As someone who finds human sexuality (and the causes behind it) fascinating, I was very interested to read this article on a recent genetic theory of male homosexuality. (Don’t worry, it’s much more readable than my description makes it sound.) The question it tries to answer is this: Assuming a genetic basis for homosexuality, specifically male homosexuality, one would think that it would be self-limiting – two men are incapable of creating a child to pass on their genes, after all. But male homosexuality is seen at a low-but-constant rate in all kinds of societies. So, what gives?
For those who are too lazy to even read Slate’s rundown, here’s the Campbell’s Condensed Soup version: The technical term is “sexually antagonistic selection”, which basically means that while the trait is harmful for one sex, it’s advantageous for the other – enough to make up for the deficiency introduced in the first sex. We’ve already seen examples of this odd occurrence in other creatures, so it’s more than plausible for it to happen in humans, too.
But Rose, I hear you thinking. In order for this theory to work, the male homosexuality gene needs to give females an evolutionary boost. What possible procreative advantage could women gain from having gay male relatives?
Glad you asked!
Here’s a fascinatingly odd bit of data: Numerous studies have found that the female relatives of gay men produce children at a significantly higher rate than other women. Not only that, but among the female relatives of a gay man, those who are related to his mother have even higher birth rates than those related to his father. So it’s quite possible that whatever gene is responsible for male homosexuality also causes increased fertility in female carriers – more than enough to offset the lack of offspring from their gay male relatives.
Assuming this theory is correct, that brings up a couple of interesting potential conclusions:
First, and perhaps most obviously, all the family-values folks who are so concerned about gay people spreading their gayness like a disease can bugger off (so to speak) – the lack of evidence for the gay-disease model is now supported by a strong argument that only men who are genetically wired to be attracted to other men will be. (The flip side of that, of course, is that male homosexuality will always be around at that low-but-constant level, so y’all just need to get used to the idea that some guys are just going to prefer other guys to women and that’s that. Leave ‘em alone, already.)
Secondly, this and several other studies attribute female homosexuality/bisexuality to societal rather than genetic factors, which could explain the increasing amount of evidence finding female sexuality to be far more fluid than male sexuality – we’re not genetically hard-wired the way most guys are, so most of us aren’t limited to being attracted to one sex or the other except by societal factors. (I don’t buy the oft-pronounced theory that bisexual males don’t exist; I’ve known several. They do seem, however, far less common than bisexual females. This would also account for the fact that when I ask friends about their thoughts on the all-humans-are-inherently-bisexual theory, female friends often seem more receptive than male friends.)
Thirdly, one could make a pretty strong argument that it’s not a male-homosexuality gene per se that’s getting passed along; it’s an androphilia gene, one that increases attraction to men. The above-mentioned accounts aside, I have met women who just couldn’t imagine sleeping with someone of the same sex. Usually they didn’t react to the idea with disgust, the way men did; they just (if you’ll pardon the vulgarity) really, really loved the cock. I’d be very interested in seeing the rates of homosexual males among their relatives as opposed to in the general population…
The one thing I’ll admit I’m worried about is that, as with all homosexuality-is-genetic theories, folk will start going on about how it just proves that them queers are inferior and have got faulty wirin’ and should be fixed (or worse, exterminated). I need to find a convenient link to the DSM-IV’s definition of a disorder – specifically, the part that says that in order for something to be a disorder, it has to cause mental or physical suffering to either the person exhibiting it or others interacting with them.
Further ponderance: that definition of a disorder applies societally when homosexuality is not accepted by the public or by the homosexual himself – creating cover marriages with one person or the various issues when you believe yourself to be inherently evil. (This is all theory since I am heterosexual and from a more permissive community etc). Therefore, it seems to classify as a disease *within the communities that persecute it a disease* and outside not so. Short of reliably eliminating homosexuality, the treatment of said disorder leads to be a societal treatment.
Nature seems to agree with conservatism on one thing though: namely that homosexuals need not procreate. Ironic, then, that conservatism provides pressure for homosexuals to have “normal” lives, marry, and have children. (This is not an argument on the right to procreate, but on the hardwiring that produces or does not produce offspring through sexual attraction, and the societal imperative to procreate regardless.) Do you have information on homosexual tendencies of male offpsring of closeted homosexuals?
Your first point is something I’ve considered myself on occasion. You’re probably aware that the DSM-III (and previous editions) defined homosexuality as a deviancy/mental disorder probably for exactly those reasons – it wasn’t seen as “normal”, and people (as a result) sought treatment for it. “Not a problem unless it causes you or others distress” is all well and good, but when said distress is caused by a baseless judgment on the part of society, is it the person or the society that needs fixing? (Also, wasn’t there a Star Trek episode about this very question?)
The study I was reading about didn’t give any information on the homosexual tendencies of the offspring of gay males, but I’m not sure how accurate such studies would be; a closeted gay man would be very strongly motivated to seek a woman who wasn’t really into sex. Amusingly enough, if the “androphilia gene” theory is true, that would mean he would most likely end up with a woman who wasn’t a carrier, and therefore any offspring they might have wouldn’t be any more susceptible than the general population. Potentially.
You’ve addressed an issue that often puzzled me: If homosexuality is genetic, then how come the gene responsible for it is passed to the next generation although two homosexuals cannot have children. Your explanation is that the same gene (or genes) which cause homosexuality in men also boost fertility in women, so the same gene offers an evolutionary advantage which preserves it. That is a pretty good explanation. I can’t think of a better one at the moment.
Thanks for posting this, I found it to be very interesting.
Certainly! Although really, you should be thanking William Saletan of Slate’s “Human Nature” column. I don’t agree with all his political views, but he does write some fascinating pieces on new discoveries in human biology and the social/ethical ramifications thereof.
I didn’t actually add much to his original article, but I wanted to rephrase the idea in my own words because it explained a lot of my experiences with male/female sexuality. Not all of them, for certain, but it might be one of the larger-scale influences.