Susan Perry: UCLA Department of Anthropology

Recently, 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 “culture” 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 “culture” 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.