Lack of estrous cycle - lydgate/mindmeld GitHub Wiki

Humans menstruate/lack estrous cycle

Most mammals have an estrous cycle and go into heat, then have sex only during that period. The endometrium is absorbed afterwards. In primates (possibly only primates), this is not what happens; they shed the endometrium, and also they can basically have sex whenever. (Dolphins also have sex outside the estrous cycle but afaik don't have a menstrual cycle. But they also experience menopause.) In other words... human females don't show when they are fertile, as opposed to pretty much all other mammals

Possibly two shifts for humans:

Around 40k years? Venus figurines
Around 600 BC? (Pompeii shows late stuff)

Julian Jaynes:

The third example I would consider here is the affect of mating. It is similar in some respects to other affects but in other ways quite distinct. Animal studies show that mating, contrary to what the popular mind thinks, is not a necessary drive that builds up like hunger or thirst (although it seems so because of consciousness), but an elaborate behavior pattern waiting to be triggered off by very specific stimuli. Mating in most animals is thus confined to certain appropriate times of the year or day as well as to certain appropriate sets of stimuli as in another’s behavior, or pheromones, light conditions, privacy, security, and many other variables. These include the enormous variety of extremely complicated courtship procedures that for rather subtle evolutionary advantages seem in many animals almost designed to prevent mating rather than to encourage it, as one might expect from an oversimplified idea of the workings of natural selection. Among the anthropoid apes, in contrast to other primates, mating is so rare in the natural habitat as to have baffled early ethologists as to how these most human-like species reproduced at all. So too perhaps with bicameral man.

But when human beings can be conscious about their mating behavior, can reminisce about it in the past and imagine it in the future, we are in a very different world, indeed, one that seems more familiar to us. Try to imagine what your “sexual life” would be if you could not fantasize about sex.

What is the evidence for this change? Scholars of the ancient world, I think, would agree that the murals and sculptures of what I’m calling the bicameral world, that is, before 1000B.C., are chaste; depictions with sexual references are scarcely existent, although there are exceptions. The modest, innocent murals from bicameral Thera now on the second floor of the National Museum in Athens are good examples.

But with the coming of consciousness, particularly in Greece, where the evidence is most clear, the remains of these early Greek societies are anything but chaste.25 Beginning with seventh century B.C. vase paintings, with the depictions of ithyphallic satyrs, new, semidivine beings, sex seems indeed a prominent concern. And I mean to use the word concern, for it does not at first seem to be simply pornographic excitement. For example, on one island in the Aegean, Delos, is a temple of huge phallic erections.