posted
The only way to determine exclusive homosexuality would be long term observation, I think.
This article refers to male flamingoes who build nests together and even raise foster chicks (like the Penguins, who were only discovered to male/male partners after blood tests, but refused to mate with available females):
First article googled. It also says naturalists have been avoiding direct studies of homosexual behavior to avoid their work becoming political. It is probably worth noting that folks might get really upset if public funds were used to study this aspect of animal behavior, especially if it the results were not to their liking.
I would guess that the actual percentages of exclusively homosexual animals would be quite small, with more being bi and most being hetero.
quote: Many domestic and wild animals engage in sexual activity with members of both the same and the opposite sex; a smaller number have eyes only for their own sex. Some of these homosexual activities appear to boost reproduction. Female cows often mount each other, thereby signaling any bulls in sight that they are ready to reproduce. In other cases, same-sex affairs may help reproduction indirectly, by promoting the general fitness of a group or individual. For example, in some species, animals are more willing to share food with a member of their own sex after sexual activity with him or her.
Indeed, researchers interested in animal behavior and sexual selection have long held that the main function of homosexual endeavors is to ensure, in a roundabout way, that one's genes get passed along.
The sheep farmer who paid big bucks for a ram's mating abilities and finds the animal ignoring his ewes would certainly question this theory. Besides failing at their jobs, high-libido homosexual rams cause havoc in the sheep pens by disrupting other males mating with females.
For sheer ho-ho funny quote, I nominate:
quote:Sexual selection theory holds that animals pick partners that will increase their chances of passing on their genes, but this doesn't apply to homosexual macaques.
"I'm not saying Darwin was wrong, but there's room for working on the theory so it can accommodate observations of homosexual behavior," he asserts.
It's interesting, if intrinsically difficult to study.
quote: The discovery of estradiol differences in homosexual and heterosexual rams "complements recent reports regarding the genetic and anatomical correlates of homosexual orientation described in humans," Perkins and her colleagues proposed in the 1995 Hormones and Behavior.
However, Perkins and Fitzgerald "leave it up to each reader to determine whether mechanisms mediating sexual orientation in sheep could help explain similar mechanisms involved in humans." Perkins does note that humans and sheep have more similar reproductive systems than do humans and other laboratory animals, such as rats.
posted
There is absolutely no need to think that homosexuality has some kind of evolutionary function. Animals need some kind of mechanism for identifying possible mates; these mechanisms are clearly quite complicated at the cellular and chemical level, so there is every opportunity for the wires to get crossed. All that's required for this not to get bred out of the species is that the wire-crossing not be tied to any particular gene. Such subtle behavioral traits are generally emergent effects of many different parts of the genome. Finding a genome that did as well with heterosexual attraction without being susceptible to wire-crossing would probably require a large amount of mutations, with bad or even deadly effects in-between the two; in other words, we are currently at a local maximum of fitness, and the occasional homosexual who doesn't pass his genes on - too bad. (For that matter, many homosexuals do pass their genes on; it only takes one amting, after all.) Alternatively, homosexuality could be tied to a gene that does an important job, but is susceptible to causing same-sex attraction once in a while, perhaps under some particular set of pre-natal influences. Again, a local maximum.
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