I've been contemplating on marriage and biology. I'm currently in the middle of reading Richard Dawkins' The Ancestor's Tale
. In it he mentions something I'd known but then forgotten: species that display sexual dimorphism tend to not be monogamous. To put that another way, if the males of a species are larger than the females, the males tend to mate with more than one female. The flip side of this is that many males in these species don't mate at all. A couple of examples are Elephant seals and Elk. In both the males fight to maintain harems of females to which they hope to be the only males available for mating. Horses don't display such dimorphism but do have the same style of mating in the wild; so there are exceptions. Now lets turn our attention to humans. There is probably no one who would dispute the idea that men are larger and stronger than women. This would seem to indicate that at some point in our evolutionary history, humans mated in a strong-male-maintains-a-harem kind of way. And there are plenty of cultures around the world that practice polygamy. The idea that God (or as I like to call him, My Imaginary Friend) handed down the Rule that marriage is one man and one woman is not supported by the facts on the ground. So our friends in the more 'fundamentalist' branch of society, in their attempts to protect their version of marriage from the ravages of our homosexual friends, are just defending their own aberrant form of marriage from a slightly different aberration. One man and one man or one woman and one woman are much closer to one man and one woman than one man and multiple women. But one man and multiple women is much closer to our evolutionary roots than any of the others.
I know that trying to reason with the nutjobs by appealing to science is a lost cause, but it is a fun argument to make.
And no, I'm not calling for polygamy. I'm just pointing out that marriage is a cultural construct that in our society has managed to somewhat disconnect itself from our biological heritage.