Play behavior in immature moor macaques (Macaca maura) and Japanese macaques (Macaca fuscata).

Play is widespread across mammalian taxa, but species strongly vary in the ways they play. In less despotic primate species (i.e., with less steep dominance hierarchies, less severe conflicts, and more reconciliation), play has been described as being more frequent, cooperative, and freely expressed. To study the link between social play and dominance style, we compared play behavior in free-ranging infants, juveniles and subadults of more despotic Japanese macaques (Macaca fuscata, N = 24) and less despotic moor macaques (Macaca maura, N = 17). We found interspecific differences in play behavior that corresponded with the contrasting dominance styles of the study species, largely confirming our predictions. In particular, moor macaques spent a larger proportion of time in solitary and social play than Japanese macaques, while Japanese macaques spent a larger proportion of time in grooming interactions. In moor macaques, play sessions included more players, a larger variety of play behaviors, greater play face rates, a greater proportion of time in contact play, and a higher rate of reciprocal play-biting than in Japanese macaques. Aggressive escalations were not common, but more frequent in Japanese macaques. Finally, a higher frequency of play faces during play sessions predicted the occurrence of more reciprocal play-bites, but not the proportion of time spent in contact play behaviors. Additional studies on other groups and species will allow a better understanding of the link between dominance style and social play.