: Like two peas in a pod? : the influence of personality homophily on female Japanese macaque (Macaca fuscata) friendships

Abstract

Social bonds in primates influence the cooperative interactions and thereby individual fitness. The determinants of close bonds include age, sex, rank, and kinship. In addition, increasing evidence shows that personality, particularly similarity in personality characteristics among partners, also known as personality homophily, is an important factor in bond formation. In Japanese macaques, kinship and sex are the main determinants of close bonds, reflecting the social structure of this despotic, nepotistic macaque species. However, whether and how these socio-ecological factors may constrain the significance of personality in determining bonding is unstudied. The aim of this thesis is to examine whether dyadic personality similarity influences female relationships in a group of semi-wild Japanese macaques.

I assessed several personality traits as well as an indicator of curiosity by the frequency of exploring enrichment and experimental devices. 159h of focal data was collected (5h/ind.) of 32 adult and adolescent semi-wild Japanese macaque females living in Affenberg Zoo, Landskron, Austria. Based on the results, the friendships of this group’s female Japanese macaques is determined by kinship, and personality homophily in sociability. The evidence is in accordance with the known social structure typical for the species and previous findings regarding personality homophily in primates.