Female seed beetles, one of which is attempting to mount another. Ivain Martinossi-Allibert

In a major kick in the balls to all the bigots and homophobes out there, new scientific research has provided evidence that homosexual behavior may actually be controlled by certain genetic traits that bring substantial benefits to the reproductive success of entire species.

Same-sex sexual behavior (SSB) has been observed in a huge number of animals, ranging from dolphins to lions, although the purpose of this type of conduct has been the source of great confusion for quite some time. After all, on the face of it, homosexual activity should have a negative effect on reproduction and survival rates.

Traditionally, scientists have tended to explain this behavior away as “perception error,” whereby confused animals somehow mistake members of their own sex for potential mates. An alternative theory states that SSB occurs as a by-product of a strong libido. Clearly, the development of a healthy sexual appetite is ideal for species survival, so this hypothesis essentially centers on the idea that an overflow of lust causes some animals to mate with members of their own sex, suggesting that the costs associated with this behavior are outweighed by the benefits generated by this strong sex drive.

However, more recently, researchers have begun to seek the underlying genetic basis of SSB, with some suggesting that the genes that cause these tendencies in one sex may simultaneously increase the reproductive prowess of the opposite sex of the same species.

The phenomenon whereby one gene influences multiple seemingly unrelated traits is known as pleiotropy, and an increasing body of evidence now points to the fact that this mechanism may somehow cause SSB.

To test this, a team of researchers from Uppsala University in Sweden conducted an experiment using seed beetles, which have been observed engaging in SSB. According to their study, which appears in the journal BMC Evolutionary Biology, some males have even been found with “entangled genitals,” presumed to be a result of same-sex copulation attempts.

Two female labradors. Simon Speed via Wikimedia Commons

The team selected those beetles that displayed the highest tendency for SSB in order to breed a line of gay insects that have a much greater propensity for same-sex mounting than the average beetle.

Interestingly, the researchers found that although the males of this line tended to readily engage in homosexual acts and therefore had reduced reproductive success, their female siblings were actually more fertile than those from other lines, laying more eggs and producing more offspring.

Based on this evidence, the study authors suggest homosexual activity among seed beetles is the result of “widespread pleiotropy,” concluding that “SSB in one sex can occur due to the expression of genes that carry benefits in the other sex."

Study co-author David Berger told IFLScience that while this observation suggests a “genetic mechanism” behind SSB in general, he “would be cautious about extrapolating these results to apply to other animals,” such as humans. In other words, the study does not suggest the genes associated with homosexual tendencies in people are connected to fertility rates in members of the opposite sex. However, the crucial take-home message of this research is that, given that pleiotropy is universal to all organisms, “there’s no reason why a genetic mechanism” of this sort can’t exist in humans too.

All in all, a read through the study should be more than enough to silence those who like to talk about homosexual behavior as “unnatural.” Unfortunately, though, the people that tend to make those sorts of remarks aren’t exactly famous for reading academic journals.


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