Although some people believe homosexuality be a strictly human thing, it has actually been known for quite some time homosexuality exists in a wide array of species other than our own, but two important questions still remain: what exactly is the purpose of homosexual behaviors and why could they have evolved? Note that, in the case of non-human animals, homosexuality refers only to observed behaviors, not the sexuality of a particular animal; since non-human animals cannot directly report on their sexual preference.
One proposed explanation is that these behaviors are an imitation of heterosexuality or are simply heterosexual behaviors performed in a dysfunctional manner. This version of explaining away homosexuality often takes on several forms that are very similar to ways in which human homosexuality is often approached by prejudiced, close-minded individuals. One of such forms would be that animals participating in homosexual interactions take on either the “male” or “female” role in all sexual interactions, as if such interactions couldn’t occur any other way. What this sort of explanation does is state that heterosexual interactions are the default and if any other sort of sexual interactions should occur, they will be modeled based on the default. In humans, this sort of thinking is often employed with questions such as “So, who’s the man and who’s the woman?” or “Who’s more masculine and who’s more feminine?”
In reality, there have been numerous observations of both males and females playing both the “male” and “female” roles in sexual interactions. An excellent example of this can be found in Marion Hall’s 1983 study of Red Deer, which details males and females of the species acting as the “male” and “female” in both heterosexual and homosexual interactions, with males sometimes taking on the “female” role of mountee and females taking on the “male” role of mounter during copulation.
Another proposed explanation for homosexual behavior is that it is only present if not enough of the opposite sex is present, leaving the animals in such populations so sex deprived that they will mate with any nearby member of their species regardless of sex. This has been directly refuted by a number of studies, of particular interest being Paul Vasey’s 1996 and 1998 studies on Japanese Macaques. His studies demonstrate how females often engage in female homosexual partnerships or “consortships” regardless of the number or aggressiveness of males present within the populations studied. Not surprisingly, a similar argument is often made for the higher rates of human homosexual behavior within sex-segregated populations such as bordering schools.
It has also been proposed that homosexual behaviors in animals are just products of sex mis-identification, meaning that animals mistakenly engage in sexual interactions with others of the same sex because they couldn’t tell the difference between the sexes of their own species. As ridiculous as that may sound, it is a common tactic used by many prejudiced scientists in the field of animal behavior to avoid addressing homosexual behaviors for what they are, even more so than the other explanations previously discussed. Once again, this has been disproved by several studies. Hall’s study mentioned earlier demonstrates how homosexual interactions are fairly common in a species in which the sexes are very distinguishable; however that is not the only example, homosexual behaviors have been reported in dozens of species from Giraffes to Ostriches to Woodpeckers, all of which are sexually dimorphic to some degree.
Furthermore, there are many species that have virtually identical sexes in which homosexual behavior has yet to been observed in. In addition, if mistaken identity was truly the case, then why have long-term, same-sex breeding partnerships and/or longtime companions been found in many species, such as the Black Crowned Night Heron? With such a large number of questions with and deficiencies in these popular “explanations” of homosexual behaviors in animals, it becomes quite clear that much time has been spent in avoiding the topic at hand instead of actually investigating it honestly.
Lastly, even outside of homosexual interactions, a plethora of other sexual behaviors exist that provide support for the notion that some animals could have a continuum of behaviors and/or gender expressions comparable to that of the human sphere of sexuality. One category of such behaviors would be non-conceptive behaviors; in other words, behaviors carried out in heterosexual interactions that do not result in reproduction through penetrative intercourse. Examples of these behaviors include: manual genital stimulation, oral genital stimulation, and non-penetrative mounting behaviors. The other major category of behaviors would solitary masturbatory ones, which have been observed to occur in a variety of situations, from purely self-stimulation due to limited mating opportunities or to “prepare” themselves for sexual encounters.
So, all in all, there has been shown to be an enormous amount of collected observations demonstrating a wide range of diverse regarding the sexual behaviors of most “higher” animals such as mammals and birds. Comparatively, there has been little concrete evidence or unanimous agreed upon support for any particular explanation, evolutionarily or otherwise, of said behaviors. When presented with this situation, it seems it would be best to accept that, possibly, the animal kingdom contains just as much variation in sexuality, gender expression, etc. that humanity does, albeit in different, less obvious way.