Monkeys are having gay sex all the time, study finds

Male monkeys regularly have gay sex and are “behaviourally bisexual”, according to researchers at Imperial College London.

It found that same-sex sexual behaviour among monkeys made them better friends, and more likely to back each other up in conflicts.

A new study, published in Nature Ecology & Evolution, focused on 236 males within a wild colony of 1,700 rhesus macaques on a Puerto Rican island over three years.

The findings suggest that “same-sex sexual behaviours” (SSB) have evolved and could be a common feature of primate reproduction, challenging beliefs that this is rare in non-human animals.

SSB-engaging monkeys also had more offspring, the Independent reported.

More specifically, with all social mountings of the 236 males recorded (male-on-male and male-on-female), 72 per cent engaged in same-sex mounting compared with 46 per cent different-sex mounting.

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Jackson Clive, from Imperial’s Georgina Mace Centre for the Living Planet, who worked on the study, said they found “most males were behaviourally bisexual”.

He added: “Variation in same-sex activity was heritable. This means that the behaviour can have an evolutionary underpinning: for example, we also found that males that mounted each other were also more likely to back each other up in conflicts. Perhaps this could be one of many social benefits to same-sex sexual activity.”

He hoped the results would encourage further discoveries.

Lead researcher, professor Vincent Savolainen, said their mission was to “advance scientific understanding of same-sex behaviour, including exploring the benefits it brings to nature and within animal societies”.

Same-sex behaviour ‘benefits’ societies

He highlighted how “more than two-thirds displayed same-sex behaviour and this strengthened the bonds within the community”.

The professor went on: “Unfortunately, there is still a belief among some people that same-sex behaviour is unnatural, and some countries sadly still enforce the death penalty for homosexuality.

“Our research shows that same-sex behaviour is in fact widespread among non-human animals.”

“Our mission is to advance scientific understanding of same-sex behaviour, including exploring the benefits it brings to nature and within animal societies.”

SSB has been observed in thousands of different animals. There are a range of theories as to why but little data to support any of them.