And almost all, if not all, reference Bagemihl's ridiculous book. Its pathetic. Its a dumb argument for a dumb argument because why are you basing your behavior on an animal anyway?
The entire point is that a great many species including humans engage in homosexuality. It is not an uncommon occurrence today or throughout history. Not a mental illness as he says.
If you're going to rubber stamp any human behavior as 'normal' because some animals may do it, that's just fuckin insanity on your part. Animals shit in public - do you?
You're actually doing a pretty good job of proving your own mental illness, when you claim to use animal behavior as a litmus test for what is acceptable human behavior.
So its not a mental illness for people to do something as long as animals do it? You're an idiot. My dog eats cat shit - is that ok for people to do at your house?
There are people who eat shit, and like it. Coprophilia. Which is not currently considered a mental illness unless the person eating shit is obsessed or distressed about it.