Sexual behavior in animals is often associated with reproduction. However, according to research, it also serves important social functions. A study conducted by Durham University and published in Royal Society Open Science provides new insights into how bonobos and chimpanzees use sexual behavior to manage social tensions. Nevertheless, by comparing these behaviors in two of our closest primate relatives, findings shed light on how sex may have played a similar role in early human societies.
Beyond Reproduction: Bonobos and Chimps Offer Clues to How Our Early Ancestors Had Sex Not Just for Reproduction But for Social Purpose
Background
Bonobos or Pan paniscus and chimpanzees or Pan troglodytes are genetically similar but exhibit distinct social behaviors. Bonobos are well known for their frequent sexual interactions. These are thought to promote cooperation and reduce aggression. Chimpanzees, on the other hand, have been traditionally viewed as more aggressive. These creatures often depend on other social strategies for resolving conflicts.
However, until the aforementioned research, a direct comparison between these two species in similar environments had not been conducted. The researchers set out to examine whether both species use sex to ease social tension and how their behaviors compare in two specific contexts: post-conflict interactions and pre-feeding social dynamics.
The study took place at two African great ape sanctuaries. These were in the Lola ya Bonobo Sanctuary in the Democratic Republic of Congo and Chimfunshi Wildlife Orphanage Trust in Zambia. The researchers observed 53 bonobos and 75 chimpanzees over seven months in 2019 for a total of 1400 hours. They analyzed behaviors occurring after conflicts and before feeding. These two are known to provoke social stress.
Findings
• Bonobos and chimpanzees both use sexual behavior to manage social tension. This supports the idea that their last common ancestor with humans also exhibited this trait in social interactions.
• Note that bonobos engage in sexual behavior more frequently after conflicts. They use it to repair social bonds, while chimpanzees rely more on other behaviors like body contact and gestures of reassurance.
• Further findings indicate that both species exhibit similar sexual behavior before feeding. This suggests that sex is a shared strategy for reducing tension when competition and power dynamics arise.
• Female bonobos and male chimpanzees are the most frequent initiators of pre-feeding sexual interactions. This pattern indicates sex-based differences in how the two species use particular social strategies.
• Older individuals in both species have higher tendencies to initiate sexual interactions before feeding. This suggests that the behavior may be learned over time and passed down through generations.
• The researchers also observed that sexual behavior occurs in both heterosexual and homosexual pairings. This reinforces its function as a tool for social bonding rather than being purely for reproduction.
• Chimpanzees, despite being traditionally seen as more aggressive, still use sex significantly for stress management. This challenges the idea that only bonobos rely on sexual behavior for conflict resolution.
• The researchers noted that their findings contribute to understanding human evolutionary history. The findings suggest that early humans also used sex beyond reproduction, likely for social cohesion.
Implications
The implications of the aforementioned findings extend beyond bonobos and chimpanzees. Human societies also exhibit behaviors where sex plays roles beyond reproduction. These include fostering social bonds and reducing tension.
Nevertheless, by understanding how our closest relatives use sexual behavior to navigate social challenges, scientists gain valuable insights into the evolutionary roots of human sexuality. The findings support the idea that the use of sex for social bonding and conflict resolution was likely an integral part of early human social structures.
The study challenges outdated stereotypes and provides a more nuanced understanding of primate social strategies by bridging the gap between bonobo and chimpanzee behavior. It reinforces the idea that human sexuality, like that of close primate relatives, is deeply intertwined with social interactions and evolutionary history.
Additional studies could further illuminate the complex ways in which sex has shaped the social dynamics of primates. Others can explore how these behaviors manifest in wild populations and whether additional environmental factors influence the social role of sex in great apes.
FURTHER READINGS AND REFERENCES
- Brooker, J. S., Webb, C. E., Van Leeuwen, E. J. C., Kordon, S., De Waal, F. B. M., and Clay, Z. 2025. “Bonobos and Chimpanzees Overlap in Sexual Behavior Patterns During Social Tension. In Royal Society Open Science. 12(3). The Royal Society. DOI: 1098/rsos.242031