A new study led by scientists at the University of Michigan (United States) has found genetic variants associated with human bisexuality related to a greater likelihood of engaging in risky behavior. Evolutionary biologists have long wondered how the genes associated with this behavior have been maintained in the human genome and whether they will persist in the future, since, as we all know, having sexual relations with someone of the same sex is not useful from the beginning. evolutionary point of view because it does not allow having descendants.
The researchers analyzed data from 452,557 individuals of European ancestry registered in the UK Biobank genetic and health information database. Participants responded to a questionnaire that included the question: “Would you describe yourself as a risk taker?”
They found that heterosexual men who carry the genetic variants associated with bisexual behavior, known as BSB-associated alleles, father more children than average, and that men who acknowledge taking risks tend to have more children and are more likely to have to carry alleles associated with BSB. The findings have been published in Science Advances and suggest that male BSB-associated alleles provide reproductive benefits due to shared genetic variants between male bisexual and risky behaviors.
A risky behavior that increases the probability of having children
“Our results suggest that male alleles associated with BSB are likely to be reproductively advantageous, which may explain their past persistence and predict their future maintenance,” said University of Michigan evolutionary biologist Jianzhi Zhang, lead author of the study.
“These results also suggest that risk behavior is the underlying cause of the promotion of reproduction by BSB-associated alleles in heterosexuals. That is, the reproductive advantage of BSB-associated alleles is a byproduct of the reproductive advantage of risky behavior,” said Zhang, who is the Marshall W. Nirenberg Collegiate Professor in the Department of Ecology and Evolutionary Biology.
Self-reported risk taking is likely to include unprotected sex and promiscuity, which could result in more children
Risk-taking propensity usually describes a tendency to take actions with the goal of obtaining rewards despite the possibility of suffering negative consequences. Although the UK Biobank question on risk taking did not specify the type of risk, self-reported risk taking is likely to include unprotected sex and promiscuity, which could result in more children, Zhang said. .
In their analysis of the genetic underpinnings of same-sex sexual behavior, the researchers looked at both bisexual behavior and exclusive same-sex behavior, which they call eSSB. When they compared the genetic basis of bisexual behavior with the genetic basis of eSSB, they found that they were significantly different. They found that genetic variants associated with eSSB are correlated with fewer children, which is expected to lead to a gradual decrease in their frequency over time.
The researchers have highlighted, however, that their study analyzes the genetic foundations of sexual behavior between people of the same sex and not the behaviors themselves, which are influenced by both genetic and environmental factors. Indeed, the proportion of UK Biobank participants reporting same-sex sexual behavior has increased in recent decades, which they attribute to increasing social openness.
Furthermore, the authors of the study have emphasized that their results “contribute predominantly to diversity, richness and a better understanding of human sexuality. “They are in no way intended to suggest or endorse discrimination based on sexual behavior.”
