homo homo sapiens sapiens: evolving views of homosexuality October 5, 2010Posted by Danjamin S. Meow in : idols, relationships, religion , trackback
Same-sex mating seems at first to be detrimental to the furtherment of any species. When you think about it, two male zebra finches bunking down together seems like a pretty selfish act. I won’t go into where they get the bunk from, but they’re not going to procreate to further their own species. From a narrow view of natural selection, the “homosexual finch” gene seems pretty doomed. After all, only individuals carrying genes which promote their chances of a) survival, or b) reproduction survive to reproduce and pass on their set of genes. At first glance, homosexuality seems to fulfil neither of these requirements. Often though, nature works in ways that would’ve blown Darwin’s mind. Like finches getting down with each other just to prove to human scientists that homosexuality is not “unnatural.”
Darwinian trade-offs are common in nature: take, for example, the peacock’s tail. The prescence of a flamboyant, conspicuous tail might be an attractor for peahens (who exert sexual selection on males, “choosing” partners with genes coding for attractive tails, and thus producing male offspring with flamboyant tails). There’s something to be said for subtlety and camouflage when it comes to avoiding predators, though. The term “survival of the fittest” is something of a misnomer, since Darwinian fitness doesn’t necessarily mean most likely to survive and live to a ripe old age. Sometimes it means fit enough to survive to maturity and reproduce and that’s it.
So how does this explain the fitness of homosexuality? Back up a minute, buster, you’re jumping the gun a bit. Firstly, the gene(s) coding for homosexuality are not 100% penetrative or deterministic. In 56 sets of identical twins within which one member was gay, approximately half of the other twins were gay also (Adler, 1992). This suggests a strong but not determinative genetic component, or that the set of genes you carry in your jeans do not tell the whole story of your sexuality. (Before you claim that in half of those households there may have been an overbearing mother and an absent father consider that of three cases of identical twins separated from their gay twin at birth, the other twin was homosexual in two cases (Bouchard, 1990). Scientists studying heredity and the genetic components of phenotypes like homosexuality often study sets of identical twins adopted out or otherwise raised in different households, never seeing their twin during childhood and thus allowing for differing environments in the expression of their genes.)
Richard Dawkins calls one aspect of the non-penetrative characteristic the sneaky fucker theory – a bisexual individual or one whose primary attraction is to the same sex can still mate with members of the opposite sex. The probability that the offspring of such a mating have any one of the same-sex attracted parent’s genes is 50% for each of those “gay” genes; genes which may be beneficial for other reasons. For example, the allele coding for sickle-cell anaemia causes abnormal, rigid, sickle shaped red blood cells. The shape and lack of flexibility results in a greater risk of various complications but also offers a trade-off in offering greater protection from malaria in those carrying one copy of the gene. Not to suggest that homosexuality is a disease, but the resultant decrease in the likelihood of reproduction can have other benefits.
Early humans (and many of our primate cousins) lived in tribes or communities of related individuals, and we’re not alone in this respect. Lions, for example, are unusually social for members of the feline family. Solitary animals have to hunt, gather, find shelter and protect themselves from prey all by themselves. Humans and other species exhibiting altruism share food and shelter and protect each other because it expends less energy in doing so, and is thus a more efficient way of ensuring your genes survive. Having your own offspring is only one way of ensuring your genes survive. Non-breeders are also helping to spread their genes by contributing to the survival of their family (you share half of your genes with your siblings, after all). Not having children of your own means that you have more time to spend doting on your siblings, nieces and nephews, which increases their Darwinian fitness and long-term chances of survival.
Moving from early humans to the greater social communities modern humanity has created – cities, nations and continental unions – brings our world view up to date to focus sharply on a planet containing finite resources and populated with seven billion people. Under these circumstances, creating an understanding of our diverse differences seems necessary to foster tolerance and accept each other to aid the survival of our own species as well as those we share the planet with. Capitalism encourages population growth because it increases revenue by increasing the number of workers, creates jobs in the expansion of infrastructure and places more demand on the resources sectore. But since sharing resources, like land or raw materials, and preservation of biological diversity by protecting endangered species from the expansion of humanity are things that we haven’t really done so well in the past any trait decreasing our rapid proliferation should probably be encouraged, rather than ridiculed, discriminated against, and singled out for punishment.