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Behavior, Evolution, and Culture Speaker Series Mondays 12:00-1:30, Haines Hall 352, UCLA Lunch will be provided on a first-come,
first-serve basis; we request a $6 donation. The UCLA Center for Behavior, Evolution, & Culture relies on support from diverse academic organizations and contributions from members of the public. If, like us, you believe that the future of behavioral science lies in a consilience of perspectives united by evolutionary theory, you can join in the pursuit of this goal by making a financial contribution to the Center via our secure web site at https://giving.ucla.edu/bec. Feel free to contact Daniel Fessler, Director of the Center, if you would like to discuss how you can support the Center's mission. Dr. Fessler can be reached by email at dfessler "at" anthro.ucla.edu (insert the @ symbol yourself), or by phone at 310 794-9252. Videos are
available for many of our talks. Links for each recorded talk can be found below
underneath the abstract of the corresponding guest speaker. These videos can
also be watched or downloaded for free on iTunes. You can find us at UCLA
iTunes U under the category “Social Sciences” or you can search for us by
typing “ucla bec” into the iTunes search engine. Our iTunes U videos may be
downloaded to both iPods and iPhones. SPRING QUARTER 2009 30 March: Roberto
Delgado
USC
Department of Anthropology Revisiting
Island Differences in Orangutan Socioecology: Behavioral Flexibility and
Geographic Variation Initial
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. 6 April: Joseph
Henrich
University
of British Columbia Departments of Psychology and Economics The Evolution of
Cultural Adaptations: Fijian Food Taboos Protect Against Dangerous Marine
Toxins This 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. WATCH THE VIDEO: Part 1 (Talk) Part
2 (Discussion) 13 April: Naomi
Eisenberger UCLA
Department of Psychology Why Rejection Hurts: Examining the Shared Mechanisms
Underlying Physical and Social Pain Numerous languages characterize ‘social
pain,’ the feelings resulting from social rejection or loss, with words
typically reserved for describing physical pain (“broken hearts,” “hurt
feelings”) 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?). WATCH THE VIDEO: Part 1 (Talk) Part
2 (Discussion) Wednesday, 15 April: Barbara
König
University
of Zurich Institute of Zoology Cooperation and
Social Selection - A Case Study of Communal Nursing in House Mice In 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. WATCH THE VIDEO: Part 1 (Talk) Part
2 (Discussion) 20 April: Edouard
Machery
University
of Pittsburgh Department of History and Philosophy of Science Did Morality Really Evolve? That
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. WATCH THE VIDEO: Part 1 (Talk) Part
2 (Discussion) Access the PowerPoint
presentation (.pdf) 27 April: Jenessa
Shapiro UCLA
Department of Psychology Perceiving White
Norms: Ironic Effects in Blacks' versus Whites' Judgments of Minority Targets Conformity 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. Wednesday, 29 April: Paul
Mellars University
of Cambridge Department of Archaeology Rethinking Modern Human
Behavioural Origins and Dispersal: Archaeological and Genetic Perspectives Research over the past ten years in
both DNA studies and archaeology has provided some remarkable new insights into
the origins of biologically and behaviourally modern human populations, and
their widespread dispersal from Africa to the rest of the world around 60,000
years ago. WATCH THE VIDEO: Part 1 (Talk) Part
2 (Discussion) Read the relevant papers: Model for H. sapiens
dispersal, H.
sapiens colonization of Eurasia 4 May: Scott
Johnson UCLA
Department of Psychology Mental Rotation in Adults and Infants: A Sex Difference Mental rotation (MR) is the process by which people imagine how an object would look when rotated into a different orientation in space; it may be related to performance on tasks like perspective-taking and navigation. Men typically perform faster and more accurately than women on MR tasks. Known influences on MR performance in adults are both biological (e.g., exposure to testosterone) and experiential (e.g., practice at spatial tasks), raising vital questions about the developmental origins of MR. Until recently, developmental studies were limited to children 4 years and older. This talk will present evidence that sex differences in MR performance are present far earlier, and can be observed in preverbal infants. I will also discuss the influence of task demands on MR in infants, and the possible biological and environmental contributions to performance that may shed light on the intersection of visual/motor skills and mental imagery of 3D objects early in life. WATCH THE VIDEO: Part 1 (Talk) Part
2 (Discussion) 11 May: Joseph
Manson UCLA
Department of Anthropology Adherence to
Conversational Norms in Interactions Among Strangers: Effects on Cooperation and
Expectations of Cooperation Several
studies have shown that, following brief interactions among strangers,
subjects perform better than chance at predicting whether their co-subjects
will defect in a one-shot Prisoner’s Dilemma Game (PDG). However, previous
work did not explore how such predictive accuracy was possible. Theoretical
work suggests that adherence to “arbitrary” norms serves a signaling function
that allows individuals to assort so as to maximize coordination and
cooperative efficiency. One set of norms, documented by Conversation
Analysis (CA), concerns the details of face-to-face interaction, such as
respecting interlocutors’ rights to complete each turn constructional unit
(TCU). We hypothesized that Defection in a PDG and predictions of
co-subjects’ Defections would be more likely vis-à-vis unfamiliar
interlocutors who violated conversational norms at higher frequencies. We
videotaped short conversations among same-sex triads of previously
unacquainted university students who were naïve to the impending PDG. We then
separated participants and directed each of them to (a) play a one-shot PDG
with each of their two co-participants and to predict one another’s play
decisions and (b) complete the Levenson Self-Report Psychopathy Scale (LSRP)
along with some demographic questions. From each videotaped
conversation, a mean of 3.93 min was transcribed using CA methods.
Subjects chose to cooperate in 67.7% of decisions, comparable to previous
studies of face-to-face interaction. However, participants performed no
better than chance at predicting one another’s game play decisions.
Nonetheless, personality and conversational behavior were related to one
another and to objective outcomes like game play and earnings, in both
expected and unexpected ways. We discuss these results with reference
to the co-evolution of human cultural variation, cultural capacities and
social judgment mechanisms. 18 May: Daniel
Geschwind UCLA
Departments of Human Genetics, Neurology, and Psychiatry Transcriptome Organization in Human and Primate Brain:
Connecting Genes to Brain to Cognition and Behavior We are interested in
understanding how genes influence human cognition and behavior, leading to
unique human cognitive specializations, such as language. Advances in
molecular and statistical genetics now allow us to identify genes that may be
responsible for the emergence of some of these human cognitive features. But
convergent approaches relying on data from several levels are necessary to
understand a particular gene’s relationship to brain structure and function.
To do this, we have undertaken a multidisciplinary approach involving the
study of human diseases affecting these features, such as autism, as well as
human brain evolution. We have begun to develop methods that try to take into
account the systems level organization of gene expression (the
transcriptome), and applied these to large scale data sets. This has revealed
a previously unrecognized organization to the transcriptional program in brain,
which provides a framework on which to understand adaptive changes in gene
expression on the human lineage. WATCH
THE VIDEO: Part 1 (Talk, FIRST HALF) Part 2 (Talk, SECOND HALF) Read the relevant papers: Discovering the genes that code for the
brain, Genes co-expressed in human and chimp
brains, Genome interactions with environment (and
behavior and culture) Wednesday, 20 May: Nina
Jablonski Penn
State Department of Anthropology The Evolution and Significance of Human Nakedness Humans are
distinguished from other primates by being functionally hairless over most of
their bodies. This condition evolved because hairlessness facilitated
cooling of the body by sweating. The evaporative cooling made possible
by sweating results in whole-body cooling of blood flowing in superficial
vessels, and the maintenance of constant brain temperature. The
combination of anatomical, physiological, and new genetic information
pertaining to the structure and function human skin have helped to “lay bare”
the evolution of human hairlessness and sweatiness. Hairlessness had
major consequences for the evolution of skin pigmentation and the
communication of visual information and signals through elaborated facial
expressions and, later, body painting and decoration. WATCH
THE VIDEO: Part 1 (Talk) Part
2 (Discussion) Access the PowerPoint presentation (.pdf) Wednesday, 27 May: Athena
Aktipis University
of Arizona Department of Ecology and Evolutionary Biology Walking Away from the Haystack: Models such
as Maynard Smith’s Haystack model have shown that high rates of movement
(i.e., migration, mixing, dispersal) undermine the evolution of
cooperation. However, these models generally assume that movement is
unconditional. The present model replaces the assumption of
unconditional movement with conditional movement; individuals stay in groups
that provide higher returns (by virtue of having more cooperators), and ‘Walk
Away’ from groups providing low returns. Implementing this conditional
movement rule generates a number of findings including: 1) when individuals
have high thresholds, corresponding to low tolerance for defectors, this lead
to selection for cooperation, 2) high thresholds lead to high rates of
movement initially and lower rates of movement after selection for
cooperators, and 3) population structure becomes more stable after selection
increases the proportion of cooperators in the population. These
findings challenge the standard view derived from Maynard Smith’s Haystack
model and others that high rates of movement undermine selection for
cooperation. In contrast, the current model demonstrates that high
rates of conditional movement can be associated with stronger selection for
cooperation. These results show that high rates of migration observed
in nature are not prohibitive for the evolution of cooperation, as standard
group selection models have assumed. WATCH THE VIDEO: Part 1 (Talk) Part
2 (Discussion) 1 June: Ruth
Mace University
College London Department of Anthropology Cultural Evolution and the Behavioural Ecology of
Fertility Decline A
behavioural ecological approach to human birth rates suggests they should
vary according to the costs of raising children to adulthood. Demographers and most other social scientists
are sceptical of this view, not least because birth rates are generally
lowest in the wealthiest countries;
most favour arguments based on cultural changes and cultural
influences. I will argue that
evolutionary arguments based on costs and benefits and on cultural influence
are not mutually exclusive and that variation in birth rates both within
populations and also across populations can be understood in terms of
different levels of parental investment and different constraints on parents. I will draw on data from Kenya, Ethiopia,
the Gambia and the UK to illustrate these points. Wednesday, 3 June: Devesh
Rustagi Swiss
Federal Institute of Technology, Zurich - Department of Environmental Policy
and Economics Conditional Cooperation Norm, Altruistic Punishment,
and Participatory Forest Management in Ethiopia Recent research suggests that the power of conditional cooperation norm and punishment of norm violators in sustaining cooperation depends on behavioral type composition of a group, which has been shown, experimentally, to have a predictive effect on cooperation outcome. However, because the existing evidence is exclusively based on experiments with a handful of students from the industrialized west, fundamental questions on the occurrence of this evidence across cultures, in a real world setting, and it’s policy relevance remain unanswered. Here, we report results from experiments and surveys with 679 members belonging to 49 forest user societies engaged in the management of common property forests in Ethiopia. We find that, first, 35 % members behave as conditional cooperators. Second, the share of conditional cooperators in a society has a significantly positive effect on the society’s forest management outcome, even when we control for structural determinants of cooperation. Third, conditional cooperators use costly monitoring as a mechanism to achieve a better forest outcome. The unique field settings allow us to generate this evidence in conditions where endogenous group formation, high migration and reverse causality have been ruled out. Our findings provide empirical support to the models of punishment and cultural group selection. WINTER QUARTER 2009 5 January: Caleb
Finch
USC
Davis School of Gerontology The
Role of Diet and Infection in Human Evolution Human 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. 12 January: Karthik
Panchanathan UCLA Department of
Anthropology Quantifying the
Bystander Effect in a Multi-Player Dictator Game Behavioral
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. Access the PowerPoint presentation (.pdf) 19 January: Martin Luther King, Jr. Holiday 26 January: James
Fowler
UCSD
Political Science Department Genes and Social
Networks Social
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. 2 February: Nathan
Bailey
UC
Riverside Department of Biology Same-sex Mating
Behavior and Evolution Same-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. 9
February:
Robert Boyd UCLA Department of Anthropology The Evolution of Social
Stratification In 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. Access the
PowerPoint presentation (.pdf) Tuesday, 17 February: David
Sloan Wilson SUNY
Binghamton Department of Biological Sciences & Department of
Anthropology Evolving the City:
Using Evolutionary Theory to Understand and Improve the Quality of Everyday
Life Evolutionary
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. 23 February: Daniel
Nettle
Newcastle
University Centre for Behaviour and Evolution Why is the Theory of Evolution So Hard to Understand? Even 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. WATCH
THE VIDEO (Part 1: Talk) (Part
2: Discussion) Access the PowerPoint presentation (.pdf) 2 March: Patricia
Gowaty
UCLA Department
of Ecology and Evolutionary Behavior It’s About Time: Reproductive Decisions Under Ecological and Fitness
Constraints Do 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. 9
March: Rebecca
Bliege Bird Stanford
University Department of Anthropology Why Women Hunt:
Risk and Contemporary Foraging in a Western Desert Aboriginal Community Anthropologists
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. FALL QUARTER 2008
29 September: Brian Skyrms UC Irvine Department of Logic & Philosophy of Science
Evolution of Signaling Systems With Multiple Senders and Receivers
Sender-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 – 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.
6
October: Russell Jackson CSU
San Marcos Department of Psychology
What You See is not What You Get: Evolved Distance
Perception Adaptations
Distance
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 Wundt’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.
13
October: Jessica Lynch Alfaro UCLA Center
for Society and Genetics
Biological And Cultural Evolution In Capuchin Monkeys: Mapping Behavioral Traditions Onto A Cebus Molecular Phylogeny
Despite 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.
20 October: Gary Charness UC Santa Barbara Department of Economics
Three Field Experiments on Procrastination and Willpower
We
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. Territoriality and Gender in the Laboratory
We
investigate the behavior or males and females in an experimental Prisoner's
Dilemma game with a partisan audience. In each session, there are two
same-gender groups, either both male, both female, or one group of males and
one group of females. Groups are separated into two rooms; each period,
the Prisoner's Dilemma is played in each room. One player from the
other room is seated across a table from a player from that room, with all
other participants from that room seated behind the home player and
observing. Each person plays twice, once at home and once on the road;
to make group identity more salient, inactive players receive a 1/3 share of
the payoffs from every game, so that most of one's payoffs are derived from
the actions of others.
We find
very different patterns of behavior across gender. While there is no
significant difference in the overall cooperation rates for males and
females, males cooperate substantially and significantly more often when on
the road, while females cooperate substantially and significantly more often
when at home. The difference in the difference between home and road
cooperation rates is quite significant. Our results are consistent with
effective hunter-gatherer patterns of behavior and are indeed predicted by
evolutionary psychology.
27
October: Brooke Scelza UCLA Department of Anthropology
Bush Forager, Shop Forager: Production and Consumption
Behavior in a Group of Western Desert Aborigines
Australian Aborigines in the Western Desert have gone
through a nutritional transition in the last 50 years; moving from a diet of
mainly indigenous “bush foods” 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.
3 November: John Alcock Arizona State University
Department of Life Sciences Why I Am Still a Single-Minded Adaptationist
I 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. 10 November: Noah Goldstein UCLA Anderson School of Management
The
Constructive, Destructive, and Reconstructive Power of Social Norms
Social 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
ineffectively—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.
17 November: John Mikhail Georgetown Law
Universal
Moral Grammar: Theory, Evidence, and Future Research
Scientists 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
Chomsky’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 study’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. 24 November: Tatsuya Kameda Hokkaido University Department of Behavioral Science
Emotional Functioning and Socio-Economic Uncertainty: Is
"Hikikomori" an Indigenous Cultural Pathology in Japan?
Feeling 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 – in which participants' reported their momentary emotional states 12 times per day for one-week during the course of their daily lives – and a laboratory experiment – which measured psycho-physiological responses to emotional stimuli – both supported this prediction. Implications of these findings for the well-being of youth in well-developed, post-industrial societies are discussed.
1 December: Peter DeScioli Chapman University, Economic
Science Institute The Alliance Hypothesis for Human Friendship Exploration 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.
LINKS TO PREVIOUS YEARS’ The Behavior, Evolution, and Culture
Speaker Series is generously supported by: Primary
Sponsors: Secondary
Sponsors: Tertiary
Sponsors:
For
related groups at UCLA, see the Center
for Culture, Brain, and Development , the Program for Psychocultural
Studies and Medical Anthropology, the UCLA Center for Society and Genetics, Social
Psychology , and Animal
Behavior.
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