Written as an answer to “Heterosexuality pretty much ensures continuity of the species, homosexuality doesn’t. What’s the benefit of homosexuality?” on Quora.
You’re missing the point about evolution – it doesn’t select what’s best, but any trait that helps survival is encouraged because the “carriers” survive to pass on that trait. Thus, we end up as a pretty social, pretty cooperative, pretty “good” overall species, because the behaviours that we call “good” are those that we are genetically pre-disposed toward.
However, there are a host of traits that are evolutionary baggage – they either don’t contribute to survival (and also don’t detract from survival), or they are counter survival but they come into the genome as part of a package deal with a survival oriented adaptation.
I have no firm answers on where, evolutionarily speaking, homosexuality fits in. However, here are a few thoughts:
- in a family with one or more homosexual children, their existence (if they don’t become breeders from cultural pressure) gives the family one more provider without adding to the consumer count in any fashion. In a scarce resources situation, this may be more beneficial than simply generating more mouths that can’t be fed.
- a homosexual or bisexual male will not need to be as competitive about finding a mate as heterosexual males will be, for sexual release, so they are more likely to avoid fatal competitive situations, waiting until there is a less fraught situation in which they can select a mate.
- attraction can be a significant factor in creating relationships. Males who find other men attractive may be better able to form relationships and keep larger groups together.