Sex differences in learning the allocation of social grooming in infant stumptailed macaques

Among primates, the intense mother-infant bond provides offspring with a lengthy period for learning from an experienced and reliable demonstrator. Since adult life differs for females and males, the expertise of mother may not be equally useful to both sexes of infant, particularly with regard to social relationships. Here, we report on differences between infant female and male stumptailed macaques in learning how to allocate social grooming, using their mothers as demonstrators. Infant females were significantly more socially precocious than males, starting at early ages to groom mothers. Throughout their first year of life, daughters showed more instances of mirroring mothers' behaviour than sons did. In addition, while grooming on their own, grooming durations of daughters to specific partners was significantly concordant with time devoted by mothers to such recipients. We suggest that daughters learn from their mothers how to distribute grooming amongst social companions, while sons primarily use mother as a secure platform to initiate socializing. These results lend support to the idea that mirroring equates with learning and leads to reinforcement of innate propensities for gender roles in primates.

Affiliations: 1: Instituto Nacional de Psiquiatría Ramón de la Fuente, Ethology Department, Calzada México-Xochimilco 101, Col. San Lorenzo Huipulco, Tlalpan 14370, Mexico City, Mexico;, Email: rmc@imp.edu.mx; 2: Instituto Nacional de Psiquiatría Ramón de la Fuente, Ethology Department, Calzada México-Xochimilco 101, Col. San Lorenzo Huipulco, Tlalpan 14370, Mexico City, Mexico; 3: Behaviour and Evolution Research Group, Department of Psychology, University of Stirling, Stirling, UK