Same-sex sexual behaviour among non-human primates may help strengthen social bonds and maintain group stability during environmental and social stress, according to new research. The study, published in Nature Ecology & Evolution, analysed reports from 59 primate species, including chimpanzees, Barbary macaques and mountain gorillas. Researchers found the behaviour was widespread and more common in species living in harsh, dry environments with scarce resources and higher predation risks.
The research team, led by scientists from Imperial College London, suggests the behaviour can reduce tension, limit aggression and reinforce cooperation within complex social groups. Co-author Vincent Savolainen said the findings imply either a deep evolutionary origin or repeated independent evolution across primates. The study also found higher rates in longer-living species and those with pronounced size differences between sexes, traits linked to intense social competition.
While the authors caution against directly applying the findings to humans, they note early human species may have faced similar pressures. Independent experts said the study highlights same-sex behaviour as a normal and adaptive part of primate social life, though others warned against oversimplifying or extrapolating animal behaviour to human sexuality.
