The country is moving rapidly from cringing at gays, and gay marriage, to acceptance of any loving couple relationship as equally legitimate before the law, in terms of rights and responsibilities. This post is triggered by the remarkably rapid turn of events by which even some Republicans are emerging from what seem like cretinous shells to accept, if not avow, the acceptability of gay coupling in our society.
The issue is not new, nor specific to our time and culture. These things are always based on cultural judgments. Homosexuality is related to mating, which is related to deep emotional issues of many kinds. Mating-related issues include sex itself, procreation, resource acquisition and protection, group coherence and alliance, and so on. But biologists favoring the relaxed laws are now quoted in the op-eds as lending Darwinian support to the argument, by claiming that because homosexual activity is widespread in nature, we should legalize it. Of course, the do has nothing to do with the should. The latter are cultural.
Unlike other species, religion is also part of any culture's coherence and solidarity, as well as resource control mechanisms. In our culture we allow many religions, and they differ on almost any issue one can name. Sex and marriage are among them. In our society, religion cannot prevent homosexual feelings, but if one's religion prohibits gay activities or gay unions, then a believer must follow those tenets. (Actually, other species have social norms and these can be locally variable. Some may in some ways react to, or even try to suppress, homosexual activity)
Homosexuality is part of the naturally occurring variation in humans, and many if not most other species. Because of its potential effects on our material interests of the above sort, and because humans are tribal and proud of it, society may care strongly and emotionally about it. Policy may change this way or that over time. That's because these are cultural responses. They have nothing to do with the biology itself, and culture cannot dictate what is 'natural' (no matter that it may claim to do so).
Biologists have no business (as biologists) chiming in here, no matter that we see their papers and op-eds noting how widespread homosexuality is (and, presumably, therefore we should remove legal restrictions). Comparative biology is absolutely irrelevant to the issues, and biologists provide zero relevant knowledge in this regard. The issues are the same whether sexual preferences were hard-wired in our genomes or as totally free-willed and non-genetic as what brand of potato chips one chooses to eat.
So we are moving towards an acceptance, even as unremarkable, of gay unions, and most of us think that's a good thing because it allows personal freedom when that freedom doesn't interfere with others' freedom.
There is no seriously new kind of precedent here. Multiple sex partners, 'fornication', divorce, menages a trois, not to mention miscegenation, and so on have also histories of prohibition and acceptance. And, of course, so do very delicate issues like the age of sexual consent, for which there is certainly widespread cultural variation and definition around the world.
Most educated people are aware of this cultural arbitrariness, but many tea heads may be so rooted in their fears and the here-and-now that they're not.
One of the arbitrary aspects of sexual behavior is polygamy. This issue has been put back on the table in recent years, often by reactionaries objecting to gay rights. We're not expert on religion, but certainly the sacred texts of Muslims and Mormons allow, if not encourage, polygamy.
Polygamy is common in cultures around the world, both contemporary and indigenous. There are rules based on kinship, religion, group identity, social status and the like that, in any given polygamous culture, regulate it, as cultures regulate other forms of sexual union.
We're not here advocating such a change, nor opposing it, but just commenting upon it from a scientific (anthropological as well as biological) point of view. It is worth thinking about, because it challenges the degree to which most people seem to believe there are ultimate rights and wrongs--even though we know these can change, as the move towards accepting gay marriage shows.
Is legalizing polygamy going to be on the front burner in the near future? There are absolutely no objective reasons why we should prohibit polygamous unions any more than we do gay ones. In both cases, as in normal heterosexual marriages, we have protections against abuse, limits on resource hoarding, rules about the care and education of children, and so on.
How far to go?
If we are scientists, we should also consider how far one should go in this kind of reasoning. Is there any objective guideline for these sorts of thing? Suppose it to be true, as so often joked about, that sex with animals, as in the proverbial shepherd-sheep escapades, is also part of the normal spectrum of human sexual behavior. Should this bestiality be something to which the law is to be distanced in the name of freedom? We would not need to deal with 'marriage' here, since that can objectively be defined as involving humans since it's about human rights, property and the like--but then, why can we leave property to dogs in our wills?
We're just musing here, but it is important to think about where our ideas and sense of meaning comes from, especially when the discussion can be made, or forced, to hinge upon claims about what is 'natural'. There is nothing wrong with drawing lines around what is acceptable, but we should realize the culture-specific and in that sense highly arbitrary nature of those lines.