Simple acts of friendly physical contact before feeding help bonobos and chimpanzees reduce conflict and share food more peacefully, according to a new study that sheds light on the evolutionary roots of cooperation and human social behavior.
Researchers observed 116 bonobos and chimpanzees living in semi-wild sanctuaries in the Democratic Republic of the Congo and Zambia to examine how the animals behaved just before receiving food.
In their findings published in Proceedings of Royal Society B, the researchers discovered that brief gestures such as hugging, touching, holding hands and other forms of friendly contact increased the likelihood that the apes would tolerate one another while feeding instead of competing aggressively.
“Increased contact affiliation prior to a competitive feeding event promotes group-level social tolerance in our two closest ape relatives, bonobos and chimpanzees,” researchers found.
Furthermore, the study also revealed that reassurance followed species-specific social patterns.
Comparatively, female bonobos were more likely to exchange friendly contact with other females, while male chimpanzees most often reassured fellow males before feeding. These interactions researchers said appeared to strengthen social bonds and improve cooperation when competition over food was expected.
However, not all groups behaved the same. The study observed that more socially tolerant groups benefited most from these reassuring behaviors, while one less tolerant chimpanzee group showed the opposite trend, suggesting that existing social tensions can influence whether friendly contact successfully reduces conflict.
“Pre-emptive affiliative contacts act as a short-term mechanism to promote social tolerance and mitigate competition.” the researchers said.
Additionally, researchers found that chimpanzees perform highly trusting behaviors, including gently kissing another chimpanzee’s body or placing a hand or finger inside another’s mouth. These vulnerable actions were much more common in the most peaceful chimpanzee group, indicating they may serve as powerful signals of trust and cooperation.
The findings suggest that reassuring physical contact has deep evolutionary origins and likely existed long before modern humans evolved.
Scientists believe these behaviors helped ancient ancestors manage competition, strengthen relationships and maintain stable social groups.
The researchers said the findings also provide valuable insight into human behavior.
“Understanding these mechanisms in non-human apes provides important insights into the evolutionary foundations of human sociality.” The study noted.
The researchers added that simple gestures of reassurance are more than signs of affection—they are practical tools that help build trust, reduce tension and encourage peaceful cooperation among our closest living relatives, offering fresh clues about the origins of human social life.
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