>you're assuming every trait in a
>species must contribute to reproductive success, or it "declines"
>in frequency. This is a gross oversimplification of the theory
>of evolution.)
Wrong, I'm not assuming every trait must benefit reproductive fitness, they very well could be neutral to it, I am assuming that a trait that has a net NEGATIVE EFFECT on reproductive fitness should fade out of the population over time.
>Understood in this way, there is no puzzle about why exclusive
>homosexuality exists, regardless of reproductive effects: it's not a
>product of natural selection!
But it's quite unlikely that exclusive homosexuality is entirely the result of social pressure. Inheritance studies and twin studies indicate that the population that is remaining exclusively homosexual is genetically influenced. Even if we assume this genetic predisposition somehow spontaneously emerged in the last few hundred years, there is the question of why the trait isn't declining and instead remaining at a steady rate in the population. A net negative effect on reproduction should lead to a decrease in the propagation of the genetic predisposition. This isn't happening, hence the puzzle biologists are legitimately curious about.
>What has "emerged out of the blue" is the social demand for people to
>be exclusively homosexual or heterosexual in their sexual behavior. The
>stability of these sexual categories over the past few hundred years
>(not the last 10,000!) is a product of social relations.
Why assume this? Where is the overwhelming evidence that this is what's going on?
Let's try to remember how this facet of the discussion started, you challenged Boddi's statement about homosexuality being a puzzle for evolution which led to a series of exchanges where I took pains to explain the rationale this puzzle is premised on, the same one that has led evolutionary biologists to investigate this matter. But since you are so utterly convinced that their endeavor is entirely wrongheaded, I urge you write to them with your contravening evidence so they can be set straight and are able to put their research and resources to better pursuits.
Arash