“These observations add orangutans to the list of primates that demonstrate homosexual behavior as part of their natural repertoire of social and sexual behavior,” said Dr. Fox. During her long-term study of orangutans in Sumatra, Dr. Fox observed only four orangutans demonstrating homosexual behavior, which indicates that the behavior is rare. All four were males, two of them sexually mature, and two adolescents. Dr. Fox also observed the two sexually mature males mate with adult females. Previously, homosexual behavior was only witnessed among captive orangutans or rehabilitated animals that have come in close contact with humans, according to the study. Other great apes also observed engaging in homosexual behavior include male mountain gorillas, female and male pygmy chimpanzees (bonobos), and humans.
Throughout the wild, orangutans – the only great ape native to Asia, besides man – are vanishing due to habitat loss, and poaching for the pet trade. Indonesia in particular has been the scene of rampant illegal logging of orangutan habitat, prompting some scientists to predict the species’ demise in the wild within ten years. “It’s disheartening that we’re only now beginning to learn of the full range of behavior among these highly intelligent animals, yet they are vanishing faster than any time in history,” Fox said.
American Journal of Primatology