Over at Salon.com an historian Hanne Blank, author of a book called “Straight” discusses how we came to divide humanity into gay and straight. The Invention of the Heterosexual (Hint: Freud did it.)
(One thing I appreciate is that in the midst of a fairly standard narrative about how our generation invented love, sex and desire—gee, our generation is so great!—she at least acknowledges that marriage as a social idea was rooted in the need to manage procreation:
As you point out in the book, for much of human history, marriage had absolutely nothing to do with sexuality or sex.
It’s more that marriage didn’t have a lot to do with desire. Marriage has always had to do with sex, and the ability to have marital sex and preferably procreate has always been central to marriage. But what was not so important was whether or not you necessarily wanted to have sex with that person. It was your duty, it was paying the marriage debt, and you were gonna do it, by golly, but this was a co-worker, this a partner in business enterprise—not a person you chose to satisfy your own personal whims and desires with. If you happen to also like them and think that they were swell or pretty or handsome then that’s great. But that’s not what you were in it for.
And now everything has changed, because we now prioritize attraction, desire, love, romance, over the strictly economic and community-building aspects of marriage.