Monkeys sometimes have 'pets' like humans

A comprehensive review of 303 documented cases across scientific literature, primatologist surveys, and media accounts found that monkeys and apes regularly form bonds with other species—grooming, playing, adopting, and caring for animals outside their own kind, from langurs petting squirrels to capuchins raising infant marmosets.

These observations suggest evolutionary building blocks of empathy and social flexibility; the study does not equate primate behavior directly to human pet ownership.