Joseph Manson - Father-Daughter Inbreeding Avoidance Reduces Male Reproductive Skew in a Wild Primate Population
2005-10-03 00:00 (America/Los_Angeles)
Joseph Manson: UCLA Department of AnthropologyInbreeding reduces fitness in various taxa, and several behavioral and physiological mechanisms have evolved that inhibit fertile matings between close kin. Most commonly, members of one or both sexes disperse before breeding. In primates, males usually disperse and females often benefit from lifelong relationships with maternal kin within the group. Females thus risk breeding with their father if the tenure length of the dominant male, who usually sires most group offspring, exceeds the time it takes daughters to mature. Attempts to determine whether such co-resident father-daughter pairs systematically avoid inbreeding have produced equivocal results, and no published studies have addressed this question by genetically ascertaining paternity in a wild population. We determined paternity for 117 wild white-faced capuchins (Cebus capucinus) born into our study population. As expected, alpha males dominated reproduction. However, while siring the great majority (79%) of the offspring born to unrelated females, alphas sired only 6% (1 of 17) of the offspring conceived by their daughters during their tenures, providing evidence for effective inbreeding avoidance without female dispersal.

Antoine Bechara - Decision-Making and Impulse Control After Frontal Lobe Injuries
2005-10-10 00:00
Antoine Bechara: USC Department of PsychologyFor a long time, the prefrontal cortex has been considered a â€œnon-functionalâ€ brain area, and understanding its function has lagged behind nearly all other areas. This is no longer true since appreciation of the vital role that this brain region plays in adaptive behaviors, and especially decision-making, is now evident more than ever. I will highlight the recent progress that has been made in this area of research. Decision-making is a term often referred to in the psychological literature as one of the â€œexecutive functionsâ€, which play a role in managing (like an executive) other cognitive functions, such as memory, attention, and language. Considerable research efforts have been directed towards differentiating various processes of executive functions, but much of this effort in the past has focused on the dorsolateral prefrontal cortex (DLPC) sector. I will focus on decision-making and its link to the ventromedial prefrontal cortex (VMPC), and highlights the role of evolution in shaping the function of this area of the brain.

Susan Perry - Social learning in wild capuchin monkeys
2005-10-17 00:00
Susan Perry: UCLA Department of AnthropologyRecently, discoveries of site-specific behavioral patterns such as the use of hammers and anvils or stick tools in extractive foraging have been documented in wild ape populations. Such discoveries have given rise to much speculation regarding the evolution of cultural capacities in humans, and claims have been made that chimpanzees have a greater capacity for â€œcultureâ€ than any other nonhuman animal. However, theoretical models used to predict the circumstances under which social learning is expected to become important would not predict unusually high reliance on social learning to be unique to apes. Capuchin monkeys, for example, by virtue of their gregarious, tolerant nature, omnivory, extreme dependence on alliance partners, and extractive foraging niche, would be predicted to be highly reliant on social learning.
In this talk, I present the findings of a cross-site investigation (4 study sites, 13 social groups, 10 researchers, 19,000 hrs of data) documenting behavioral variation in social conventions and foraging techniques in white-faced capuchin monkeys. Whereas the ape â€œcultureâ€ researchers stopped at cross-site comparisons and declared the observed variation to be cultural by process of elimination, I continued to investigate the source of the variation by conducting cross-sectional and developmental studies in my data base from Lomas Barbudal (5 social groups, roughly 30,000 hrs of data dating from 1990). In this talk I present data on social conventions and also data on the acquisition of foraging techniques in young capuchins. Social influence is most important between the ages of 2-4 years, and by age 5, capuchins have conformed to the technique they observed most. This conformity takes place over a very slow time scale, contrary to theoretical expectations about the speed of social learning.

Francisco J. Ayala - Darwin's Greatest Discovery: Natural Selection versus Intelligent Design
2005-10-24 00:00
Francisco J. Ayala: UCI Departments of Ecology & Evolutionary Biology and PhilosophyDarwin is deservedly given credit for the theory of biological evolution. He accumulated evidence demonstrating that organisms evolve and diversify through time. Most important, however, is that he discovered natural selection, the process that accounts for the adaptive organization of organisms and their features; that is, their “design.” But the design of organisms is not intelligent, as it would be expected from an engineer, but imperfect and worse: the defects, dysfunctions, oddities, waste-and even cruelty and sadism if judged by human values-that pervade the living world are incompatible with their being the outcome of an intelligent designer, unless this designer would also be intentionally deceitful and malevolent.

Paul Zak - Oxytocin Increases Trust in Humans
2005-10-31 00:00
Paul Zak: Claremont Graduate University Neuroendocrine Foundations of Trust Department of EconomicsThe traditional view in economics is that individuals respond to incentives, but absent strong incentives to the contrary selfishness prevails. Moreover, this â€œgreed is goodâ€ approach is deemed â€œrationalâ€ behavior. Nevertheless, in daily interactions and in numerous laboratory studies, a high degree of cooperative behavior prevailsâ€”even among strangers. A possible explanation for the substantial amount of â€œirrationalâ€ behavior observed in markets (and elsewhere) is that humans are a highly social species and to an extent value what other humans think of them. This behavior can be termed trustworthinessâ€”cooperating when someone places trust in us. A number of recent experiments from my lab have demonstrated that the neuroactive hormone oxytocin facilitates trust between strangers, and appears to induce trustworthiness. In rodents, oxytocin has been associated with maternal bonding, pro-social behaviors, and in some species long-term pair bonds, but prior to the work reviewed here, the behavioral effects of oxytocin in humans had not been studied. This presentation discusses the neurobiology of positive social behaviors and how these are facilitated by oxytocin. My experiments show that positive social signals cause oxytocin to be released by the brain, producing an unconscious attachment to a stranger.
