An article in The Washington Post presents a new approach to same-sex relationships in animals (and humans, by implication). Researchers argue that heterosexuality is a pretty recent invention, as far as evolution is concerned.
When Procreation is a God
Traditionally homosexual or bisexual practices have been seen as deviations that need to be explained. The premise is that sex is for pro-creation, so same-sex sex makes no sense. Why does not evolution eradicate such behavior, given that it does not lead to offspring?
Ray Blanchard, the man behind the transphobic autogynephilia theory is, for instance, deeply anchored in this way of thinking. He has spent a lot of time trying to explain why homosexuals exists. Moreover, he presents both homosexuality and transgender conditions as mental illnesses, again because they – presumably – do not lead to procreation.
(Why “evolutionary psychologists” have decided to make procreation God and the ruler over right and wrong will have to be addressed at another time. It makes little sense to me.)
Same-sex behavior is the starting point
The report presented in the Washington Post takes a completely different approach. Polysexuality might just as well be the natural default, if I understand the researchers correctly. Same-sex behavior has always been there.