Paternal relatedness and age proximity regulate social relationships amongadult female rhesus macaques

Kin selection promotes the evolution of social behavior that increases the survival and reproductive success of close relatives. Among primates, mater nal kinship frequently coincides with a higher frequency of grooming and ag onistic aiding, but the extent to which paternal kinship influences adult f emale social relationships has not yet been investigated. Here, we examine the effect of both maternal and paternal kinship, as well as age proximity, on affiliative interactions among semifree-ranging adult female rhesus. ma caques, Macaca mulatta. Kinship was assessed by using both microsatellites. and DNA-fingerprinting. Our study confirms that the closest affiliative re lationships characterize maternal half-sisters. We provide evidence that ad ult females are significantly more affiliative with paternal half-sisters t han with nonkin. Furthermore, paternal kin discrimination was more pronounc ed among peers than among nonpeers, indicating that age proximity has an ad ditional regulatory effect on affiliative interactions. We propose that kin discrimination among cercopithecine primates emerges from ontogenetic proc esses that involve phenotype matching based on shared behavioral traits, su ch as inherited personality profiles, rather than physiological or physical characteristics.