Running out of time, so I am just going to post a few resources for those interested in biologists who research sexual variance in nature, and how non-procreative sex can be beneficial to a species, including humanity. This research challenges a number of assumptions about sexual selection that have been in place since Darwin wrote about them.
Cory blogged previously about my friend Joan Roughgarden, an evolutionary biologist at Stanford. Her book Evolution's Rainbow is an accessible overview.
I also recommend Bruce Bagemihl's Biological Exuberance, an extensive catalog of diverse sexual development and behavior. Their work challenges those who claim that non-procreative sexual behaviors are "maladaptive evolution" because they don't allow the individual to leave more offspring, but it's clear from many of our closest genetic relatives (especially bonobos) that sex is not just about reproduction. It is often about strengthening social bonds within groups, and that same-sex activity is an important part of that.
Joan has also been critical of Richard Dawkins' concept of the "The Selfish Gene
Evolution's Rainbow: Diversity, Gender, and Sexuality in Nature and People
The Genial Gene: Deconstructing Darwinian Selfishness
Biological Exuberance: Animal Homosexuality and Natural Diversity
