Center for Behavior, Evolution, and Culture

Meg Crofoot - Collective Decision-Making in Complex Societies: Lessons From Tracking Wild Baboons
2015-04-13 00:00 (America/Los_Angeles)
Meg Crofoot: UC DavisAnimals living in stable social groups may often disagree about where to go, but must reconcile their
differences to maintain cohesion and thus the benefits of group living. Although theory predicts that
shared (democratic) decision-making should be widespread in nature, in species that form long-term
social bonds, considerable asymmetries in dominance and social power often exist, and some have
proposed that these differences give high-ranking individuals increased influence over group decisions.
Determining how consensus is achieved in stratified societies remains a core challenge for
understanding the evolution of social complexity. To investigate how differentiated social relationships
shape the collective decision-making process, we captured simultaneous high-resolution GPS tracks
from 26 members of a wild olive baboon troop (Papio anubis; ~ 80% of adult and subadult members,
sampled at 1hz). We then used these data to explore the relative importance of individual relationships
vs. majority rule in driving group movement decisions in this highly structured society.

No BEC This Week -
2015-04-06 00:00
No BEC This Week:

Robert Provine - From Laughter to Speech Evolution: A Bipedal Perspective
2015-03-30 00:00
Robert Provine: University of MarylandAfter an introduction to the nature and use of laughter in daily life, discussion turns to the
evolution of laughter and its implications for the emergence of speech.
Contrasts between human and chimpanzee laughter reveal that laughter is the ritualized
signal of labored breathing of rough-and-tumble, with the vocalization representing
the playful context of its origin. Laughter is primate onomatopoeia that signals, “this
is play, I’m not attacking you.” The ancestral primate laugh as performed by extant
chimpanzees is a noisy, unvoiced “pant-pant” in which one vocalization is uttered per
inward and outward breath. Naïve human observers do not recognize this utterance as
laughter, volunteering that it sounds like panting, perhaps of a dog, or even sawing or
sanding. In contrast, humans laugh as they speak, by modulating (parsing) an exhalation
into voiced bursts of “ha-ha.” Chimpanzee laughter suggests why they cannot speak–
they are confined to one utterance per inward and outward breath. The breakthrough in
human respiratory control necessary for speech came with evolution of bipedal running.
Chimpanzees and other quadrupeds have a 1:1 ratio between stride and respiratory cycle,
a necessary adaptation for forelimb impacts during running. (Without inflated lungs,
the thorax is a floppy, air-filled bag.) An unappreciated consequence of the evolution
of bipedal human locomotion is the freeing the thorax of its support function during
running, and the associated uncoupling of respiration and locomotion. Unlike the 1:1
strides per breath ratio of quadrupeds, humans runners have highly variable ratios of
4:1, 3:1, 5:2, 2:1, 3:2, or 1:1, with 2:1 being most common. With the uncoupling of
respiration and locomotion during bipedal running, there is more voluntary control of
breathing and greater opportunity for the natural selection for longer and more complex
vocalizations, including human laughter and speech. This is the bipedal theory of speech
evolution.

John Tooby - Political Epidemiology, History, and the Evolutionary Psychology of Outrage.
2015-03-09 00:00
John Tooby: UCSBDon’t shoot! Rodney King. Remember the Maine. The Reichstag Fire. Guernica. The War of Jenkins Ear. The murder of Emmet Till. Events in which one or more members of one group injure the welfare of one or more members of another group (“outrages”) typically provoke extraordinarily strong and frequently violent responses directed more or less indiscriminately at members of the group from which the offender or offenders came. Such events are treated entirely differently than parallel harms performed by individuals within groups. They unleash cultural processes in which accounts of harms rapidly spread through the group the victims came from. Generally, as news of the (sometimes fabricated) harm is transmitted from person to person, details are added to representations of the event so that the actions depicted seem harsher, more intentional, and more group-targeted. Many group members treat inflammatory portrayals of interactions and the rage they generate as a kind of precious group resource, becoming very resistant to contrary evidence, and passing these stylized narratives down generations. News of outrages strongly motivate the desire to join with others to act in a coordinated and aggressive fashion “against” the other group. A review of the historical and ethnographic record suggests that outrages play a central role in starting wars, provoking ethnic violence, and in mobilizing social movements and revolutions. The cross-culturally and cross-historically recurrent structure of these cultural and social phenomena can be understood by seeing how they naturally emerge from interactions between the evolved psychology of welfare tradeoffs, groups, adaptations for group coordination, and common knowledge. The key is that cross-group harms, if uncontested, are implicitly seen as proposing a common knowledge precedent for the degree of social domination or subordination. The psychology of outrages can be seen as a parallel and complementary adaptation to leadership—one way of solving the coordination problem of mobilizing group members to effectively act or bargain in conflicts with outgroups. Because it is normally difficult to get individuals to set aside competing agendas within groups, yet group power increases with coordination, outrages (real or fabricated) become a resource ingroup individuals strategically deploy to mobilize joint action they (as individuals) expect to benefit from.

Eduardo Fernandez-Duque - The Importance of Food, Jealousy, and Paternal Care in the Evolution of Owl Monkey Monogamy
2015-03-04 00:00
Eduardo Fernandez-Duque: Yale UniversityI will discuss published and new data from a population of monogamous owl monkeys in the Argentinean Chaco that we have been studying for almost 20 years to examine the hypothesis that social monogamy is a default social system imposed upon males because the spatial and/or temporal distribution of resources and females makes it difficult for a single male to defend access to more than one mate. Over the years we have tested predictions on ranging patterns, use of space, population density and the abundance and distribution of food. We have also examined the extent to which the ranging and ecological data allow us to predict demographic and life-history parameters as proxies for reproductive success.

Ben Trumble - Surviving the Flood: Risk Management, Resilience, and the Endocrine and Health Impacts of Natural Disaster in a Subsistence Population
2015-03-02 00:00
Ben Trumble: UCSBIn February 2014, catastrophic flooding impacted the Tsimane forager-horticulturalists of lowland Bolivia. Flooding decimated the subsistence lifestyle and more than two-thirds of villages were flooded (completely destroying crops and washing away most possessions); thousands fled to the nearby market town of San Borja. Widespread food insecurity and disease followed. This project examines the immediate impacts of catastrophic flooding on a subsistence population with limited support from formal institutions (e.g. government, NGO’s, insurance firms) characteristic of Industrial populations. In a sample of more than 400 families this study examines acute effects of disaster and crop/material losses on behavior, psychosocial stress, endocrine physiology, and health. We find a 2.6 fold increase in anemia and 2.4 fold increase in high white blood cell counts following the flood, as well as a nearly a one unit decrease in body mass index (BMI). Individuals with higher levels of crop loss were more present oriented in a time discounting task, and family illness predicted whether individuals moved the locations of their homes and fields homes following the flood. Natural disasters impact all populations, yet rural, indigenous populations are particularly vulnerable. Understanding factors promoting resilience in a population with limited schooling, material wealth, or access to modern healthcare is an important goal, as much of the world’s population lives in extreme poverty.

Corina Logan - How New Caledonian Crows Learn About and Solve Foraging Problems
2015-02-23 00:00
Corina Logan: UCSBNew Caledonian crows are one of the few species that make and use tools in the wild. Tool types differ across their range in an overlapping pattern, suggesting that tool designs are copied with a high fidelity and may be transmitted across generations, thus allowing for cumulative changes to occur to the lineage of each tool type over time (cumulative technological culture hypothesis). However, little is known about how these crows learn to make such tools, how this information is transmitted to others, or what they know about the problems they solve. I present results from two experiments on wild-caught New Caledonian crows examining what information observers attend to, how social information is transmitted among juveniles and adults, and whether they attend to causal information when solving foraging problems.

Federico Rossano - The Emergence of Property Concerns in Ontogeny and Phylogeny
2015-02-09 00:00
Federico Rossano: Max Plank InstituteSocial theorists as diverse as Locke, Hume, Rousseau, and Marx have suggested that without the institution of property modern civil society would not exist. All human societies care about ownership of at least some kinds of things (Brown, 1991; Hann, 1998), yet young children struggle to understand property and come only gradually to an understanding of ownership and how it may be legitimately transferred. Little is known about non-human primates understanding of property, in that they appear to have a sense of possession and will fight to protect the food that is in their physical control (Kummer & Cords, 1991; Sigg & Falett, 1985), but there is currently no evidence that they have any sense of ownership (i.e., they would respect others’ property even when they are absent) (Brosnan, 2011). In this talk I present a series of studies on preschoolers investigating their understanding of (i) under which conditions who owns what (call them ‘‘conditions of ownership’’ rules), and (ii) what implications (rights, commitments, entitlements, etc.) owning which objects carries under which conditions (call them ‘‘implications of ownership’’ rules). I will then present some additional studies investigating the role played by communication and cooperation in the sustainability of property as a social institution. I will finally compare the behavior of preschoolers and non-human primates in situations testing their tendency to respect other individuals’ properties and to protest when their property is violated.

David Funder - The World at Seven: Comparing Situations Across 19 Countries with Riverside Situational Q-sort
2015-02-02 00:00
David Funder: UC RiversideBehavior is a function of the person and the situation, and understanding the “personality triad” of persons, situations and behaviors requires assessment instruments for all three. However, until recently tools for assessing situations were not available. The Riverside Situational Q-sort (RSQ) was developed to fill this gap, and has been applied in the study of cross-situational consistency in behavior, and also used to operationalize and test implications of situational types posited by evolutionary theory. Most recently, The International Situations Project was begun as the first attempt to quantitatively compare everyday situational experience across cultures. Collaborators from 19 cultures directed college student participants (total N = 3,287) to a website (www.internationalsituationsproject.com) where, using the 89 items of the Riverside Situational Q-sort (RSQ), they described the situation they experienced the previous evening at 7 pm. The average situational Q-sort profile for each culture was compared with all others. The most similar cultures were USA/Canada, and the least similar cultures were Korea/Denmark, Korea/Estonia, and Estonia/Australia. The culture with the most similar situational experience to the others, overall, was Canada; the most distinctive was South Korea. The RSQ item that varied the most across cultures was “People are disagreeing about something” (Czech Republic highest; Japan lowest); the second least varying item was “Members of the opposite sex are present.” In general, the items that varied the most across cultures described negative aspects of situational experience; the least varying items were more positive. The RSQ is shown to be versatile tool for assessing situations in diverse research contexts.

Henrike Moll - Social Motivation and Cognition in Toddlers: Their Demands of Reciprocity and Affective Anticipations of Others’ Misguided Actions
2015-01-26 00:00
Henrike Moll: USCHumans are an extraordinarily social species. Their unique way of relating to one another becomes evident very early in ontogeny. In this talk, I will present two lines of experiments, both of which exemplify toddlers’ attunement to other persons and their awareness of others’ perceptual and epistemic states. In one line of experiments, we found that toddlers negate another person’s visibility when her eyes are occluded. Toddlers’ willingness to deny the other’s visibility was positively correlated with their knowledge of the pronoun ‘each other’—suggesting that children who reliably distinguish between reciprocal and individual acts are particularly demanding of reciprocity. In the second line of experiments, we approached the problem of false belief understanding in a novel way by assessing children’s facial expressions. We found that by the age of 2.5 years, toddlers affectively express suspense when observing how an agent acts on misguided assumptions. Both lines of experiments demonstrate impressive social motivational and social cognitive facts: Toddlers demand reciprocal perception in face-to-face encounters, and they are touched and moved when others actions are misguided. The results will be interpreted with a theoretical framework that is inspired by Vygotsky.

Gregory Clark - Nature versus Nurture in the Inheritance of Social Status
2015-01-12 00:00
Gregory Clark: UC DavisMost work studying the inheritance of aspects of social status across societies suggests two things. The first is that this inheritance is weak. Most social status for people is not determined by inheritance from parents. The second is that the strength of inheritance of status varies markedly across societies, so that status inheritance must be largely socially determined. In recent work using surnames as a means of measuring status inheritance across as many as twenty generations we show that in practice status inheritance is very strong, and that it varies surprisingly little across the societies and social systems. In this talk I propose that these surname results are compatible with genetics being the principle determinant of social status in most societies.

Thom Scott-Phillips - The Evolution of Human Communication and Language
2015-01-05 00:00
Thom Scott-Phillips: Durham UniversityLanguage is arguably humanity’s most distinctive characteristic. What, exactly, is language, and why are we the only species that has it? In this talk, based upon my recent book*, I will argue that the differences between human communication and the communication systems of all other species is probably not a difference of degree, but rather one of kind. Language is a system made possible by mechanisms of metapsychology, and expressively powerful by mechanisms of association. Non-human primate communication is most likely the opposite: made possible by mechanisms of association, and expressively powerful by mechanisms of metapsychology. This conclusion suggests that human communication, and hence language, evolved as a by-product of increased social intelligence. As such, human communication may be best seen, from an evolutionary perspective, as a particularly sophisticated form of social cognition: mutually-assisted mindreading and mental manipulation.

Simone Schnall - Social and Physiological Resources and the Perception of Space
2014-12-08 00:00
Simone Schnall: University of CambridgeTraditional theories of perception have assumed that visual processing is not influenced by top-down cognitive processes and is thus driven entirely by physical properties of the environment (Pylyshyn, 1984). For example, how a person sees stimuli such as a cup of coffee or a steep hill was thought to be only determined by factors such as the roughness of their surface and the amount of light entering the eye. However, recent research has shown that perception of space is also influenced by different bodily and experiential factors. I will review our recent work to suggest that perceptual processes take into account social and physiological resources, and that therefore perception of the world is a reflection of the extent to which one can act in it.

Larry Cahill - Title: Sex Influences on Brain and Memory: The Burden of Proof has Shifted
2014-12-01 00:00
Larry Cahill: UC IrvineAbstract: Historically, neuroscience paid little if any attention to sex
influences outside a limited area of reproductive functions. But all that
is changing, and ever rapidly, with a flurry of discoveries the past 10
years in particular about sex influences on brain function down to the
molecular level. My area of emotional memory is no exception. This talk
will examine these developments, and detail how they are apparently
irreversibly, and fundamentally, altering how the NIH funds not just
neuroscience, but all of biological science.

Nancy Dess - A Pan-Mammalian Tongue-Microbiome-Gut-Brain Axis? Implications for Health and Culture
2014-11-24 00:00
Nancy Dess: Occidental CollegeIn a 2002 BEC talk, I described the working hypothesis that bittersweet taste is a marker for sensitivity to metabolic equanimity, manifested in ways ranging from responsiveness to energy balance to emotional reactivity and stress vulnerability; data from rats selectively bred on a saccharin phenotype and, to a lesser extent, humans, were presented in support of the hypothesis. This talk provides an update on our research program, including social behavior and evidence of an association between the taste phenotype and the gut microbiome. I will draw on others’ recent research with nonhuman primates (taste polymorphisms and behavioral ecology) and humans (embodied cognition) to advocate for refinement and testing of multilevel integrative models that link individual-level taste to processes at lower (gut-brain axis) and higher (sociality, culture) levels of organization.

Hanna Kokko - Males exist. Does it matter? -- Special Time -- 9:00am
2014-11-17 00:00
Hanna Kokko: Australian National UniversityA lot of evolutionary theory involves the concept of populations climbing towards peaks of higher fitness. Such theory has been written without taking into account that in most species there are two distinct classes of individuals — males and females — that influence the evolutionary process in a distinctly different way. I will talk about this, and try to shed some light on two quite broad questions: why do males exist, and what determines how they behave?

Kiley Hamlin - Moral Babies: Preverbal Infants Know Who and What are Good and Bad
2014-11-10 00:00
Kiley Hamlin: University of British ColumbiaHow do humans come to have a “moral sense”? Are adults’ conceptions of which actions are right and which are wrong, of who is good and who is bad, who deserves praise and who deserves blame wholly the result of experiences like observing and interacting with others in one’s cultural environment and explicit teaching from parents, teachers, and religious leaders? Do all of the complexities in adult’s moral judgments reflect hard-won developmental change coupled with the emergence of advanced reasoning skills? This talk will explore evidence that, on the contrary, preverbal infants’ social preferences map surprisingly well onto adult moral intuitions. Within the first year of life, infants prefer those who help versus harm third parties, those who reward prosocial individuals and punish wrongdoers, and even privilege the intentions that drive actions over the outcomes they lead to. the second year of life, toddlers direct their own helpful actions toward helpful individuals, and harmful actions toward harmful individuals. These results suggest that our adult moral sense is supported, at least in part, by innate mechanisms for social evaluation.

Katarzyna (Kasia) Pisanski - The Sound of Size: Human Vocal Communication of Body Size
2014-11-03 00:00
Katarzyna (Kasia) Pisanski: UCLABody size can have an immense impact on the biology, ecology, and social status of an animal, but so too can ones ability to advertise or assess body size. Many species communicate their size vocally. Research investigating vocal communication of physical size in mammals, including humans, has focused on two salient and largely independent features of the voice: fundamental frequency and/or corresponding harmonics (perceived as voice pitch) and formant frequencies (resonance frequencies of the supralaryngeal vocal tract). In this talk, I will discuss the degree to which fundamental and formant frequencies reliably predict variation in body size controlling for sex and age, and their relative role in the perception or accurate estimation of body size in humans. The findings that I will present corroborate work on many other mammals whose mechanisms of vocal production, including anatomical constraints on size exaggeration, parallel those of humans. However, my findings also highlight the impact of psychoacoustic, sociocultural and perceptual biases on size communication in humans.

Leda Cosmides - Erasing Race in California and Brazil: Racial Categorization Varies Systematically with Patterns of Alliance Across Seven Brazilian States
2014-10-27 00:00
Leda Cosmides: UC Santa BarbaraAccording to the alliance detection hypothesis, racial categorization is a (reversible) byproduct of cognitive mechanisms that evolved for detecting social alliances (Kurzban, Tooby & Cosmides, 2001; Pietraszewski, Cosmides & Tooby, 2014). In southern California, showing subjects a single social interaction in which race is uncorrelated with alliance patterns produces a sharp decrease in racial categorization. But what happens in Brazil, where the social history linking race with alliance patterns is different? We conducted tests in seven Brazilian states that differ radically in their racial composition. Social class is a major dimension along which alliances are formed, and these states differ in the extent to which race predicts social class. Across states, the extent to which categorization by race decreased in response to alliance cues was highly correlated (r = .97) with the cue validity of race for predicting that targets were of the same social class as the subjects.

Scott Wiltermuth - I’d Only Let You Down: Guilt Proneness and the Avoidance of Harmful Interdependence
2014-10-20 00:00
Scott Wiltermuth: USCFive studies demonstrated that highly guilt-prone people may avoid forming interdependent partnerships with others whom they perceive to be more competent than themselves, as benefitting a partner less than the partner benefits one’s self could trigger feelings of guilt. Highly guilt-prone people who lacked expertise in a domain were less willing than were those low in guilt proneness who lacked expertise in that domain to create outcome-interdependent relationships with people who possessed domain-specific expertise. Guilt proneness therefore predicts whether, and with whom, people develop interdependent relationships. The findings also demonstrate that highly-guilt prone people sacrifice financial gain out of concern about how their actions would influence others’ welfare. As such, the findings demonstrate a novel way in which guilt proneness limits free-riding and therefore reduces the incidence of potentially unethical behavior. Lastly, the findings demonstrate that people who lack competence may not always seek out competence in others when choosing partners.

Carl T. Bergstrom - Dealing With Deception in Biology
2014-10-13 00:00
Carl T. Bergstrom: Washington UniversityOver the past 3.5 billion years, living organisms have evolved to acquire, store, analyze, and transmit information. This information processing capacity has allowed organisms to build up increasingly complex social organizations predicated on the effective coordination and cooperation. Coordination and cooperation in turn require honest communication among the participants in a social group. To function effectively, however, social systems need to overcome various strategic issues surrounding the threat of deception: Why do agents share information even when their interests conflict? Why don’t cheaters exploit and undermine communication by sending deceptive signals? How do communicating parties avoid eavesdropping and signal tampering? Such problems arise among the individuals within complex animal societies such as baboon troops, cooperatively nesting birds, and social insects, and also among the cells within any single multicellular organism. I argue that the threat of deception can be broken down into at least two categories: 1) cases in which the legitimate members of the social institution have some overlap in interests, but they also have individual incentives for deception, and 2) cases in which non-members of the social organization attempt to parasitize and exploit the system by subversion and other forms of trickery. We see the former category in the evolution of mate-choice signals; we see the latter in the evolution of immune strategies to deal with pathogens. I will discuss the problem of deception in biological systems, describe how these problems can be formalized using mathematical game theory, and outline some of the strategies that organisms use to overcome these problems.

Joshua Greene - Moral Tribes: Emotion, Reason & the Gap Between Us and Them
2014-10-08 00:00
Joshua Greene: Harvard UniversityIn this talk I’ll present some of the main themes in my book of the same title. First, there are two general kinds of moral problems: The original moral problem is the problem of cooperation, the “Tragedy of the Commons”—Me vs. Us. Distinctively modern moral problems are different. They involve what I call the “Tragedy of Commonsense Morality,” which is about conflicting values and interests across social groups—Us vs. Them. Second, there two general kinds of moral thinking: “fast” intuitive thinking that is efficient but inflexible, and “slow” moral reasoning that is flexible but inefficient. I’ll present evidence that “fast” thinking is good for solving more basic moral problems (Me vs. Us), but that we need “slow” moral thinking to handle modern moral problems (Us vs. Them).

Trent Smith - Evolution, Economic Insecurity, and the Modern Obesity Epidemic
2014-10-06 00:00
Trent Smith: University of OtagoWhy have obesity rates risen sharply around the world since 1980? In biological perspective, humans and other animals are thought to have evolved the ability—and the propensity—to store energy as body fat in order to survive periods of starvation. While food may be more abundant than ever today, it is becoming increasingly clear that neoliberal economic policies have been progressively shifting more and more risk onto households over the period in which body weights have risen most dramatically, and that obesity rates have risen most in countries that have pursued such policies most aggressively. A growing body of research now supports the “economic insecurity hypothesis,” which posits that uncertainty with respect to one’s material well-being may be an important root cause of the modern obesity epidemic. This lecture will review evidence supporting this hypothesis, from both the natural sciences and from econometric studies performed at the level of individuals, of demographic groups, and of countries. Implications for public policy will be discussed.http://www.business.otago.ac.nz/econ/Personal/ts_files/thumbprint.pdfhttp://www.business.otago.ac.nz/econ/Personal/ts_files/insecurity.pdfhttp://www.business.otago.ac.nz/econ/Personal/ts_files/stressdiet.pdfhttp://econpapers.repec.org/paper/agsaaea13/151419.htm

Greg Bryant - The structure and functions of human laughter
2014-06-02 00:00
Greg Bryant: UCLA Department of Communication Studies, Center for Behavior, Evolution and Culture Laughter is a universal vocal signal ubiquitous in human social interaction and homologous to play vocalizations across several primate species. In this talk I will describe two different lines of research on the production and perception of laughter. One series of experiments examined the perception of spontaneous versus volitional laughter. Specifically, we explored relationships between particular acoustic features of laughs and judgments of how “real” they sounded, as well as a study examining the connection between spontaneous human laughter and nonhuman animal vocalizations. In another series of studies, participants across 24 societies reliably identified affiliative partners from extremely brief, decontextualized clips of recorded conversational co-laughter. Several acoustic dimensions contributed to people’s judgments of affiliation, and these results did not vary substantially across population samples. Overall, laughter is an important social vocalization with deep evolutionary roots, unique acoustic features, and a variety of possible communicative functions, both within and between groups.

Stacy Rosenbaum - The development of male social partner preference in maturing mountain gorillas
2014-05-19 00:00
Stacy Rosenbaum: UCLA Department of Anthropology, Center for Behavior, Evolution and Culture Social relationships between adult male mountain gorillas and the infants in their groups are quite remarkable, characterized by extreme tolerance, grooming, playing, and many hours of male “babysitting.” This is true even in the 40% of groups that contain multiple adult males, where paternity certainty is low. My previous work demonstrated that 1) low-cost parenting is the most likely function of these relationships, and 2) preferences for individual male social partners persist across considerable time spans, even after social upheaval. This talk will examine the beginnings of such relationships, specifically the role maternal facilitation plays. Mothers increase their time near adult males in the first year after infants are born, and there is some evidence that they narrow their male social circle, spending more time near one preferred male than they do when infants get older. For a subsample of the population, male rank is a much better predictor of females’ choice of male social partner than either paternity or mating history. I will discuss the implications these findings have for understanding paternal kin discrimination and the evolution of intra-species variability in social structure.

Kelly Gildersleeve - Meta-analytic and Experimental Investigations of Shifts in Women's Mate Preferences and Attractiveness across the Ovulatory Cycle
2014-05-12 00:00
Kelly Gildersleeve: UCLA Department of Psychology, Center for Behavior, Evolution and Culture For nearly all mammals, the high-fertility period of the ovulatory cycle is the only time when sex can lead to conception. In nonhuman species, this period is often marked by dramatic changes in females’ social interactions. I’ll present two meta-analyses and several lab experiments examining similar effects in humans. Results revealed robust support for differences between high and low fertility in women’s sexual attraction to certain characteristics in men, in some aspects of women’s social behavior (e.g., their flirtatiousness), and in their attractiveness. These findings suggest that women’s mating motivations and the responses they elicit from others are sensitive to their current fertility within the cycle, with potentially important implications for their romantic relationships and social behavior more broadly.

Sam Diaz-Munoz - Tiny tamarins challenge traditional perspectives on sex roles, mating systems, and the evolution of cooperation
2014-05-05 00:00
Sam Diaz-Munoz: UC Berkeley Department of Plant and Microbial Biology and Integrative Biology Tamarins (Saguinus sp) are small Neotropical monkeys that, with other callitrichines, exhibit the most extensive cooperative breeding system of any non-human primate. In this presentation, I will draw on recent studies of tamarins and other callitrichines to underscore the importance of cooperative infant care to their complex social system. I review how callitrichines were originally classified as monogamous, but instead have one of the most flexible social organizations among mammals and birds. I highlight how social organization responds to different ecological conditions and how this flexibility represents a challenge to the concept of the mating system. I suggest that the cost of infant care is a main driver of atypical sexual roles, with intense female reproductive competition and extensive cooperation among males in reproductive contexts. I discuss other species that share elements of social organization with Saguinus tamarins, including humans. Given that increasing evidence points to a cooperatively breeding past for early humans, I advocate for an increasing focus on callitrichines as study systems for understanding the evolution of cooperative behavior in humans and all animal societies.

Jeffrey Schloss - Ecstatic Religious Rituals as Oxytocin-mediated, Hard-to-fake Signals of Cooperative Commitment?
2014-04-28 00:00
Jeffrey Schloss: Westmont College Department of Biology A prominent evolutionary account of “religious cognition” is that it emerged as a byproduct of agency detection mechanisms biased toward false positives, which were exapted as cultural innovations of moralizing gods helped stabilize cooperation by controlling defection in large-scale interactions. Although there is some empirical evidence for this account, along with the concomitant claim that religious rituals function as costly signals of commitment, if the cost of such rituals is less than their benefit, they need not function as honest signals of ascent. This talk will examine the proposal that some kinds of religious rituals associated with autonomically mediated behaviors such as blushing, shivering, fainting, and ecstatic speech, may function as hard-to-fake, though not costly, signals that both convey and promote cooperative intent. I will describe results from experiments in which human subjects engaged in a variety of religious and non-religious group activities – including Pentecostal worship – followed by participation in a series of decision tasks in standard economic games. Indices of trust, trustworthiness, generosity, and conditional responsiveness varied significantly between treatments. Measures of prosociality were correlated with the effect of group activity on plasma oxytocin. I will discuss the implications and limitations of these findings for evolutionary accounts of religion and for our understanding of ritualized group behaviors as facilitators of cooperation.

Josh Tasoff - A Biotic Economics Framework for Microbial Trade
2014-04-21 00:00
Josh Tasoff: Claremont Graduate University School of Politics and EconomicsA significant fraction of all life in the biosphere exists in complex communities in which crossfeeding is essential. In the same way that firms and consumers exchange a vast array of goods in modern markets, organisms exchange essential resources to promote their growth. Here, we present a framework based on general equilibrium theory from economics to predict the population dynamics of crossfeeding microbial communities. Analysis of a special case of the model involving two crossfeeding microbes yields several novel insights: (1) the economic concept of comparative advantage is a crucial condition for trade-based mutualism between species, (2) species that contribute more resources increase their growth rate but at the expense of a lower share of the total population, and (3) the inability to produce essential metabolites (i.e. auxotrophy) can be a selective advantage that explains its prevalence in microbial ecosystems. To test our model experimentally, we construct a synthetic syntrophic consortia of Escherichia coli and manipulate the cells’ ability to exchange essential amino acids. Experimental data are consistent with those generated by our model. This biotic economics framework provides a foundation to tackle key questions in microbial ecology and evolution and has useful applications to engineering synthetic ecosystems.

Christopher Schmitt - The genomics of obesogenic growth during development and adult-onset obesity in captive vervet monkeys: Preliminary results and potential for studies in the wild
2014-04-07 00:00
Christopher Schmitt: UCLA Center for Nuerobehavioral Genetics Obesity is increasingly prevalent worldwide, and has severe negative impacts on public health. Obesity arises from a complex interaction of genetic predisposition and environment that can accumulate throughout life. Although increasing evidence points to the importance of early development in the manifestations of adult disease, few studies have been undertaken of developmental measures that might be associated with adult obesity risk. The search for obesogenic markers during development in humans is complicated by the ubiquity of diets high in fat and simple carbohydrates, and the difficulty in assessing the actual diets of study subjects. This research investigates the genetic underpinnings of adult onset obesity and obesogenic growth trajectories from birth to adulthood in a genetically well-characterized model system under a controlled diet and environment: the African green monkey (Chlorocebus aethiops sabaeus) in the Vervet Research Colony at Wake Forest University.
We currently have some power to identify SNPs associated with these obesogenic traits, but the sample size must be increased. With further sampling, a more detailed examination of growth trajectories, in combination with novel biomarkers such as the SNPs discovered in this study, may be used to assess early obesity risks and promote the discovery of novel biomedical interventions. Perhaps of more interest to evolutionary anthropologists, the results of this captive study could easily be extended to wild populations. Our research group has already sequenced the genomes of hundreds of vervet monkeys from across their ancestral ranges in Africa, and in an isolated wild population on the islands of St. Kitts & Nevis in the Caribbean. This research raises the exciting possibility of assessing phenotypic plasticity and environmental impacts on trait expression in the wild associated with SNPs that are obesogenic in captivity.
