My last post, The Gay Brain, really got some of you talking. The central thesis of the video was that even though scientists have yet to identify the "gay gene," the vast consensus in the scientific community is that homosexuality has a strong genetic basis, based on multiple studies that point to heritability of LGBT identification and behavior. Many scientists believe that there is not just one gay gene, but in fact a multitude of genetic markers that are either switched on or off by a complex dance of epigenetic and environmental factors. Either way, it cannot be denied that being gay is rooted in one's biology.
At the end of the post, I asked what all of this means from an evolutionary perspective. Chosenfew79 left a comment that summarizes the questions that were raised by many of you:
If we look at this question from the perspective of modern humans, it appears to be somewhat short-sighted, since we all know that gay men and lesbian women can produce offspring just like heterosexual men and women can. They have all of the requisite anatomy, capability, and even the drive to have children, they just don't engage in the behavior necessary to procreate. In addition, from a modern perspective, we know that homosexuality is not a behavior per se, it is an identity, a point that was raised, sensitively and beautifully, by many commenters throughout this discussion.
But from the perspective of simple scientific curiosity, I think that chosenfew79 raises an extremely valid query. Natural selection posits that genes which increase reproductive success (those with higher fitness) will be selected for by the changing environment, and those with lower fitness will be selected against, ultimately washing them out completely, or at least keeping their numbers significantly low in a population. Neutral mutations (those that neither increase nor decrease an organism's reproductive success) will remain in relatively constant numbers throughout the population. From a modern perspective, I am very cautious to apply Darwinian natural selection to the human population, since we have decommissioned evolution in so many ways (medicine, technology, etc.). I personally believe that we have become a species of artificial selection pressures. But, from a historical perspective, it is an interesting exercise to look at how genetic contributions of homosexuality may have been preserved and passed down by our ancestors.
Nobody knows evolution better than Dr. Richard Dawkins, and his take on the evolution of the "gay gene" is fascinating, elegant, and quite clever. Bear in mind, the language used in this interview may not be safe for work.
What do you think?
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