Affiliative and submissive communication in rhesus macaques

This study analyzed the occurrence of selected facial expressions, gestures, and postures, in relation to sex and rank of sender and receiver, context, and responses elicited in a large multi-male multi-female group of rhesus macaques (Macaca mulatta) living in captivity. The group was observed for 100 hr during the mating and the birth season. Data were collected with the behavior sampling method. The bared-teeth display and the hindquarter presentation were the most prominent signals in the rhesus submissive and affiliative repertoire. Both signals were primarily displayed in response to aggression and approaches; bared-teeth in response to approaches from the front, presentation in response to approaches from the rear. Lip-smack had a submissive component like bared-teeth and presentation but was more likely to be displayed by approaching individuals and followed by affiliation than these behaviors. The distribution of hip-touch and mount was different from that of bared-teeth, presentation, and lip-smack, these behaviors mostly occurring between males, irrespective of their dominance rank. Other infrequent signals and behavioral sequences were limited to specific male-female and mother-infant interactions.