Charles Darwin

One of the great questions about homosexuality in humans and animals is the question of how it serves procreation and survival. Most specifically, why do animals engage in non-reproductive sexual behaviors? 

Researchers Nathan Bailey and Marlene Zuk provide a variety of answers in their paper Same-Sex Sexual Behavior and Evolution (pdf). It offers a wonderfully brief (7 pages of text) but highly informative academic perspective on the subject. They include a varied list of examples of how same-sex sexuality benefits various species, with some really fascinating examples.

Also included in this paper are useful suggestions for standardizing nomenclature for same-sex sexuality in animals. I don’t follow their structure, but then, I’m not aiming for the kind of linguistic precision scientific papers require.