Thu October 11, 2012
Dr. Susan Perry, University of California Los Angeles – Benefits of Social Stability
In today’s Academic Minute, Dr. Susan Perry of the University of California Los Angeles explores how early stability can shape the adult lives of social creatures.
Susan Perry is a professor of anthropology at the University of California Los Angeles. Her research examines social relationships, social cognition, and communication among wild capuchins and macaques. In 1990 she founded the Lomas Barbudal Monkey Project for the purpose of studying social intelligence in the white-faced capuchin. She holds a Ph.D. from the University of Michigan.
Dr. Susan Perry – Benefits of Social Stability
For the past 22 years, I’ve been studying a population of wild capuchin monkeys in Costa Rica. One of my discoveries is that stable, peaceful childhoods dramatically improve male monkeys’ chances of breeding success later in life.
Capuchin females stay with their relatives for their entire lives, but adolescent males must leave their group and try to take over neighboring groups. Sometimes they leave alone, but usually they embark on this adventure with male friends or relatives.
Male takeovers are difficult for everyone. First, the incoming males challenge the alpha, or highest-ranking, male, and these fights generally result in serious wounds or even death. After a takeover, the new alpha male tries to kill the nursing infants fathered by the defeated males so that he can start breeding.
Sometimes, years go by without any male maintaining firm control over a group and there is constant violence. In other cases, an alpha male successfully holds his position for up to 18 years and is father or grandfather of almost all offspring born in the group. During stable periods, infant survival rates are high and the group grows.
Capuchin males have very different life outcomes depending on whether they’ve grown up in a stable group or one with much violence. Males who grow up in stable groups have more play partners, more half brothers with the same father, and more buddies they can migrate with. Males who migrate with friends or close relatives have a better chance of taking over neighboring groups than males who migrate alone. Males whose father or grandfather is alpha male while they’re growing up tend to migrate at a later age, and are more likely to become alpha males themselves after migrating. All of these factors improve the breeding success of males who grow up in stable social groups with successful fathers.