How primates use ‘make-up sex’ to ease social tensions

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Tensions can sometimes be eased under the duvet when couples argue, but we humans are not the only ones to use sex as an outlet for frustration. A British study, published in the journal Royal Society Open Science, reveals that bonobos and chimpanzees also resort to sex to ease tensions within their group.

Researchers at Durham University have been studying the sexuality of these primates, which is not limited to reproduction. Bonobos, in particular, are known for their sexual freedom and their tendency to use sex to strengthen social bonds. In chimpanzees, on the other hand, this function of sex remains less studied.

To better understand this behavior, the scientists observed these two species in sanctuaries in the Democratic Republic of the Congo and Zambia, at specific times of stress: after social conflicts and before feeding, a time when competition is strong. In total, more than 1,400 hours of observation were conducted on 53 bonobos and 75 chimpanzees, over a period of seven months.

The results show that, just before feeding, bonobos and chimpanzees adopt similar behaviors. They ease tensions without violence through sexual contact, often initiated by the older members. This practice seems to be learned over time, suggesting that it is passed on from one generation to the next.

After a conflict, however, their reactions differ. Bonobos prefer to reconcile through sex, while chimpanzees favor other forms of appeasement, such as affectionate gestures or reassuring contact.

Interestingly, in both species, these sexual interactions are not limited to opposite-sex couples: they can also take place between individuals of the same sex. In bonobos, it is the females who most often take the initiative, while in chimpanzees, this role tends to fall to the males.

Lead author Jake Brooker, a postdoctoral researcher in the Department of Psychology, Durham University, highlights the importance of these discoveries. He emphasizes that, although bonobos are often considered hypersexual and chimpanzees more aggressive, this research reveals that they take a similar approach by using sex to manage their social relationships.

“The fact that both species use sex in this way provides a fascinating window back in time, further evidencing that for humans, bonobos and chimpanzees, our use of sex for social reasons is something we have inherited from our common ancestor,” the researcher explains in a news release.

Nevertheless, it remains essential to observe this behavior in various contexts and in a natural environment in order to better understand the sexual and social mechanisms that govern the community life of our closest evolutionary cousins. By extension, this makes it possible to explore the very origins of human nature.

This study provides new insights into the deep connections between sexuality and social dynamics in our closest cousins. By revealing that sex plays a calming role in both bonobos and chimpanzees, it suggests that these behaviors could be a shared evolutionary legacy. A better understanding of these mechanisms could therefore help shed light on the origins of our own social and emotional interactions.