If you read any amount of history, you will discover that people of various times and places have matter-of-factly believed things that today we find incredible (in the original sense of “not credible”). I have found, however, that one of the most interesting questions one can ask is “What if it really was like that?”

That is, what if our ancestors weren’t entirely lying or fantasizing when they believed in…say…the existence of vampires? If you’re willing to ask this question with an open mind, you might discover that there is a rare genetic defect called “erythropoietic porphyrinuria” that can mimic some of the classical stigmata of vampirism. Victims’ gums may be drawn back on the teeth, making said teeth appear fanglike; they are likely to be photophobic, shunning bright light; and, being anemic, they may develop a craving for blood…

I think the book that taught me to ask “What if it really was like that?” systematically might have been Julian Jaynes’s The Origin of Consciousness in the Breakdown of the Bicameral Mind . Jaynes observed that Bronze Age literary sources take for granted the routine presence of god-voices in peoples’ heads. Instead of dismissing this as fantasy, he developed a theory that until around 1000BC it really was like that – humans had a bicameral consciousness in which one chamber or operating subsystem, programmed by culture, manifested to the other as the voice of God or some dominant authority figure (“my ka is the ka of the king”). Jaynes’s ideas were long dismissed as brilliant but speculative and untestable; however, some of his predictions are now being borne out by neuroimaging techniques not available when he was writing.

A recent coment on this blog pointed out that many cultures – including our own until around the time of the Industrial Revolution – constructed many of their customs around the belief that women are nigh-uncontrollably lustful creatures whose sexuality has to be restrained by strict social controls and even the amputation of the clitoris (still routine in large parts of the Islamic world). Of course today our reflex is to dismiss this as pure fantasy with no other function than keeping half the human species in perpetual subjection. But some years ago I found myself asking “What if it really was like that?”

Let’s be explicit about the underlying assumptions here and their consequences. It used to be believed (and still is over much of the planet) that a woman in her fertile period left alone with any remotely presentable man not a close relative would probably (as my commenter put it) be banging him like a barn door in five minutes. Thus, as one conseqence, the extremely high value traditionally placed on physical evidence of virginity at time of marriage.

Could it really have been like that? Could it still be like that in the Islamic world and elsewhere today? One reason I think this question demands some attention is that the costs of the customs required to restrain female sexuality under this model are quite high on many levels. At minimum you have to prevent sex mixing, which is not merely unpleasant for both men and women but requires everybody to invest lots of effort in the system of control (wives and daughters cannot travel or in extreme cases even go outside without male escort, homes have to be built with zenanahs). At the extreme you find yourself mutilating the genitalia of your own daughters as they scream under the knife.

I don’t think customs that expensive can stay in force without solid reason. And it’s not sufficient to fall back on feminist cant and say the men are doing it to oppress the women, as if desire to oppress were a primary motive that doesn’t require explanation. For one thing, in such cultures women (especially older women out of their fertile period) are always key figures in the control system. It couldn’t function without them being ready to take a hard line against sexual “impurity” – often, a harder line than men do.

And, in fact, a large body of historical evidence suggests that it is possible to train most women to be uncontrollably lustful with strange men. All you have to do is limit their sexual opportunities enough, as in a system of purdah or strict gender segregation that almost totally prevents close contact with males other than close relatives.

What I’m suggesting is that the they’ll-fling-themselves-at-any-male model of female behavior believed by strict patriarchal societies is actually a self-fulfilling prophecy – that is, if your society begins to evolve towards purdah, women (who have only a limited fertile period) adapt by becoming more sexually aggressive. This in turn motivates stricter customs.

The effect is a vicious circle. At the extreme, the societies in which everyone expects women to bang strangers on five minutes’ notice find they elicit exactly that behavior with the methods they employ to suppress it. Well, except for clitoridectomy; that probably works, being your last resort when you’ve noticed that social repression is making your fertile women ever more uncontrollable when they can get at men.

We can find some support for this theory even in present time. I’ve noted before that in our modern, liberated era women seem not to be demanding as high a clearing price for sex as they should. In traditional terms, they’re being lustful. And this is in a culture that probably encourages sex mixing as much or more than any in history, driving the opportunity cost associated with not randomly humping strangers to an unprecedented low.

I’m not writing to suggest any particular thing we should do about this. What I’m encouraging is a variant of the exercise I’ve previously called “killing the Buddha”. Sometimes the consequences of supposing that our ancestors reported their experience of the world faithfully, and that their customs were rational adaptations to that experience, lead us to conclusions we find preposterous or uncomfortable. I think that the more uncomfortable we get, the more important it becomes to ask ourselves “What if it really was like that?”