Same-sex sexual behaviour among non-human primates may help reinforce social bonds and maintain group stability during periods of environmental or social stress, according to new research. Scientists analysed documented behaviour across 59 primate species, including chimpanzees, Barbary macaques and mountain gorillas, and found it to be widespread rather than exceptional. The study, led by researchers including Prof Vincent Savolainen of Imperial College London, was published in Nature Ecology & Evolution.
The analysis found such behaviour was more common in species living in harsher, drier environments with scarce resources and higher predation risk. It was also associated with longer lifespans, greater size differences between males and females, and complex social hierarchies, all factors linked to intense social competition. Researchers suggest same-sex behaviour may reduce tension, strengthen bonds and help groups navigate challenging conditions. While cautioning against direct comparisons with humans, the authors note early human species likely faced similar pressures. Independent experts said the findings highlight the adaptive role of same-sex behaviour in primate societies, while stressing that human sexuality remains far more complex and should not be simplistically inferred from animal studies.
