Behaviours once thought uniquely human, such as kissing and embracing to ease tension, appear deeply rooted in our primate past. A study from Durham University published on 22 July 2026 shows that chimpanzees and bonobos routinely use reassuring body contact before competitive feeding events, and those that do so spend more time sharing food without conflict.
The researchers filmed more than 10 hours of footage from 116 semi-wild apes living in sanctuaries. They created controlled tension by swinging peanuts into a restricted space, mimicking the scramble for limited resources that occurs naturally around fruiting trees. Individuals and groups that engaged in more pre-feeding touching, hugging and kissing went on to cofeed more peacefully.
Patterns differed between species in ways that match their known social structures. Among bonobos the strongest effect appeared in female-female pairs. In chimpanzees it was clearest among males. The link between reassurance and tolerance proved most pronounced in the more socially tolerant groups of both species.
Before stressful events, they come together, they reassure each other, they touch each other, they hug each other. It is like a we rather than a me.
Prof Zanna Clay, one of the researchers, described the pattern in those terms. Chimpanzees, especially males in tolerant groups, took the trust further by placing fingers or hands in each other’s mouths. The team also recorded sequences in which multiple animals joined embraces one after another, a behaviour they termed reassurance trains.
Dr Jake Brooker, lead researcher, recalled the moment that inspired the work. One male embraced another from behind, then a second joined, then a third, until a whole chain settled. The observation prompted systematic study of these proactive gestures rather than the post-conflict consolation documented in earlier primatology.
The similarity across bonobos and chimpanzees suggests these reassurance behaviours share an evolutionary origin dating back more than six million years to the common ancestor of humans and these apes. The paper, titled Reassuring body contact promotes social tolerance in bonobos and chimpanzees, appears in Proceedings of the Royal Society B.
