[sevenless]

The basic flaw in this is that there's no straightforward heritability for homosexuality, so regardless of the evolutionary pressures, it's not something that could be obviously 'selected against'.

Homosexual men throughout history did reproduce, though. In many ancient societies, norms were such that you had kids (if you survived long enough), and what you did with other men on the side was more or less your business. The Romans had a lot of gay sex, but didn't have a concept of a gay man, rather an effeminate man (who liked to bottom). So homosexuality is not really a puzzle that begs for a solution. The reality is, that the reasons we have sex do not have much to do with reproduction. Western society is still rather prudish about acknowledging this.

It's worth pointing out also, men generally pass their genes on a whole lot less than women do. Genetic evidence shows women were twice as likely as men to reproduce. So it's not like being heterosexual meant you'd have kids, being homosexual meant you wouldn't. I guess monogamy would reduce the disparity between men and women here.

http://www.eurekalert.org/pub_releases/2004-09/uoa-ges091604...