The unrestrained, animal instinct would, presumably, lead to a whole lot of indiscriminate fucking (and probably not a small amount of rape). I imagine this to be the default state of the uncivilized, uneducated human specimen.
The emergence of a belief in sexual purity as a moral virtue, as pushed by a number of popular religions, seems poised to contain and control human sexuality. The natural sexual appetite is reconceptualized as the sin of lust, which must be tamed and expressed only in particular, controlled situations (approved by the church, or government), else one succumbs to moral corruption.
It would be naive to think that this strategy has been employed throughout the ages for strictly altruistic purposes; but, at its best, it seems intended to be a civilizing influence. However, it is a very blunt tool applied to the very subtle subject of human sexual interaction.
In the middle ages, this simplistic, black-and-white approach may have been adequate. But I would argue that we have evolved to the next level. Certainly, in the 21st century, amidst all the clamoring for newfound sexual liberation and tolerance, it would seem as though we were ready for a more nuanced understanding of human sexuality.
Hedonistic sexual anarchy is one end of the spectrum. Holy virginity is the other. Have we not reached a level of cultural sophistication where we can distinguish positive and destructive sexual acts through their impacts on the individual people involved, rather than making broad proscriptions on certain kinds of contact?
Are we not at a point where we can understand that the human sexual appetite is not sinful, but natural, and that there are merely healthy and unhealthy ways of expressing and indulging in it? Do we not live in a modern society that believes in fundamental liberty and the civic rights of the individual?
Need we continue to be corralled by ordained shepherds who preach lowest-common-denominator approaches to sexual ethics, that limit the freedoms of the sophisticated individual for the sake of the simple-minded fool? Is it not time to refocus our attention on the rules of ethics in lieu of superstitious morality?
I'm ready. I don't know about you.