Overview
- Published in Nature Ecology & Evolution, the peer-reviewed analysis surveyed prior research on 491 nonhuman primate species and documented same-sex sexual behavior in 59 of them with repeated occurrences in 23.
- The cataloged behaviors included mounting, genital touching, ventral contact and fellatio, and the study counted both male–male and female–female interactions while excluding nonsexual social contact.
- Statistical patterns associated the behavior with harsher or drier habitats, higher predation risk, resource competition, pronounced sexual dimorphism, longer lifespans and more complex social hierarchies.
- The authors propose that same-sex behavior can serve flexible social functions such as tension reduction, alliance building and bond reinforcement, describing it as a social currency used within competitive groups.
- Researchers emphasize data gaps and likely underreporting, outline targeted follow-up tests in macaques to evaluate fitness effects and caution against applying these findings to human sexual orientation or using them for political claims.