Updated

Updated · IFLScience · Jul 31

Review Finds 303 Primate Cross-Species Bonds, Pointing to Roots of Human Pet-Keeping

Updated

Updated · IFLScience · Jul 31

Review Finds 303 Primate Cross-Species Bonds, Pointing to Roots of Human Pet-Keeping

Q: Why did a marmoset live with capuchins for over a year, and what does that reveal about the evolutionary roots of pet-keeping?

The marmoset likely stayed with the capuchins because two adult female capuchins accepted it and sustained that care long after the initial encounter. In the best-documented case, the infant marmoset, Fortunata, was first carried by a female capuchin named Chiquinha in Brazil in 2004. When Chiquinha became pregnant, another female, Dendê, took over. Fortunata then traveled, foraged and socialized with the troop for about a year to 14 months, and even juveniles adjusted their play so they would not injure the much smaller animal. Researchers cannot say with certainty whether this began as adoption, abduction or simple curiosity, because animal intent is hard to prove. But several factors appear to have helped the bond persist: capuchins are strongly attracted to infants, they tolerate close physical contact, the marmoset was small and able to remain near them, and the group lived in conditions where food access may have reduced the costs of caring for another species. What this reveals is not that primates keep pets in the human sense. Rather, it suggests that some of the traits that make pet-keeping possible in humans—curiosity about other species, social tolerance, caregiving, play and the ability to maintain long-term cross-species bonds—were already present in other primates. That is why researchers describe cases like Fortunata’s as the closest known examples of “proto-pet-keeping,” pointing to deep evolutionary roots for human-animal companionship.

3 articles · Updated · IFLScience · Jul 31

A new review in Primates compiled 303 documented cases of primates socially interacting with other species, plus 58 photos or videos and a survey of 66 primatologists.
The analysis found primates most often bonded with closely related species, supporting the idea that shared signals and behavior make cross-species contact easier and safer.
Females were more likely than males to groom other animals, while juveniles were significantly more likely to play across species boundaries; no age bias appeared in nurturing behavior.
The documented interactions ranged from grooming, carrying and play to abusive or fatal encounters, suggesting cross-species sociality is widespread but not uniformly benign.
Grueter said these behaviors are not pet-keeping itself, but may be evolutionary building blocks of human-animal companionship and could help zoos and sanctuaries manage mixed-species groups.