I wondered the same question, it sounds palausable for homosexuality to be a sort of saftey valve for the race.

But in looking to it,,,

first off evolutionary growth is always about indivual ability to reporoduce nto group or species*, evolution works mainly by each individual trying to spread their genes as much as possible and a trait that stopped spreadig of genes just wouldn't logically develop by this method

* I asked my bio proffessors what about bees and monkeys that help eachother out and stuff and he said they don't violate this and showed proofs that I found to be shady and I dunno *shrug.

also how do individaul bodies (not minds but hormones glands) "know" over=population is happening? Gay people in America for example aren't seeing hunger or lack of ejaculation (which the body will see as chance to spread genes) that might "indicate" it the way weather indicates season to animals and stuff,,,so gay people in developed countries are a kinda counter example...

also homosexuality's leading theory as to why it exists ("exotic to erotic" kinda interesting you can google it..) is mainly psychologicaly based not "genetic" ,,,but then genetics <> psychology is a murky issue

also gays were around well before population..,The Greek Empire is one of the gayest things to ever happen and Benjamin Franklin (again no enviromental factors indicating overpopulation..opposite) was freeekaaayy.


so yeah,,interesting question,,,above is what people told me in school about it,,,

I would say technolgoy will be the thing that does humans in....so does this which I found interesting.. http://www.rotten.com/library/medicine/superbugs/