UCLA

Anthropology has a long history of examining the important roles of kinship in human societies, and an important tool in that process has been the use of the comparative method. White-faced capuchin monkeys (Cebus capucinus) are an ideal model organism for comparison to human studies, because they share important similarities such as the presence of full siblings and multiple generations of kin within groups. Primate societies are highly structured – factors such as kinship, age, and dominance rank play crucial roles in determining how and at what frequencies individuals interact. This variation in turn has an impact on the strength of social bonds that develop between different individuals. Research on the mechanisms underlying inbreeding avoidance in capuchins can contribute substantially to our broader understanding of kin recognition and how its limits result in a wide diversity of social structures even within species. In this thesis, I draw upon behavioral, genetic, and hormonal data to study mechanisms of kin recognition, particularly in the context of inbreeding avoidance, in a wild population of capuchins living in or near the Lomas Barbudal Biological Reserve in Costa Rica. First, I show that capuchin infants have multiple potential cues available that can be used to detect close kinship and relatedness to group members: these being spatial proximity, age proximity, and male alpha status. Second, I show that inbreeding avoidance in capuchins is strongest between social partners related at the levels of father-daughter. Third, I provide evidence that early spatial proximity to group members is one of the mechanisms involved in inbreeding avoidance in capuchins.