Arre, A. M., Horschler, D. J. 2021. Swimming and diving as social play in juvenile rhesus macaques (Macaca mulatta). Behaviour 158(6), 529-546.

Although play is ubiquitous throughout the animal kingdom, and in primates especially, the ultimate explanations and proximate mechanisms of play are not well understood. Previous research proposes that primate play may be important for the development of cognitive skills including executive function, emotional regulation, and impulse control, and could help to build social skills and network connections needed in later life. However, many of these hypotheses have not been thoroughly tested. Here, we report observations of novel play behaviour that could provide unique opportunities to explore these hypotheses: young rhesus macaques (Macaca mulatta) engaging in aquatic social play in a naturalistic setting. Based on our observations, we propose that aquatic play has social elements that make it ideal for testing ultimate explanations of primate play and hypotheses about the cognitive mechanisms that support it.