledge can “decrypt” the implicit understandings, which further entails the inference that the speaker shares that access. This provides a channel for the honest signaling of personal features, which enables within-group assortment for compatible long-term interaction partners such as friends or mates.
This talk will present a range of data supporting various aspects of this hypothesis, obtained both through online studies with literate Western participants, and ethnographic observation and studies conducted in rural northeastern Brazil. It will be shown that (a) prior knowledge interacts with information provisioning to impact individual humor preferences, (b) these preferences reflect closeness in real-world social networks, and (c) evaluations of the sense of humor of other individuals also reflect social closeness. These findings support the hypothesis that humor evolved as a subjective, interdependent signaling system for compatibility matching, and not simply as an index of objectively-evaluated traits, such as intelligence.

Erol Akcay - Evolution of motivations and behavioral responses: Integrating the proximate and ultimate causes of behavior
2010-10-11 00:00
Erol Akcay: University of Tennessee National Institute for Mathematical and Biological Synthesis (NIMBioS)There is extensive work on the evolutionary causes of social behaviors, but integration of this theory with the proximate mechanisms of behavior has lagged behind. Here, I will present a new modeling approach to achieve such integration. The model rests on goal-oriented motivations, or preferences, as the proximate determinants of behavior and describes the dynamics of a social interaction at the behavioral time scale. During these behavioral dynamics, individuals can respond to each other’s actions, and these responses ultimately drive the evolution of the proximate motivations.
We first apply this framework to the question of other-regarding motivations. We find that other-regarding motivations can evolve even when there is complete conflict of interests between the individuals, and in the absence of group- or kin-selection. We then turn our attention to the evolution of conformist motivations, and explore conditions that facilitate their evolution. Finally, we generalize our framework to include the joint effects of behavioral responses trough proximate mechanisms and selection in structured populations. The resulting model illuminates the interplay between behavioral responses and relatedness in the evolution of social behaviors. In particular, we find that behavioral responses can facilitate the evolution of group-optimal behaviors, and result in transitions between levels of selection.

Uri Gneezy - Gender differences in preferences
2010-10-04 00:00
Uri Gneezy: UCSD Rady School of Management Arthur Brody Endowed Chair in Management Leadership, Professor of Management and StrategyIn this talk I will discuss some recent findings regarding gender differences in economic experiments. The discussion will focus on gender differences in competitiveness, but will also touch on differences in risk preferences and social preferences. I will also speculate on the source of these differences, as well as on their implications.http://www.bec.ucla.edu/GneezyPaper.pdf

Aaron Blackwell - Life history, immune function, and helminths: The behavioral and immunological ecology of the Shuar of Ecuador
2010-09-27 00:00
Aaron Blackwell: UCSB Department of AnthropologyThe Shuar are a large and semi-autonomous indigenous group from the Amazonas region of Ecuador. Most Shuar subsist on a mixture of foraging and horticulture, but increasingly Shuar in many areas are becoming integrated with market economies. This talk presents fieldwork conducted amongst the Shuar between 2005 and 2009, with comparative data from the Shiwiar of Ecuador, non-indigenous Ecuadorian colono children, the Tsimane of Bolivia, and the 2005-2006 U.S. NHANES. I examine how growth and immune function are affected by market integration, household composition, and changes in pathogen exposure. Compared to the more traditionally living but closely related Shiwiar, Shuar show a higher prevalence of growth stunting. Between individuals, growth stunting is related to markers of immune activation, particularly as related to helminth infection. Biomarkers of helminth infection are associated with poorer growth in children, lower stature in adults, and decreases in inflammatory biomarkers. These results suggest that infection with parasites, such as helminths, may have hidden costs associated with changes in the allocation of resources between the competing demands of immune function and growth. In addition, higher biomarkers of helminth infection are associated with the presence of additional children in a household, suggests children in large families may face increased pathogen transmission as well as potential competition for limited parental resources.http://www.bec.ucla.edu/BlackwellPaperFinal.pdf

Quentin Atkinson - The Cultural Evolution of Human Languages
2010-06-01 00:00
Quentin Atkinson: University of Oxford Institute of Cognitive and Evolutionary AnthropologyLanguages, like species, evolve. Words and phrases compete for our favour in a struggle for existence that is analogous to natural selection. Words that survive are passed on from generation to generation in a process of descent with modification. This process has generated the thousands of languages we see in the world today. In this talk I will discuss how methods and theory from evolutionary biology can be applied to linguistic data to shed light on the ancestry of extant languages and the processes that have given rise to modern human language diversity.

Carlos Navarrete - Sexual Selection and the Psychological Architecture of Race Prejudice
2010-05-24 00:00
Carlos Navarrete: Michigan State University Department of Psychology & Evolution, Ecology, and Behavior ProgramIntergroup aggression perpetrated by men has been a persistent feature of human societies for centuries, and may have been common enough over evolutionary time to have allowed selection to shape the neural circuitry underlying the psychology of prejudice. Because intergroup aggression poses different adaptive challenges for men and women, the psychological adaptations that operate to cope with such threats may differ between the sexes as well. Because racial categories are often mentally represented as group-like entities, modern race bias should be understandable within this general framework. Results from several studies are consistent with this perspective, and show that (a) race bias is primarily directed at male exemplars of racial-outgroups, (b) men are more likely to be aggressively prejudiced than women, and (c) women are more likely to be fearfully prejudiced than men, particularly during the fertile phase of the menstrual cycle. Illustrations of how these systems may be operative in political attitudes and voting preferences for Barack Obama are presented. These results are consistent with the notion that the psychology of intergroup prejudice is generated by different psychological systems between men and women.

Elizabeth Pillsworth - Is Female Choice Overemphasized in the Evolutionary Psychology of Human Mating? Evidence from the Shuar of Ecuador
2010-05-17 00:00
Elizabeth Pillsworth: CSU Fullerton Department of AnthropologyDarwin’s theory of sexual selection emphasizes the role of female mate choice in shaping male morphology and behavior. In evolutionary psychology, the model of female choice has served as one organizing feature of research on human mating. However, in many human societies women are reported to have very little influence over their own mating decisions; rather, parents or other kin often control the marriage decisions of daughters. This has led to the claim by some that female choice has been overestimated as a selective force in human evolution, based upon the evolutionarily novel context of modern Western sexual practices. I will present data from the Shuar, a hunter-horticulturalist society in the Amazon basin of Ecuador, to highlight the ways in which women exert mate choice within a paternalistic and highly controlling environment, and demonstrate that choice need not be “free” to have an evolutionary impact.

Doug Kenrick - How the Mind Warps: Evolution and Social Cognition
2010-05-12 00:00
Doug Kenrick: Arizona State University Department of PsychologyThe human mind processes information in a famously selective and shockingly biased way. Who and what do we select for attention, encoding, and retrieval, and how, why, and when do we distort certain kinds of information in certain ways and not others? My colleagues and I have been studying how basic cognitive processes are influenced by activating fundamental human motivations such as self-protection or mating goals. We’ve found several domain-specific cognitive enhancements, decrements, and distortions: we stare at, but fail to remember, certain people in certain circumstances, we look away from, yet remember, other people in other conditions, and sometimes we differentiate members of out-groups who are normally blurred together in our memories. These motivated biases are anything but random and senseless. Instead they predispose adaptive context-sensitive decisions about whether to conform or show off, whether to fight or flirt, whether to take financial risks, and so on. At a deeper level, these biases make functional sense when considered in light of broader theoretical developments at the interface of evolutionary biology, comparative anthropology, and cognitive science. http://www.bec.ucla.edu/KenrickPaper1.pdf

Eric Alden Smith - Large-Scale Cooperation in Small-Scale Societies
2010-05-10 00:00
Eric Alden Smith: University of Washington Department of AnthropologyCollective action with low relatedness (large-n, low-r cooperation) is a common feature of human societies, in marked contrast to patterns in other species. This is particularly puzzling for small-scale societies of foragers and horticulturalists, where formal social institutions to enforce collective action are weak or absent. There is considerable disagreement regarding the evolutionary basis of such forms of collective action; some are convinced they can be explained via standard forms of mutualism, reciprocity, and coercion supplemented by reputation mechanisms, while others insist that various forms of cultural group selection are required. This debate has been protracted, and progress in our understanding of the issues appears stymied. I argue that progress can be made, but will require carefully targeted empirical evidence from naturalistic settings, particularly concerning the distribution of costs and benefits among collective action participants. I focus here on small-scale societies, and pinpoint areas in which empirical evidence could be particularly helpful. These include:
1) What are the payoff structures for empirically common forms of collective action?
2) How great is reproductive skew within groups, and what are its individual-level and institutional correlates?
3) At what frequency do groups with greater amounts of collective action prevail demographically?
I discuss ethnographic variation in Native North America to explore what patterns these phenomena might take. However, convincing answers to these questions will require carefully tailored analyses of new or existing data.http://www.bec.ucla.edu/SmithPaper1.pdf

Edward Slingerland - Why do Humanists Hate Vertical Integration?
2010-05-03 00:00
Edward Slingerland: University of British Columbia Department of Asian Studies, Canada Research Chair in Chinese Thought and Embodied CognitionCalls to “vertically integrate” (Tooby & Cosmides) or achieve “consilience” (E.O. Wilson) between the sciences and the humanities have, for the most part, been received with a great deal of hostility by humanists. This talk explores some of the reasons–good, bad, and unavoidable–for this hostility, and sketches an outline of what might profitably be called a “second wave” of consilience, one that would help to bring about a more amicable relationship between the “two cultures.”http://www.bec.ucla.edu/EdSlingerland.pdf

Dario Maestripieri - Post-Copulatory Sexual Selection and Female Mating Vocalizations in Primates
2010-04-26 00:00
Dario Maestripieri: University of Chicago Professor of Comparative Human Development, Evolutionary Biology, Neurobiology, and PsychiatryPost-copulatory sexual selection operates through two main mechanisms: sperm competition and post-copulatory female choice. Little is known about the role of female behavior in inciting sperm competition or in the expression of post-copulatory choice. Little is also known about signals that occur after, rather than before, mating. The vocalizations that primate females give shortly after mating may be sexually selected signals that play an important role in both sperm competition and post-copulatory female choice. In recent papers, we have argued that female copulation calls have two immediate functions: to encourage mating attempts by other males and to increase mate guarding by the consort male. These vocalizations may have evolved under the selective pressures of risk of infanticide and sperm competition. When male mate guarding is effective, copulation calls allow females to concentrate paternity in dominant males and benefit from their protection against the risk of infanticide. When mate guarding is ineffective, copulation calls bring genetic benefits to females through facilitation of sperm competition. In this seminar, I will present a quantitative model in which variation in female promiscuity associated with social or ecological factors affects the extent to which dominant males can monopolize females and predicts female tendency to use copulation calls in conjunction with mating. The model predicts that in species with little female promiscuity, copulation calls should be rare and occur only after mating with dominant males. In species in which females are highly promiscuous, copulation calls should be frequent and occur after mating with any males regardless of their dominance rank. Consistent with the model, I will present data showing that female copulation calls are rare or absent in primate species in which male infanticide does not occur and sperm competition is absent or weak, whereas variation in female promiscuity in species in which male infanticide or sperm competition occurs accurately predicts the extent to which mating is accompanied by copulation calls. I will also present behavioral data from captive baboons showing that female copulation calls are most likely to occur after mating with dominant males and are effective in encouraging post-copulatory mate guarding.http://www.bec.ucla.edu/DarioPaper.pdf

Justin Wood - The Evolutionary Origins of Action Comprehension
2010-04-19 00:00
Justin Wood: USC Department of PsychologyAs social creatures, we wake up every morning to a dizzying array of actions from allies and competitors, in contexts that include cooperation, resource competition and parental care. Some actions are intentional, motivated by either distal or proximal goals; some are accidental, but nonetheless result in similar consequences. How do humans comprehend such actions, and are the mechanisms that subserve this ability uniquely human or shared with other species? In this talk, I present evidence that three nonhuman primate species (cotton-top tamarins, rhesus macaques, and chimpanzees), representing the three major groups (New World monkeys, Old World monkeys, and apes) comprehend others’ actions in the same way as human infants and adults. These results illuminate the evolutionary origins of a primary socio-cognitive ability and help distinguish between competing models of action comprehension in humans.http://www.bec.ucla.edu/JustinWood.pdf

Tom Griffiths - Effects of Inductive Biases on Cultural Transmission
2010-04-12 00:00
Tom Griffiths: UC Berkeley Department of Psychology and Group Major in Cognitive ScienceLearning a language, a concept, or a social norm all require making an inductive inference, going beyond the data provided by the behavior of other people. Such inferences are underdetermined by the available data, allowing people’s biases to influence the conclusion that they reach. These inductive biases reflect the expectations that people have about which hypotheses are most likely to account for the data they observe, and the factors that make it easier to learn some languages, concepts, and norms rather than others. I will present a combination of theoretical results and laboratory experiments demonstrating that inductive biases can have a significant effect on the changes that information undergoes when it is passed from one person to another. By simplifying the process of cultural transmission down to a “diffusion chain” along which information is passed, we can examine how the inductive biases of individual agents influence the outcome of this transmission process. Assuming that the agents passing information are rational Bayesian learners, we can prove that over time the information they transmit will be transformed into a form more consistent with their inductive biases. Laboratory experiments in which diffusion chains are constructed from human participants bear out this prediction, with experiments in which a sequence of people learn from data generated by other people or reconstruct information from memory producing results that reflect their inductive biases. I will discuss the implications of these results for understanding cultural evolution more generally, as well as for identifying the circumstances under which we can expect knowledge to accumulate over time.http://cocosci.berkeley.edu/tom/papers/ilreview.pdf

Peter Gray - The Descent of Dad's Sexuality
2010-04-05 00:00
Peter Gray: University of Nevada-Las Vegas Department of AnthropologyHow does fatherhood impact men’s sexuality? In this presentation, we review some of the core facets of paternal sexuality. Cross-cultural patterns of fertility beliefs suggest that a physiological basis of paternity is usually recognized, but without a link to mid-cycle ovulation. Male anatomy and semen components are optimized for successful reproduction in the face of relatively low sperm competition. Following conception, cross-cultural variation in sexual practices during gestation exists. In some societies, men are expected to engage in frequent intercourse to help foster a fetus’ growth, whereas in others intercourse quickly plummets following recognition of a pregnancy. Possible explanations for this variation are suggested. Postpartum declines in sexuality are robust in meta-analysis of western societies and cross-culturally, but also responsive to a number of variables. The resumption of sexual activity within a couple can be best understood with reference to reductions in female libido, breastfeeding, the availability of alternative sexual partners (e.g., in polygynous marriages), marital quality and partners’ ages. The human propensity to have sex in private also poses challenges to the resumption of sexual activity, especially in light of social sleeping arrangements. Implications and directions for future research are suggested, including the call for researchers and analysts to consider reproductive state (e.g., postpartum) more formally in sexuality data, and for more inclusive samples (e.g., gay fathers and stepfathers) addressing paternal sexuality.http://www.hup.harvard.edu/catalog/ANDMAN.html

P. Jeffrey Brantingham - Burglars, Bangers and Bombers: The Behavioral Mechanisms Underlying Repeat Victimization
2010-03-29 00:00
P. Jeffrey Brantingham: UCLA Department of AnthropologyIt is well known that victims of both violent and property crime experience an increased risk of being victimized again, especially during a brief interval of time following the initial event. Ethnographic evidence suggests, in the case of property crime, that offenders seek out previous targets to replicate previous successes. In the case of violent crime, by contrast, retribution plays an important role in ramping-up and sustaining cycles of violence. Self-exciting point process models are used to study the time-course of burglary in Los Angeles, violent acts and reprisals between rival gangs in Los Angeles and insurgent attacks in Iraq. Self-excitation appears to be a generic statistical structure for crime hotspot formation across most, if not all types of crime.
This work is a collaborative effort with Andrea Bertozzi, George Mohler, Martin Short and Erik Lewis (UCLA Math), as well as George Tita (UC Irvine Criminology) and the Los Angeles Police Department. The work was supported by the US National Science Foundation.
*(Co-Sponsored by the Cotsen Institute of Archaeology at UCLA)

Peter Fashing - Behavioral ecology of East African primates: Costs and benefits of group living in colobus and gelada monkey societies
2010-03-08 00:00
Peter Fashing: CSU Fullerton Department of AnthropologyGiven that animal societies represent a collection of genetically selfish individuals that have come together to live and reproduce as part of a group, conflicts over the allocation of resources essential to survival and reproduction must routinely occur. For groups to remain stable over evolutionary time, these conflicts must be resolved to the satisfaction of all group members â€“ that is, the benefits of group life must outweigh the costs. In this talk, I will describe my past, present and future research into the costs and benefits of group living for individuals and groups of wild primates, including colobus and gelada monkeys, in East Africa, and discuss how insights gained from non-invasive, observational sampling of primate behavior and ecology can shed light on the evolution of group living in humans and other animals. http://www.bec.ucla.edu/Fashing1.pdf
