Study Shows Same-Sex Sexual Behavior is Widespread and Heritable in Macaque Monkeys
Published:03 Aug.2023 Source:Imperial College London
Observations of a wild colony of macaques over three years show same-sex sexual behaviour among males is widespread and may be beneficial. The results, published today in Nature Ecology and Evolution, suggest same-sex sexual behaviour (SSB) has evolved and may be a common feature of primate reproduction.
The team studied 236 males within a colony of 1,700 rhesus macaques living freely on the tropical island of Cayo Santiago, Puerto Rico. As well as observing their behaviour and conducting genetic analyses, the team had access to pedigree records, which detail parentage of each individual back to 1956. The team also analysed whether SSB was heritable. Using the pedigree data, they found SSB in males was 6.4% heritable, which provides the first evidence of a genetic link to primate SSB outside of humans. This figure is similar to other heritable behaviours in primates, such as grooming and sociality.
The results suggest some degree of SSB can evolve adaptively, depending on the context, and so may be a common feature of primate reproductive ecology. There are many examples of other primate groups engaging in different forms of SSB, so further in-depth genetic studies could strengthen this conclusion.