Originally Posted by Xurtio

To expand on my first post itt, which was terse, there are members of species (especially in a supersocial species like humans) whose contribution is not to reproduce, but who contribute to the health of the population in varying ways. Now, you can't really talk in too much detail about evolved traits in this context because there's not much molecular evidence (the evolution of the kidney is easily traced compared to the evolution of behavior; this is a huge flaw of evolutionary psychology).

BUT, some ideas are the "gay uncle theory" and "kinship selection" (as a mechanism for "biological altruism"). Unfortunately, a lot of the research is cotroversial and political, so I try to avoid it. I don't need physical evidence of evolutionary relevance to treat people with different sexual orientation as equals, anyway.