Asymmetries in grooming interactions between juvenile and adult female wedge-capped capuchin monkeys

Abstract

Abstract. Motivation for participation in social grooming differs for juvenile and adult primates in female-bonded social systems; juveniles attempt to develop social relationships as a means of integration into the group, whereas adults attempt to maintain relationships with other adults. Juveniles should therefore seek grooming relationships with adults but adults should be relatively uninterested. The local resource competition hypothesis predicts that grooming relationships between adults and juveniles should occur primarily within matrilines and should be negatively correlated with aggressive interactions. Alternatively, grooming relationships may depend on the ability of juveniles to provide additional services, such as assistance in aggressive interactions and allomaternal care. Grooming interactions of juvenile and adult female wedge-capped capuchin monkeys, Cebus olivaceus, were predictably asymmetric. Juveniles approached and groomed more than adults, whereas adults terminated grooming sessions more and often failed to reciprocate grooming. Juvenile-adult grooming was inconsistent with patterns predicted by the local resource competition model. Dyads of closely related females did not groom more than unrelated dyads and there was no relationship between rates of grooming and aggression. Frequency and duration of grooming was significantly correlated with frequency of allomaternal care given by juveniles. Frequency of grooming also correlated with rates of alliance formation by adults and juveniles. Juveniles provided agonistic support during alliances twice as often as adults supported juveniles. The structure of grooming indicated that juveniles were the primary beneficiaries of grooming relationships with adults. Juveniles provided grooming services to adults and provided additional benefits of allomaternal care and agonistic support during aggression. In return, juveniles were integrated into the adult social structure in the group.