What primates tell us about the evolutionary origins of keeping pets — SkimNews
SkimNews Take
Cross-species social tolerance in wild primates implies the underlying capacity for attachment across species lines is an ancient, conserved trait—meaning human pet-keeping is less a cultural innovation than an inherited behavioral tendency redirected into a domesticated niche.
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- Cyril Grueter of the University of Oxford published a synthesis study in the journal Primates on 21 July documenting 427 cases of primates interacting affiliatively with members of other species.
- The team documented 88 primate species engaging socially with 127 non-primate species, with 311 instances from the wild and 111 from captivity — confirming the behaviour isn't an artefact of captivity.
- Play (139 cases) and grooming (136 cases) were the most frequently reported interaction types, with Old World monkeys pairing with dogs (24 cases) the second most common cross-species match.
- Males handled heterospecifics roughly, and the team confirmed 13 deaths of heterospecifics (seven birds, three primates, two pangolins, one domestic cat), while juveniles and females were the most likely to engage cross-species.
- Grueter's interest began ~20 years ago at a Shanghai zoo when he observed a gibbon caressing a mouse, followed by field observations of black-and-white snub-nosed monkeys jumping on domestic pigs in China.
- Most interactions lasted minutes to hours, ruling out pet-keeping — but a marmoset adopted by wild capuchins for at least 10 months represents what Grueter calls 'a rudimentary form of pet-keeping behaviour.'
Why it matters: With 311 of 427 interactions occurring in the wild, the study reframes cross-species bonding as a deep primate trait rather than a modern cultural invention, giving researchers a baseline for understanding how humans first formed relationships with animals tens of thousands of years before domestication.
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