Could sex be more than just reproduction – for chimps and bonobos too? We’ve long known that physical intimacy in humans can defuse tension, mend rifts, and build bonds. But are we the only primates using pleasure as a peacekeeping tool? New research dives deep into the post-conflict behaviours of our closest relatives, revealing surprising parallels between how humans and the great apes use sex – and a few intriguing differences too. These insights may change the way we see the origins of human sexuality.
Humans often hug, kiss, and touch after arguments. We have long understood that sex is about more than just reproduction. Throughout history and across cultures, it has helped us express intimacy, build stronger bonds, and navigate social power dynamics. However, the question remains: do our closest animal relatives, such as bonobos and chimpanzees, also utilise sex for purposes beyond mere mating? Insights into the sexual lives of our primate cousins could shed fascinating light on the evolutionary origins of this uniquely human trait.
New research published in Royal Society Open Science offers insight into the way these great apes use sex. Researchers from Durham University’s Department of Psychology spent over 1,400 hours observing chimpanzees at the Chimfunshi Wildlife Orphanage Trust in Zambia, and bonobos at the Lola ya Bonobo sanctuary in the Democratic Republic of Congo.
Lola ya Bonobo houses three groups of bonobos in enclosures that vary in size from 15 to 20 hectares, featuring rainforest, swamp, lake, stream, and open grass areas. Chimfunshi houses four groups of chimpanzees in enclosures ranging from 19 to 77 hectares, set within miombo woodland. Both sanctuaries are home to wild-born individuals, as well as those orphaned and rescued from the pet and bushmeat trades, and animals born within the sanctuaries. In both environments, the animals can roam and forage independently, but a team provides them with fruits and vegetables twice a day.
Lead researcher Jake Brooker explained that they observed spontaneous fights and followed the victims, recording all their social interactions, both with uninvolved group members and with the individuals they had fought. The team also conducted a feeding experiment to create a competitive situation, allowing them to observe how group members behaved when tensions were high.
Bonobos and chimpanzees are valuable to study because they are our closest living relatives. While chimpanzees are often the stars of evolutionary theories, bonobos share around 98.7% of their DNA with humans, just like chimps. There are some key differences between the species. Female coalitions and their sons lead bonobo societies, whereas alpha males and their male allies lead chimpanzee groups.
This backdrop of contrasting social structures fuelled the researchers’ expectations. Bonobos have a reputation as the “make love, not war” apes, so the research team expected to see significant differences between the two species. Brooker noted they expected bonobos to use sexual behaviours, like genital contact, more often after conflicts or during feeding competition. While they knew chimps did this too, they did not expect it to happen as frequently as it did, and the extent of the overlap surprised them.
The study revealed that while bonobos were more likely to use genital contact after conflict, both species showed similar rates of this behaviour before feeding when competition for resources intensified. “We did think male-male chimp pairs might use sex more than other chimp pairs, but the tendencies were still reasonable across all pairs in both species,” says Brooker.
Interestingly, female bonobos and male chimps were more likely to initiate these interactions, hinting at sex-specific roles in social bonding. Female-female bonobo pairs were the most frequent users of sexual behaviours, while it was predominantly male-female pairs in chimps, usually initiated by the males. However, sexual contact occurred across all pairings.
What stood out most was how these great apes used genital contact in anticipation of feeding competition. They also found that group differences influenced the frequency of these interactions. While age did not affect this post-fight sexual action in either species, older apes were more likely to initiate sex before feeding. This suggests that it may be a learned behaviour passed down over time.
The researchers believe that these sexual interactions serve a critical social function: conflict resolution and tension reduction. In stressful situations, genital contact can help calm individuals, strengthen bonds, and prevent fights from escalating. This aligns with findings from human research, which indicate that physical intimacy can reduce stress and foster social connections. In bonobos and chimpanzees, sexual contact may serve as a signal of reconciliation or a means to maintain harmony within the group.
The study challenges the idea that only humans use sex for complex social reasons and suggests that this is an ancient primate trait, suggesting that our last common ancestor with these great apes likely used sex for purposes beyond mere reproduction. The researchers argue that the social role of sex is not a uniquely human construct, but rather an ancient and flexible trait passed down through our shared evolutionary lineage.
As scientists continue to unravel the social intricacies of these great apes, their intimate behaviours offer a compelling window into the origins of human sexuality and social dynamics. The secret lives of our primate cousins may hold the key to understanding some of our most fundamental social instincts.
Resources
Brooker JS, Webb CE, van Leeuwen EJC, Kordon S, de Waal FBM, Clay Z. 2025. Bonobos and chimpanzees overlap in sexual behaviour patterns during social tension. R. Soc.Open Sci. 12: 242031.
Further reading
- Discover how new research reveals striking similarities between chimpanzee and human communication, deepening our understanding of primates
- Celebrating chimpanzees: Check out this gallery of fantastic images of chimpanzees – in honour of our fellow great ape
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