Origins of Prosocial Preferences

We vote, recycle, give blood, and volunteer for committee assignments. This kind of behavior is motivated by empathy and concern for the welfare of others. What are the phylogenetic roots of prosocial preferences? To answer this question, my colleagues and I have begun a series of experiments with chimpanzees to evaluate their responses when given the opportunity to provide benefits to others. For the first results from this project see Silk et al. 2005. Results of additional experiments are forthcoming soon (hopefully).

Adaptive variation in primate sex ratios

Do female primates adjust the sex ratio of their offspring in relation to their own rank or ecological conditions? To anwer this question, Gillian Brown and I have conducted a series of meta-analyses of sex ratio biases in primate groups. Our results suggest that observed biases are the product of stochastic variation in small samples. For more details see Brown & Silk 2004, Silk et al. 2005. We are now working on species-level sex ratio biases in the primate order, focusing on adaptations to Local Resource Competition and Local Resource Enhancement. Stay tuned.

What are friends for?

For humans, and perhaps for other primates, the capacity to form and maintain close social bonds has an important impact on health and happiness. In humans, friendship seems to transcend the calculus of kin selection or reciprocity. People don't keep careful track of help given and received from friends, and make some effort to obscure the magnitude of their contributions. This kind of relationship defies the logic of evolutionary theory, but seems to play an important role in our lives.I am interested in the evolution and function of these kinds of relationships in humans and other primates. See Silk 2003 2007

The structure and function of female bonds

I have studied baboons in Amboseli, Kenya (1982-3; 1998-present) and the Okavango Delta, Botswana (1992-4). . In Botswana, Robert Seyfarth, Dorothy Cheney, and I studied how females used grunts to reconcile conflicts and regulate social interactions. I returned to work in Amboseli in 1998 to study the structure and adaptive value of social bonds among adult females in collaboration with Jeanne Altmann and Susan Alberts. We also studied paternal kin recognition. For results of some of these analyses see Buchan et al. 2003, Silk et al. 2003, 2004, 2006a, 2006b