Updates to our Terms of Use

We are updating our Terms of Use. Please carefully review the updated Terms before proceeding to our website.

Friday, March 29, 2024 | Back issues
Courthouse News Service Courthouse News Service

Genes linked to same-sex sexual behavior confer evolutionary advantage to humans, study finds

Scientists revealed in a new study Monday that genes associated with same-sex sexual behavior may be evolutionarily advantageous to humans, helping to improve reproduction.

(CN) — Scientists revealed in a new study Monday that genes associated with same-sex sexual behavior may be evolutionarily advantageous to humans, helping to improve reproduction.

In a study published in the journal Nature Human Behaviour, Brendan Zietsch from the University of Queensland in Australia and his research team set out to discover why genes associated with same-sex sexual behavior (SSB) continue to flourish.

“Because SSB confers no immediately obvious direct reproductive or survival benefit and can divert mating effort away from reproductive opportunities, its widespread occurrence across the animal kingdom and human cultures raises questions for evolutionary biology,” the study authors wrote.

“If, in the evolutionary past, SSB has on average been associated with lower rates of reproduction, then in the absence of countervailing forces, genetic variants associated with SSB would be expected to reduce in frequency until the behavior disappeared from the population.”

What the researchers found was those genetic effects associated with SSB found in people who only participated in opposite-sex sexual behavior granted a reproductive advantage.

“We showed that, among individuals who had never had a same-sex partner, genetic effects associated with SSB are associated with having had more lifetime opposite-sex partners,” the researchers said. “Evolution usually favours genes and traits that increase reproduction; so given that individual differences in sexual behaviour towards one or the other sex are associated with genetic differences, why might genes associated with non-reproductive sexual behaviour have survived evolution?

“We tested the hypothesis that genes associated with SSB may, in opposite-sex sexual behaviour (OSB) individuals (i.e. individuals who had only opposite-sex partners), be advantageous, thereby offsetting the evolutionary cost of those genes,” the scientists said.

To determine the effects of genes linked to SSB, the research team interviewed and examined genetic data of hundreds of thousands of people in the U.S. and U.K.

“The fact that SSB exists across human and animal populations is thus often discussed as a Darwinian paradox,” the study states.

But Zietsch said the increase of opposite-sex partners with genes linked to SSB could explain why such genes continued to endure through human history.

“In our evolutionary past (before people started using effective contraception), men who had more lifetime sexual partners may have had a reproductive advantage and, on average, have had more children,” he said. “This could help explain why genetic variants predisposing to SSB have been passed down from generation to generation, despite individuals who engage in SSB having, on average, fewer children.”

The researchers urged caution about their findings however, as the samples of people were drawn exclusively from the U.S. and U.K. They said more research is needed with a broader population.  

Categories / Health, Science

Subscribe to Closing Arguments

Sign up for new weekly newsletter Closing Arguments to get the latest about ongoing trials, major litigation and hot cases and rulings in courthouses around the U.S. and the world.

Loading...