Monkey friendships with dogs, deer and even pigs offer clues to the evolutionary origins of pet-keeping
A new study from the University of Oxford analyzes hundreds of cases of cross-species social interactions among non-human primates. The research suggests that behaviors like grooming and play between different species may provide evolutionary insights into why humans keep pets.
Why it matters
Understanding the evolutionary roots of interspecies companionship helps explain the biological and psychological foundations of the human-animal bond.
edited by Lisa Lock , reviewed by Robert Egan
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Add as preferred source Examples of affiliative interspecific interactions involving non-human primates. Credit: Primates (2026). DOI: 10.1007/s10329-026-01281-0 Why do humans keep pets? A new international study suggests that some of the behavioral foundations of human-animal companionship may have much deeper evolutionary roots than previously thought.
Researchers from the University of Oxford and collaborators around the world have compiled the first comprehensive review of friendly interactions between nonhuman primates and other species. The study documents 427 cases involving 88 primate species and 127 partner species, 55 of them nonprimates, revealing that monkeys and apes frequently play, groom, hold, carry and even adopt individuals from other species.
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