Same-sex sexual behaviour among non-human primates may help reinforce social bonds and maintain group cohesion during times of environmental or social stress, according to new research. Writing in Nature Ecology & Evolution, scientists led by researchers at Imperial College London analysed reports across 59 primate species, including chimpanzees, Barbary macaques and mountain gorillas, finding the behaviour to be widespread.
The study suggests such behaviour is more common in species living in harsher, drier environments with scarce resources and higher predation risks. It was also linked to longer lifespans, pronounced size differences between males and females, and complex social hierarchies, all factors associated with intense social competition. Vincent Savolainen said the findings support the idea that same-sex behaviour can reduce tension, increase bonding and help groups navigate challenges. Lead author Chloe Coxshall added that while there is a heritable component, environmental influences play an important role.
The researchers cautioned against direct comparisons with humans but noted the findings raise broader questions about social pressures and behaviour. Independent experts welcomed the study’s contribution while stressing that human sexuality remains far more complex and should not be directly inferred from animal behaviour.
