Homo Re: Thanks, Science! Now, About That Parade…
OK, I first want to say, I am not an evolutionary biologist. And group selection is not universally repudiated by evolutionary biologists. But I do think that this urge to define homosexuality as a “good” gene is kind of messed up.
We are not our genes. There are a lot of hypothetically adaptive traits (murdering other people’s babies, say) which, if they existed, we would be right to resist, for reasons of morality, social harmony, etc. Imagine if there were a gene that decreed that some men have a violent desire to have sex with women, even if the woman doesn’t show signs of consent. That might very well be be an “adaptive” trait, in the narrow view of natural selection: the raped ladies would give birth to lots of kids with your genotype. (The phenomenal reproductive success of Genghis Khan, recently publicized by this fiasco, is a possible illustration of how this would work—mind, I’m not claiming that Genghis Khan had any specific genotype that expressed itself to that effect.) But those men would be right, in a moral sense, to resist their genetic “destiny.” All “adaptive” means is that a given phenotype is more likely meet with reproductive success in the next generation, thereby passing on its underlying genotype to a greater proportion of the population. It’s completely value-neutral. Conversely, there are a lot of hypothetically maladaptive traits—in the sense that genetic success would be decreased—which we might be inclined to celebrate, because they make our society better, or perhaps the very fact of not resisting them makes those individuals happier and more productive members of our society.
Homosexuality might very well be an example of a technically maladaptive trait. Luckily, there’s not just one or two genes for homosexuality—it’s probably a lot more complex than that. So there’s little chance that it would be bred out in a few generations of gays avoiding getting themselves into unhappy heterosexual marriages.
Now, perhaps I’ll be proved wrong, and group selection will be a convincing explanation for why homosexuality persists in spite of its strictly nonadaptive aspects. But I kind of think it’s a blurry convenient solution to a political annoyance, not a true scientific challenge to natural selection. (Or even sexual selection, which though it might be limited, almost definitely exists in bowerbirds and peacocks and so forth.)
Any real biologists want to weigh in?