REQUEST: In this post I do not refer to, nor do I encourage reference to, any ethical/moral/emotional aspects of homosexuality. So please don't start an pro/anti- LGBT campaign in the comments section.
Are mammals (other than humans) known to engage in homosexual activity of any sort?
From the way I see it, homosexual activities carry no evolutionary or reproductive benefit: No offspring produced, no continuation of species...hence pointless.
Yes, I get that the "need to mate and to produce and protect offspring" is hard-wired into every (normal) mammalian brain. If I've interpreted this correctly; intercourse is a fairly energy-expensive act so if there were no immediately clear "incentive" for mammals to mate they wouldn't mate at all, hence heralding the decline and eventual extinction of a species. Nature solved this conundrum by ensuring that the brain would perceive intercourse as highly pleasurable, thereby securing the necessary "incentive" for mammals to mate.
The only "flaw" here, is that simply stimulating the genitals is sufficient enough to elicit a sensation of pleasure. So there's no real need to go through all the trouble of finding a suitable animal of the opposite sex and "do it" to feel good. A sufficiently intelligent mammal would soon figure that out; so this opens up two more possibilities: 1) Masturbation and 2) Homosexuality. (Since this post's on Homosexuality, I'm only going to deal with the latter)
So, a mammal intelligent enough to figure this out would have three options before it : 1) Heterosexual activity, 2) Masturbation, 3) Homosexual activity; the last two options being a way to bypass Nature's original intent.
So before I continue, I want to make what I mean by "homosexuality" very clear:
a) A being that displays option 1) or both 1) and 2) is heterosexual.
b) A being that displays options 1) and 3) [and maybe 2) too] is bisexual.
c) A being that displays option 3) or both 3) and 2) is homosexual.
[Just to make it explicitly clear, a homosexual will always steer clear of option 1)]
So let me just put all of that together and re-phrase my question:
Q- Are there any known instances where a (non-human) mammal consciously avoids heterosexual acts and instead prefers to engage in homosexual activity
Personally, I find this doubtful, since the existence of homosexuality (among humans) is the unintended result of Human self-consciousness/intelligence, something that other mammals apparently lack.
HOWEVER: (Considering another possible reason for homosexuality)
If occurrence of homosexual tendencies is (also) due to, say, the stochastic, faulty "hard-wiring" of the human brain due to mutation or damage to neural tissue (I'm not sure if this really is one of the reasons for homosexuality), then it would seem plausible that other mammals could also be affected by this stochastic "fault" and thereby display homosexual tendencies.