How do you go about determining the mental states of animals? Moreover, as was said way upthread, homosexuality may be as adaptive in humans as in other animals.The reason I say that is because after reading that article, it's pretty clear that animals engage in homosexual behavior for WAY different reasons than we do. They either don't understand what they're doing, or they do it for reasons that actually help their pack/flock/pod/whatever.
There's no reason to assume that some animals don't prefer homosexual or hetrosexual sex. The fact that some humans are exclusive in this regard may have more to do with culture than biology.Humans on the other hand have the mental capacity to make a choice. We prefer one over the other, and some do prefer both.