Behavioral mimicry predicts social favor in adolescent rhesus macaques (Macaca mulatta)

Non-conscious mimicry is a highly conserved component of animal behavior with multifaceted connections to sociality across taxa. One intriguing consequence of this mimicry in primates is that it promotes positive social feedback from the recipient toward the mimicker. This suggests that mimicry in primates may be an important aspect of positive social interaction, but few studies have tracked the consequences of mimicry in naturally occurring complex social conditions. Here, we designed a novel ethogram to characterize mimicry between conspecifics, to better understand whether mimicry is associated with affiliation between primates in a semi-naturalistic captive setting. In this study, 15 juvenile (aged 2-4 years) rhesus macaques (Macaca mulatta) were observed at the California National Primate Research Center. Frequencies of mimicry defined a priori (e.g. following, postural mimicry) were observed over a course of 12 weeks. In separate observations during the same period, focal social behavior (e.g. aggression, play, affiliation) with group members was also observed. Subjects that exhibited higher degrees of mimicry were not more prosocial, but they received significantly more play overtures from social partners (p < 0.01). Additionally, rates of mimicry were higher in 2- and 3-year-olds than 4-year-olds. These results provide proof of principle in a small sample of monkeys that mimicry is associated with social advantages in a complex, semi-naturalistic setting in primates.