Same-sex sexual behaviour in non-human primates may play an important role in reinforcing social bonds and maintaining group cohesion during periods of environmental or social stress, researchers suggest. Writing in Nature Ecology & Evolution, scientists from Imperial College London analysed reports across 59 primate species, including chimpanzees, Barbary macaques and mountain gorillas, finding the behaviour to be widespread. The study indicates such interactions are more common in species living in harsher environments with scarce resources, higher predation risk and complex social hierarchies.
The researchers found the behaviour was also associated with longer lifespans, pronounced size differences between sexes and intense social competition, all traits linked to larger, more structured groups. Lead author Chloe Coxshall said both genetic and environmental factors appear to shape the behaviour, which may help reduce tension, aggression and conflict. Co-author Prof Vincent Savolainen noted that early human species likely faced similar pressures, though the team cautioned strongly against direct comparisons with modern human sexuality. External experts welcomed the findings as evidence that same-sex behaviour is a common and adaptive feature of primate social life, while stressing that human sexual behaviour remains far more complex and should not be oversimplified.
