Primates July 2018

'''Wu, C. F., Liao, Z. J., Sueur, C., Sha, J. C. M., Zhang, J., & Zhang, P. (2018). The influence of kinship and dominance hierarchy on grooming partner choice in free-ranging Macaca mulatta brevicaudus. Primates, 59, 377-384.'''

Grooming plays an important role in nonhuman primate social interactions. Previous findings suggest that partner choice for grooming is nonrandom, strategical, and primarily involving kin. However, the strict hierarchies present in nonhuman primate social groups present other factors that influence grooming partner choice. A model proposed by Seyfarth (1997) posits that with the exception of close kin, high-ranking members are the most preferred grooming partners due to the potential for reduced aggression and/or support. However, there have been debates surrounding the model in the literature. Wu et al. (2018) conducted a study designed to address the specific claims of the model in a population of rhesus macaques with four predictions: (1) there will be a kin preference for grooming partners among females, (2) higher-ranking members will receive more grooming than lower-ranking members during grooming interactions, (3) non-kin grooming will act to reduce aggression, and (4) grooming between non-kin will occur more often with adjacently ranked individuals. Support for all four predictions was found. The authors suggest that conflicting findings among studies of grooming partner choice may be due to a scarcity of available partners, to group size, to group dynamics, and to the number of kin present in any given group, and suggest that these factors be carefully considered in future studies.