Turns out gay sex might have evolutionary benefits after all, study finds

A new study says a large number of male macaque monkeys engage in homosexual activity. In fact, they’re more likely to engage in sexual behavior with other males than with females.

The scientists at Imperial College London are exploring the potential evolutionary benefits of same-sex sexual behavior. They studied a colony of macaque monkeys in Puerto Rico over three years. The results have just appeared in Nature Ecology and Evolution.

Many homophobes are fond of claiming that homosexuality is unnatural. In truth, same-sex sexual behavior and coupling have been observed in many different animal species. And it’s not just when there’s a lack of potential mates of the opposite sex.

This study looked at 236 males within a colony of 1,700 rhesus macaques living on one of Puerto Rico’s islands. Researchers recorded all the social mountings these male monkeys participated in. They also did genetic analysis and tracked their parentage and pedigree.

“We found most males were behaviorally bisexual”

The perhaps surprising result was that 72% of males engaged in same-sex mounting, in comparison with 46% for different-sex mounting.

“We found most males were behaviorally bisexual, and that variation in same-sex activity was heritable,” said the study’s lead author, Jackson Clive.

“This means that the behavior 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.”

Having support and back-up from, well, friends-with-benefits, seems to benefit monkeys competing in a group for social status.

They also found, again perhaps surprisingly, that males that engaged in same-sex behavior (SSB) “may be more successful in reproducing, potentially due to the benefits provided by more coalitionary bonds.”

In terms of hereditary traits, they said that engaging in same-sex behavior seemed to correlate in the same way that other behaviors appear to have some hereditary aspects, such as grooming and sociality.

They observed that whether the monkeys were “mounters” or “mountees” (er, tops or bottoms), bore no correlation to their social standing in the group. In other words, it had little to do with them exerting dominance. Instead, there was a genetic correlation in the traits.

“Same-sex behaviour widespread amongst non-human animals”

The researchers said people should not be quick to draw comparisons between monkeys and humans, despite them being close relatives on the evolutionary tree. However, the study confounds the notion that same-sex behavior only occurs in humans.

Lead researcher Professor Vincent Savolainen, Director of the Georgina Mace Centre for the Living Planet at Imperial, said in a press release: “Unfortunately there is still a belief amongst some people that same-sex behavior is ‘unnatural,’ and some countries sadly still enforce the death penalty for homosexuality. Our research shows that same-sex behaviour is in fact widespread amongst non-human animals.

“Our mission is to advance scientific understanding of same-sex behavior, including exploring the benefits it brings to nature and within animal societies. Amongst the macaques we looked at in this study, more than two-thirds displayed same-sex behavior and this behavior strengthened the bonds within the community.”

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