A 491-species comparison links documented same-sex sexual behavior in primates with ecological pressure, long life histories and complex social systems, while leaving substantial room for underreporting and multiple evolutionary mechanisms.
A survey of 491 primate species found same-sex sexual behaviour was most likely in long-lived animals facing food scarcity, predation pressure and complex social hierarchies — evidence that the behaviour is shaped by ecology and social life rather than a single evolutionary cause
Natural History