Study reveals primates regularly bond with non-family animals, echoing human pet-keeping

A new systematic review of 427 documented cases shows that at least 88 primate species engage in social behaviours such as play and grooming with 127 non-primate species, both in the wild and in captivity.

A comprehensive review published by Springer examined 427 unique cases where primates interacted socially with animals outside their own groups. The dataset covered 88 primate species and 127 other species, recorded in both natural habitats (311 cases) and captive environments such as zoos (111 cases). Play and grooming dominated the behaviours observed, with 139 instances of play and 136 of grooming, highlighting a capacity for curiosity and social flexibility.

Age and sex influenced the patterns: infants and juveniles were most likely to initiate play, while adult females tended toward grooming and caregiving, and adult males were the least socially active. Although many interactions were friendly, some involved abduction or neglect, leading to injury or death, underscoring that not all cross-species contacts are beneficial. The authors argue that these widespread behaviours point to an ancient evolutionary foundation for the human practice of keeping pets and forming inter-species bonds.