Center for Behavior, Evolution, and Culture

Heather Watts - Influences of social behavior on survival and reproduction in birds and mammals
2012-01-30 00:00 (America/Los_Angeles)
Heather Watts: LMUPatterns of survival and reproduction are known to be influenced by prevailing environmental conditions. In this talk, I will draw from my research on gregarious mammals and birds to examine how the social environment can affect these two components of fitness. First, I will discuss how social status, group size and maternal support influence survival and reproduction in the spotted hyena (Crocuta crocuta), a large carnivore that lives in complex social groups much like those of cercopithecine primates. Second, I will present my recent research investigating the effect of social cues on reproductive timing in the pine siskin (Spinus pinus), a nomadic North American finch with a flexible breeding schedule. Throughout, I discuss what these findings tell us about the evolution of behavior in these species.

Keise Izuma - Social Reward Based Decision-Making in Humans
2012-01-23 00:00
Keise Izuma: Cal TechHuman behaviors are influenced by the concern for social reputation (e.g., how other people think of us). It is well known in behavioral sciences that individuals tend to behave in a more egoistic manner under guaranteed anonymity, whereas less anonymous situations (e.g., the presence of others) increase pro-social behaviors. These observations are consistent with theoretical studies suggesting that reputation might be a key mediator of aspects of altruistic behavior that are uniquely human. Thus, reputation may be a unique and important aspect of our species that incentivizes self-interested individuals to conform to social norms. In this talk, we will present the results of three functional magnetic resonance imaging (fMRI) studies showing that the medial prefrontal cortex and striatum play key roles in representing one’s own reputation and making decisions based on social reward (positive reputation). We will also present evidence that social reward based decision-making is selectively impaired in high functioning adults with autism.

Roberto Schonmann - A new approach to evolution in group structured populations.
2012-01-09 00:00
Roberto Schonmann: UCLA Department of Mathematics, Sao Paulo University Department of Applied MathThe evolution of cooperation and altruism are fundamental scientific challenges highlighted by their role in the major transitions in
life’s history, when natural selection acted simultaneously on several competing levels. The relevance of basic concepts, including group selection and Hamilton’s rule remain nevertheless controversial.
In this talk I will address these problems by introducing a new framework for modeling evolution in group structured populations, incorporating inter- and intra-group competition and migration. Combining group-centric with gene-centric perspectives in a constructive group/kin selection approach, we build methodology that allows for the analysis of arbitrary non-linear fitness functions, resulting from complex multi-individual interactions accross life cycles. This provides extensions of Hamilton’s rule and reveals conditions under which altruism can evolve when rare, but genetic relatedness in groups is modest. Emphasis on linear public goods games has supported the belief that inter-group selection favoring altruism
could only override intra-group selection favoring selfishness under exceptional conditions. In contrast, we show that for iterated public goods games, in which altruists cooperate or not in each round based on previous outcomes altruism can spread even when groups are large,
selection is weak and migration rates are substantially larger than the
inverse of group size. To obtain this result we show that in the absence of selection, when groups are large, the fraction of group members that are close relatives of a randomly chosen individual has a non-Gaussian distribution with a fat tail. As a consequence, even when altruistic alleles are rare in the population, they have a significant probability of concentrating in some groups, accruing substantial reproductive gains through synergy. (This is joint work with Renato Vicente and Nestor Caticha, from Sao Paulo University.)

Alison Gopnik - Childhood dependence and adult intelligence: Children as the Research and Development Division
2011-11-28 00:00
Alison Gopnik: UCBOne of the most striking generalizations in evolutionary psychology is the correlation between sophisticated and flexible learning-based knowledge in adult organisms and a long protected period of immaturity in the young. In terms of the classic altricial vs. precocial, or r vs. k distinction in evolutionary biology, the altricial species are more likely to rely on learned information as adults. Human beings, of course, have a particularly extended childhood, and are particularly marked by their reliance on learning. This fact suggests that there may be a kind of cognitive division of labor between children and adults. Children are, as it were, the research and development division of the human species, while adults are production and marketing. Children are designed to be particularly good at learning and exploration and adults are designed to exploit the information they have learned as children for purposes of planning. I will review a wide range of developmental and neuroscientific evidence that supports this hypothesis, including some very recent studies in our lab that empirically show that children may be better causal learners than adults. In particular, I will discuss this idea in light of recent work on the computational bases of cognitive development using ideas about probabilistic models and Bayesian learning.

Joel Sachs - Evolutionary origins and stability of bacterial symbioses
2011-11-21 00:00
Joel Sachs: UCRBeneficial bacteria improve our health and are crucial to crops plants and fodder animals. However, symbiosis is evolutionarily unstable: harmful mutants can invade symbiont populations and cause cooperation to collapse. My research encompasses both theoretical and empirical work on the evolution and maintenance of bacterial symbioses with eukaryotes. My theoretical work seeks to understand how symbiotic cooperation is maintained and to predict the conditions in which exploitative / pathogenic mutants invade. This theory has important applications for medicine (maintenance of gut, oral flora symbioses), agriculture (optimization of nitrogen fixing symbioses) and bio-production (e.g., selection of bacteria to perform biochemical reactions). My empirical interests are broad and I use a combination of experimental, molecular and genomic approaches. Currently, there are two overlapping research programs within my lab. One approach employs wet-lab techniques to study the evolution and breakdown of nitrogen-fixing plant symbioses (rhizobia). Our second and newer research program is mainly bioinformatic and investigates the origins and stability of bacterial symbioses writ large (e.g. across whole bacterial lineages) and thus over deep evolutionary time.

James Andreoni - Accidental Altruism: Economic Research on the Social Aspects of Giving.
2011-11-14 00:00
James Andreoni: UCSDGiving to those in need is inherently a social act. First, altruistic giving requires empathy for, or perhaps simply awareness of, those who are needy. Second, giving nearly always involves a social interaction between the donor and someone seeking a donation. Third, those who are generous tend to be admired by others, and people care both about admiring and being admired. This presentation will discuss recent research in both the lab and the field on audience effects, the power of asking, the coercive nature of empathy over simple awareness, and how ethnic and religious diversity influences charitable giving.

Simone Schnall - Emotions, Intuitions, and Morality
2011-11-09 00:00
Simone Schnall: CambridgeHow do people tell right from wrong? It used to be assumed that moral decisions are based on rational thought, such that people determine on objective facts and logical analysis what is morally acceptable behaviour. More recently, however, empirical findings suggest that decisions about morality and ethical behaviour are far from rational, but are often guided by emotional and other intuitions. I will discuss my research showing that first, embodied feelings and intuitions influence moral judgments, and second, positive moral emotions can be harnessed to bring about positive behavioural change. These findings suggest that emotions and intuitions play a powerful role in moral considerations

William Harbaugh - Competitive preferences across age and gender
2011-11-07 00:00
William Harbaugh: U of OregonOne potential explanation for some of the differences in incomes between men and women is a difference in preferences for economic competition. In experiments with real effort and cash payoffs men are more likely to select into winner-take-all tournaments, while women tend to choose individual piece-rate pay or equal payments based on group performance. This talk examines how these relative gender differences vary across age and over the menstrual cycle. With an eye towards possible policy interventions we also examine differences in the demand for feedback information, and differences in how the effect of feedback on past performance affects choices about competition.

Robin Nelson - Contextualizing Kinship: A Bio-cultural Study of Families and Health in Jamaica
2011-10-31 00:00
Robin Nelson: UCRIn this talk, I will explore the extent to which variability in the quality of familial and social relationships is correlated to the phenotypic expression of biological indicators of health status for adults and children. This research applies theories popularized in evolutionary ecology to a study of sociality and health in Manchester Parish, Jamaica. Using ethnographic methods, I identified culturally salient aspects of investment relationships amongst a lower class study population. Jamaica’s unstable economic climate necessitates increased investment from social and familial contacts and thus, provides the framework for studies of this received investment. Health outcomes were measured using anthropometric and immunological analyses. In this presentation, I will discuss my findings regarding the impact of a variety of investment relationships on health outcomes for (1) adults who are involved in romantic relationships and (2) adults who were children during the post-colonial era in Jamaica and (3) a recent study of children living in state-sponsored orphanages. These findings suggest that investment relationships in Jamaica, specifically with relatives, serve as one important factor in the maintenance of good individual health. These relationships are particularly important in the context of Jamaica’s risky and unstable economic environment.

Derek Penn - Why Are We So Odd? Explaining the Discontinuity Between Human and Nonhuman Minds
2011-10-24 00:00
Derek Penn: UCLAHuman animals– and no other– build fires and wheels, diagnose each other’s illnesses, communicate using symbols, risk their lives for ideals, collaborate with others, explain the world in terms of unobservable causes, punish strangers for breaking the rules, worship ghosts and teach each other how to do all of the above.
Why are we so odd?
In this talk, I will explore what we now know (and don’t know) about the discontinuity between extant human and nonhuman minds. I will argue that this cognitive discontinuity runs much deeper than language, culture, a prosocial disposition or a “Theory of Mind” alone can explain. And I will sketch out a functional specification of where the root of the discontinuity might lie.
http://www.bec.ucla.edu/papers/penn-2011.pdf

Andrew Shtulman - Cognitive constraints on the understanding and acceptance of evolution
2011-10-17 00:00
Andrew Shtulman: OccidentalEvolution by natural selection is a theory that has unified the biological sciences but divided the general public. In this talk, I shall discuss how early-emerging, essentialist constraints on the conceptualization of biological kinds impedes learning about population-level phenomena like evolution and natural selection. Data from cognitive studies (Shtulman, 2006), developmental studies (Shtulman & Schulz, 2008) and teaching-intervention studies (Shtulman & Calabi, 2011) all suggest that students initially construe evolution as the uniform transformation of all species members – a view consistent with early views of evolution in the history of science (Mayr, 1982). Only through specialized instruction are students able to replace their “transformational” misconceptions with a correct, “variational” view of evolution, in which evolution is construed as the selective propagation of within-species variation. This transition is marked not only by an increased understanding of what evolution is but also by an increased willingness to accept evolution as true.

Alyssa Crittenden - The ontogeny of prosocial behavior: foraging and food sharing among Hadza hunter-gatherer children
2011-10-10 00:00
Alyssa Crittenden: UNLVHuman prosociality is one of the defining characteristics of our species, yet the developmental origins of altruistic behavior remain little understood. The evolution of widespread food sharing in humans helped shape cooperation, family formation, life history, language, and the development of economies of scale. While the behavioral and ecological correlates of food sharing among adults are widely studied, very little is known about what motivates children to share food. Here, in the first study to analyze food collection and distribution of hunter-gatherer children, a higher degree of genetic relatedness between sharing partners correlates with both a higher frequency of sharing and a greater amount of food shared. Among genetically unrelated sharing partners, reciprocity appears to motivate food sharing. These results support recent suggestions that prosocial behaviors and egalitarianism develop strongly in middle childhood when children acquire the normative rules of their society. http://www.bec.ucla.edu/crittenden_ucla_oct_2011.pdf

Dora Costa, Matthew Kahn - Heroes, Cowards, and Beyond
2011-10-03 00:00
Dora Costa, Matthew Kahn: UCLAIn Heroes and Cowards: The Social Face of War we used the life histories of more than forty thousand Civil War soldiers to discover when people are willing to sacrifice for the common good, what are the benefits of friendship, and what are the costs and benefits of being in a diverse community. We discuss these themes as well as the role of leadership in eliciting sacrifice, the role of social networks in mediating wartime stress, and the scarring effects of wartime experiences.

Ralph Adolphs - When the stimulus is a real person: social neuroscience studies of face-to-face interactions.
2011-09-26 00:00
Ralph Adolphs: Cal TechLike most other social neuroscience groups, my lab has been using pictures of faces as stimuli for a long time– we investigate how people look at them, what social judgments they make about them, and how their brains respond to them. But how ecologically valid is this? Recently, we have begun exploring how we respond to the presence of a real person. These studies reveal profound effects on judgment, behavior and brain activation by a real person, compared to a mere picture (or video) of them. They also point to specific brain structures that mediate these effects (notably the amygdala) and begin to shed further light on disorders of social behavior such as autism.

Charles Perreault - The pace of cultural evolution
2011-05-23 00:00
Charles Perreault: UCLA Department of AnthropologyHumans adaptive radiation has been explained by our capacity to socially learn information (culture). Culture is an inheritance system that parallels and interacts with the genetic one. Cultural variation and innovations accumulate in a population throughout time, allowing for complex cultural adaptations to evolve. Since, it is assumed, cultural evolution occurs faster on average than biological evolution, humans can adapt to new ecosystems more rapidly than other animals. The assumption that cultural evolution is faster than biological evolution, however, has never been empirically tested. In this talk I will suggest that human technologies typically change more rapidly than animal morphologies. Like biological evolution, rates of cultural evolution are inversely correlated with the time interval over which they are measured. This correlation explains in part why the pace of change in technologies appears faster when measured over recent time intervals, where taphonomic intervals are often shorter.

Federico Rossano - Structure and Development of Gestural Communication in Great Apes
2011-05-18 00:00
Federico Rossano: Max Planck Institute for Evolutionary AnthropologyIn this talk I address two crucial aspects of gestural communication in non-human primates: how gestures are acquired/developed and how similar is their use when compared to human behavior (in particular with respect to issues such as communicative intentions and recipient design).
There is general agreement among researchers that nonhuman primates gesture in sophisticated ways (Tomasello & Call, 2007; Pollick & de Waal, 2007). However, the process by which apes acquire gestures is an issue of debate. One of the central questions in this debate is whether apes acquire species-typical gestural repertoires, with little individual innovation (the “biological inheritance” hypothesis) (e.g., Genty et al., 2009), or whether they develop gestures individually through the ritualization of particular social acts (the “ontogenetic ritualization” hypothesis) (e.g., Tomasello, 1996). In the first part of the talk, I address this question by examining the relationship between the structure of a particular social interaction and the form of the gestures used to elicit that interaction. I present data on nine mother-infant Bonobo pairs as they engage in a particular social interaction: co-locomotion via a ventral or dorsal carry and I show how ontogenetic ritualization is the best account for the development of their gestural repertoire.
In the second part of the talk I present an ongoing study on food sharing in great apes, with particular focus on how they perform offers and requests and how other group members recognize and respond to these intentional actions. The main focus will be on Orang-Utangs and Chimpanzees.
In this work I start from actions (functions) and their sequential unfolding, rather than on specific gestural forms investigated out of context.
Genty, E., Breuer, T., Hobaiter, C. & Byrne, R. W. (2009). Gestural communication of
the gorilla (Gorilla gorilla): repertoire, intentionality and possible origins. Animal Cognition, 12, 527-546.
Pollick, A. S. & de Waal, F. B. M. (2007). Ape gestures and language evolution.
Proceedings of the National Academy of Sciences, 104(19), 8184-8189.
Tomasello, M. (1996). Do apes ape? In B. G. Galef & C. M. Heyes (Eds.), Social
Learning in Animals: The Roots of Culture (pp. 319-346). San Diego: Academic
Press.
Tomasello, M. & Call. J. (2007). Comparing the gestures of apes and monkeys. In J. Call
& M. Tomasello (Eds.), The gestural communication of apes and monkeys (pp. 197-220). London: Lawrence Erlbaum Publishers.

Mary K. Shenk - Why Does Fertility Decline? Comparing Evolutionary Models of the Demographic Transition
2011-05-16 00:00
Mary K. Shenk: University of Missouri Department of AnthropologyEvolutionary anthropologists have given significant attention to the global phenomenon of the demographic transition, especially the remarkable decreases in fertility that characterize it. The literature is crowded with competing theories and sub-theories, and scholars often call for more comprehensive, better-controlled studies that would allow us to distinguish between competing causal models—yet only limited comparative work has previously been done. This paper compares evolutionary models emphasizing decreasing risk, changing motivations for parental investment, and changing forms of cultural transmission as motivations for fertility decline. The goal is to determine which model, or combination of models, produces the most robust explanation of a rapid, recent demographic transition in rural Bangladesh.
Models are compared using an evidence-based statistical approach employing model selection techniques derived from likelihood theory. This approach allows quantification of the relative degree of support the data give to alternative models, even when model predictions are not mutually exclusive. Data come from a new survey conducted in rural Bangladesh in 2010 designed specifically for comparative testing. Results suggest that models emphasizing changing motivations for parental investment, including increasing payoffs to investment as well as increasing costs of and competition between children, are the best predictors of fertility decline. Yet findings also indicate that a full explanation involves variables from multiple models, and that important causal synergies underlie key predictors such as education, suggesting that multiple causal pathways are likely to be implicated in the rapidity and degree of recent demographic transitions.

Peter Nonacs - Is Kin Selection Dead and Is It Time to Move On in Understanding the Evolution of Cooperation?
2011-05-09 00:00
Peter Nonacs: UCLA Department of Ecology and Evolutionary BiologyHamilton’s theory of inclusive fitness broadly states that whether or not a trait increases in frequency is dependent on both the direct reproductive success of individuals having that trait and the help that such individuals can provide to other trait bearers for their reproduction. The latter portion of inclusive fitness is commonly known as kin selection and has become the dominant paradigm for the evolution of cooperation: I.e., helping genetic relatives reproduce can create a net increase in inclusive fitness even with a substantial loss in direct reproduction. Recently, however, Martin Nowak has argued that the mathematical foundations of inclusive fitness theory are inappropriate for predicting the evolution of cooperation (1). Edward O. Wilson has gone even further and claimed that, “Kin selection is wrong” and a “gimmick” (2). Instead, Wilson proposes cooperation evolves through group selection. Not surprisingly, their claims have drawn considerable criticism (3), with Richard Dawkins going so far as to pronounce that he has “never met anybody apart from Wilson and Nowak who takes it seriously (2).” I will look at both sides of this issue and attempt to separate the scientific concerns from the heated clashes of personalities. At issue appears to be the question of the evolutionary advantages of genetic diversity versus kinship. Both can be advantageous, but they are simultaneously incompatible. Their resolution requires a multi-level approach as nepotism favoring kin can be selected for within groups, but genetic diversity is selected for only across groups.
(1) Nowak et al. 2010. Nature 466: 1057-1062.
(2) http://www.boston.com/bostonglobe/ideas/articles/2011/04/17/where_does_good_come_from/?page=full
(3) Abbot et al. 2011. Nature 471: E1-E4.

Siobhán M. Mattison - Kinship and market integration among the ethnic Mosuo of Southwest China
2011-05-02 00:00
Siobhán M. Mattison: Stanford University Department of Anthropology and Morrison Institute for Population and Resource StudiesThe study of kinship is foundational to anthropology. Though interest in kinship waned briefly, it has recently been rekindled, particularly in the area of evolutionary ecology. In this talk, I review briefly the major trends in anthropological thought on kinship and, by way of example, explore the contributions that evolutionary and quantitative studies have made to its study. In doing so, I consider the ethnic Mosuo of Southwest China, a population that traditionally was matrilineal and engaged in subsistence agro-pastoralism, but that recently has become integrated into the wider market economy. I discuss evidence for associated change in kinship practices, arguing that such change is at least partially consistent with hypotheses from evolutionary ecology. I consider several topics of traditional interest to kinship theorists, including marriage, residence and inheritance and conclude by emphasizing the need to synthesize often disparate findings and by suggesting several avenues of future research.http://bec.ucla.edu/papers/Mattison.pdfhttp://bec.ucla.edu/papers/Mattison1.pdfhttp://bec.ucla.edu/papers/Mattison2.pdf

Daniel M.T. Fessler - The Importance of Attending to Phylogenetic Derivation in the Study of the Mind Or Why Emotions are Kludgy Or Some Gross Conclusions from the Study of Grossness
2011-04-25 00:00
Daniel M.T. Fessler: UCLA Department of AnthropologyThe evolutionary study of mind and behavior has benefited enormously from the functionality heuristic, i.e., the assumption that mental mechanisms can usefully be understood as well-designed solutions to recurrent adaptive problems. While virtually every investigator in this area acknowledges the importance of Tinbergen’s (1963) Four Levels of Explanation, in practice, emphasis in evolutionary psychology is invariably placed primarily on ultimate explanations. Although this is a productive starting point, because evolution involves the gradual modification of existing designs, the functionality heuristic will frequently lead investigators to under-emphasize, or even overlook entirely, constraints on optimality entailed by phylogeny. Likewise, even when high levels of functionality are, in fact, observed, the functionality heuristic will often fail to explain many features of the adaptation at issue, features that diminish efficiency even if they do not influence effectiveness. The study of emotions provides an opportunity to illustrate the utility of combining ultimate and phylogenetic perspectives in investigating the mind. A hybrid approach to emotions can illuminate otherwise puzzling combinations of qualia, display, cognition, and behavior, and suggests areas where we might expect constraints on optimality. Additionally, such an approach can productively generate predictions concerning the nature of emotions across species and across taxa, holding the promise of a broadly comparative evolutionary affective science that pinpoints both the commonalities and the divergences between our emotions and those of other organisms. These possibilities will be illustrated through a discussion of research on the evolutionary psychology of disgust.

Polly Wiessner - Cycles of War among the Enga of Papua New Guinea: Youths, Elders and Indoctrinability.
2011-04-18 00:00
Polly Wiessner: University of Utah Department of AnthropologyIndoctrinability, the capacity to be inculcated with values or doctrines and to accept them uncritically, poses an evolutionary puzzle because it can lead individuals to voluntarily sacrificing immediate individual interest for a belief, cause, or group. I will briefly explore the cognitive capacities underlying indoctrinability. Then I will propose that strong social selection for indoctrinability was an outcome of parent-offspring conflict in arranging marriage and in building cooperative cohorts. That is, elders used their control over the marriage market, as well as their network and information advantages, to persuade youths to uncritically accept cultural beliefs that would to align the goals of youth with their own. I will illustrate these ideas in a case study among the Enga of PNG by: (1) outlining the different agendas of elders and youth in different periods over 250 years of Enga history and (2) showing how elders manipulated indoctrination through ritual and other means to instill norms, values and beliefs that guided peace and war in pre-contact generations and even today when youths have the advantage of wielding high-powered weapons.

Andrew Delton - Welfare Tradeoffs: Computation, Reciprocity, and Social Emotions
2011-04-11 00:00
Andrew Delton: UCSB Department of Psychology and Center for Evolutionary PsychologyMembers of social species routinely make decisions that involve welfare allocations—decisions that impact the welfare of two or more parties. These decisions often involve welfare tradeoffs such that increasing one organism’s welfare comes at the expense of another organism’s welfare. In this talk, I present preliminary evidence that the mind computes a variable—a welfare tradeoff ratio—that is used to regulate this kind of social decision-making. By consulting this variable, an organism can determine when it is and is not appropriate to cede personal welfare on behalf of another. I also summarize an initial empirical test of the role of welfare tradeoff ratios in reciprocity and how the emotions of anger and gratitude might function to recalibrate welfare tradeoff ratios within reciprocal relationships. The larger theme of this talk is that thinking in terms of neurocomputational variables such as welfare tradeoff ratios helps to explain how complex behaviors—such as cooperation, generosity, and aggression—can arise from a physical device such as the human brain.

Christopher von Rueden - Why do men seek positions of status or leadership?
2011-04-04 00:00
Christopher von Rueden: UCSB Department of AnthropologyThe relationship between social status and reproductive success in small-scale societies can provide insight into how natural selection may have acted on status-seeking behavior in ancestral human environments. With data from the Tsimane horticulturalists of Bolivia and other small-scale societies, I show that high male status increases lifetime fitness, and I analyze the factors responsible for increases in surviving offspring among high status men. Interview data from the Tsimane suggest that mate acquisition and social support mediate the status-fitness relationship. Some of the fitness benefits of high status may accrue in the context of leadership within collective actions. However, observation and experimental induction of collective action suggest that Tsimane leaders do not differentially benefit from the division of spoils (although leadership may improve team efficiency). Identifying the proximate pathways by which status and leadership generate current fitness sheds light on the kinds of social relationships evolution has motivated men to maintain.http://bec.ucla.edu/papers/VonRueden1.pdf

Edward H. Hagen - Drugs are bad...for pathogens. Testing an alternative to the
2011-03-28 00:00
Edward H. Hagen: Washington State University Vancouver Department of AnthropologyCurrent neurobiological theory of recreational drug use is based on the observation that all addictive drugs induce changes in activity of dopaminergic circuitry, interfering with reward processing, thus enhancing drug seeking and consumption. On this view, recreational drugs “hijack” evolved reward circuitry.
Current theory of drug origins, in contrast, views almost all major drugs of abuse, including nicotine, cocaine and opiates, as plant neurotoxins that evolved to punish and deter herbivores. According to this latter view, plants should not have evolved compounds that reward or reinforce plant consumption. Mammals, in turn, should not have evolved reinforcement mechanisms easily triggered by toxic substances. Situated in an ecological context, drug reward is a paradox.
One potential resolution of the paradox is that humans, like other animals, might have evolved to exploit plant neurotoxins to defend against pathogens. Psychoactive substances, by definition, interfere with neural function. Psychoactivity is thus a potential cue of efficacy against pathogens with nervous systems. Specifically, recreational drug use could be a form of chemoprophylaxis (preventative medicine) or chemotherapy (palliative medicine) against pathogens such as fleas, ticks, and helminths.
The chemoprophylaxis and chemotherapy hypotheses were examined in a population of Aka foragers in the Central African Republic. The Aka have high levels of helminth infection yet little access to Western anti-worm medicines, and so might be motivated (consciously or unconsciously) to consume readily available substances that are effective against worms. The plant defensive chemical nicotine, in particular, is an effective anthelmintic. Hence, “recreational” tobacco use, which is widespread at the study site, might be a form of self-medication against helminths or other pathogens.
The chemoprophylaxis hypothesis predicts that smoking should protect against helminth infection, an hypothesis tested in a cross sectional study of nicotine exposure vs. worm burden. The chemotherapy hypothesis predicts that smoking should increase upon helminth infection, and decrease when the infection abates. The latter prediction was tested in a randomized, double-blind, placebo-controlled trial involving treatment with albendazole, a commercial anthelmintic.

Michael McCullough - Cognitive Systems for Revenge and Reconciliation
2011-03-09 00:00
Michael McCullough: University of Miami Department of PsychologyExploitation—the targeted infliction of fitness costs on another organism for the purpose of capturing benefits for the self—is a fact of life for social organisms. Because of its pervasiveness in social life, natural selection gives rise to deterrence mechanisms (e.g., thorns, toxins, defensive weaponry) designed to alter potential exploiters’ estimates of the net benefits to come from exploitation. In this talk, I situate humans’ (and other social animals’) propensities to seek revenge among other naturally selected deterrence mechanisms. Revenge-based deterrence, however, can create additional costs, including those associated with lost access to valuable relationship partners. Consequently, natural selection gives rise to subsidiary mechanisms designed to (under a fairly restricted set of circumstances) inhibit revenge-based deterrence and signal a willingness to re-establish positive relations. I conceptualize these subsidiary systems as reconciliation (or forgiveness) systems. In this talk, I introduce several lines of research in which we have: (a) searched for the social conditions that revenge and forgiveness/conciliatory behavior evolved to address, (b) searched for the computations that underlie these systems, and (c) sketched out their endocrinological substrates.

Ivy Pike - Embodying Violence and the Biocultural Approach: What can nomadic herders from Northern Kenya teach us about linking context to global health disparities?
2011-03-07 00:00
Ivy Pike: University of Arizona Department of AnthropologyGrowing efforts to carefully link social environments to biological experiences have emerged in many disciplines; Anthropology is no exception. This integrative perspective aims to place bodies in context with a strong awareness of the role gradients of inequality play in shaping population variation in health. While much anthropological research contributes to our understanding of extreme inequality on health (e.g. Farmer 1999, 2003) less attention has been paid to the precise mechanisms that allow context to be embodied. The most precise mechanisms derive from evolutionary biology with an emphasis on environment / biology interactions, especially as they unfold across growth and development. In this paper, I draw on a case study of nomadic herders from Northern Kenya to examine the benefits of an evolutionary informed approach to studying global health disparities. The herding communities experience geopolitical marginalization with endemic violence in the form of AK-47 raids. Such a backdrop comes with a suite of predictable health indicators but with some noteworthy differences. These differences are linked to the sociocultural environment and to the community responses to violence. As such, they create an opportunity to link context to the biology of inequality in more nuanced ways as an integrative model for global health policy.

Sarah Mesnick - Sperm whale social structure: kith and kin. Implications for behavior, culture and conservation
2011-02-28 00:00
Sarah Mesnick: Southwest Fisheries Science Center, NOAA Fisheries ServiceKnowledge of the genetic structure of social groupings provides the basis for understanding the relative influences of kin selection and reciprocity in the evolution of individual behavior and for understanding the basis of population structure, which is important for conservation. Sperm whale, Physeter macrocephalus, groups comprised of females and dependent young were once thought to be strictly matrilineal, with a social structure similar to that of African elephants. We investigated this hypothesis using samples from 3 completely sampled mass strandings in Tasmania (n = 11, 37, 64 individuals respectively) and 55 partially sampled groups from the eastern North Pacific. We used mitochondrial (400 bp of the hypervariable control region) and nuclear (six microsatellites and 36 single nucleotide polymorphisms) markers and the sex of individual sperm whales to estimate genetic relatedness within and among groups. The preliminary results indicate that sperm whale groups were not purely matrilineal in structure. Rather, groups were comprised both of individuals that had no close relations and of individuals accompanied by potential first and second order relations, some potentially related through their fathers and others through their mothers. Groups were composed of mixed matrilines, as evidenced by the presence of 1 – 5 mtDNA haplotypes (maternally inherited) per group. The mean coefficient of relatedness for the completely sampled groups ranged from 0.15-0.27. The groups were comprised of small clusters of related individuals although in all groups there were several individuals with no relations closer than those expected by chance. Pairs of individuals with high coefficients of relatedness, but different mtDNA haplotypes, were consistent with patterns of paternal half sibs. Three subadult males with unique mtDNA haplotypes were found among a group of adult females indicating that their mothers were not present, an unexpected finding. Some old (and very old) females, some of whom were accompanied by close relatives and others not, were lactating. These results cause us to rethink the relative influences of kin selection and reciprocity in the evolution of individual behavior (e.g., babysitting, communal defense). We suggest that for the sperm whale, and other cetacean species that live, raise young and contend with predators in the open ocean, the integrity of the bonds developed through association, cooperation and lactation, are as strong as blood relations.
For this presentation, I will summarize what is known about sperm whale social and population structure from recent genetic work in our laboratory and observations of social interactions at sea. Additional insights from the acoustic research of colleagues provide the background for cross disciplinary, cross- taxa discussion on three topics: (a) social structure within females groups and observations during an attack by killer whales; (b) social transmission of a novel foraging behavior (depredation on demersal long lines) among adult males in Alaska; and (c) population structure – geographically defined stocks and culturally defined clans – for conservation and management.
http://bec.ucla.edu/papers/MesnickPaper1.pdfhttp://bec.ucla.edu/papers/MesnickPaper2.pdfhttp://bec.ucla.edu/papers/MesnickPaper3.pdf

Ádám Miklósi - Dog-human social interaction: Old wine in new bottles?
2011-02-25 00:00
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.
