Homosexual Behavior in Animals: Is Same-Sex Attraction Unique to Humans?

Japanese Macaques performing mounting (Image from BBC) 

Thankfully, attractions that falls outside of the long-standing heteronormative views of traditional society are becoming increasingly acceptable in today's modern world. However, there are still many who oppose such behavior, often denouncing it as aberrant and unnatural. Is it though? As it turns out, homosexual behavior amongst animals other than humans doesn't just exist, it's common in many species of birds, mammals, and even oh-so-inhuman insects.

For many, homosexual behavior is an evolutionary paradox: why would any animal waste time and energy engaging in sexual behavior that will not yield offspring. Such a behavior's existence in modern creatures seems to be in violation of Darwin's theory of evolution; since such behavior has such a great cost in time and energy and yet doesn't improve a creature's fitness, surely it would have been selected against strongly enough to be all but non-existent today? However, new research shows that different species of animals practice same-sex sexual behaviors, or SSB, for a variety of reasons, from simply seeking pleasure to needing a partner with which to raise a child.

    

For some species, SSB has been linked to immaturity, such as in fruit flies. In the early minutes of these insects' lives, males will attempt to mate with whatever other members of their species they come across, until they begin to develop an awareness of which flies are available females, and go on to focus on mating with those individuals. Such an approach to mating might seem wasteful, but it provides a potential solution to the question of why SSB exists. Such indiscriminate mating is an effective way for young animals of a species to maximize their chances of producing offspring early on in their lives, as it reduces the possibility of missing valuable opportunities to reproduce. In fact, researchers published in the magazine Scientific American hypothesized that sexual behaviors almost certainly evolved before many of the traits species use today to distinguish members of the different sexes, and so same-sex sexual behavior likely predates many species' ability to identify and target their efforts on potential mates of the opposite sex.

Fruit flies mating (image from The Scientist Magazine)

  

For other animals, sexual behavior is a means of strengthening social ties, and as such is just as important between members of the same sex within a population as between those viable to produce offspring. As pointed out in an article by the BBC, some of our closest relatives on the evolutionary tree, bonobos, use sex for a variety of reasons including to ease tension between individuals who have fought recently or to climb the social ladder by engaging in sexual behavior with more senior members of the community. As animals that exist in tightly-knit social groups, such behavior doubtlessly provides a benefit, tightening social bonds and strengthens the community unit.

The so-called "bonobo handshake" (image from CBS News)

Despite the evidence posed by these examples and numerous others from across the animal kingdom, there remains currently only one species aside from humans so far has been found to contain members preferring same-sex life partners, and that is domestic sheep. Found to have slightly different brains to other sheep, these males will completely forgo mating in favor of remaining partnered for life to another male sheep. It is unclear if this behavior is the result somehow of sheep's domestication, or how the genes coding for these individuals unique brain development have managed to remain present in the gene pool since they cause what seems to be such a large drawback to the sheep's ability to reproduce. 

(image from Wikipedia)

While much remains unknown about the drivers behind homosexual behavior in animals, and questions remain as to if truly homosexual specimens can be found in wild animal populations, the information so far gathered is certainly interesting to explore, offering a divergence from the traditional heteronormative narrative of human history. Whether we realize it or not, our perceptions and knowledge of ourselves deeply influences how we perceive and approach our surroundings, and hopefully as society becomes more accepting of the differences that exist between all of us, our pursuit of science can become more open-minded and comprehensive as well, expanding into areas that were previously ignored or unknown as we continue searching to ever improve our understanding of this wonderful world and our place in it.