Stereotypes are memes, forming similarly to superstitions, in that a) whatever real-life context originally spawned them was likely exaggerated, and b) they get shared without proper understanding of said historical context.
Its hard to think of a case where a) even though clearly exaggerated had no basis in reality. This naturally dosen't automatically mean it is useful, let alone appropriate.
Before this derails, let me just say that I was claiming that in context changes in the dynamics of the sexual marketplace (changes in the attractivness of subgroups of males and females, availability of the opposite sex, ect.) would probably result in a perceptible change of stereotypes related to sexuality.
Not to mention that stereotypes present the danger of becoming self-fulfilling prophecies, in that they'll make people more likely to try to conform to them just to avoid social backlash.
This has nothing to do with thinking about whether determining whether a particular sterotype is currently true or not or even whether employing it or not as a heuristic is rational.
availability of the opposite sex, ect.
Assuming heteronormativity here, are we? :)
There was a historical shift in beliefs.
I find this very odd. How could a major cultural lineage be wrong about something so much a part of ordinary experience?
When I say wrong, I don't necessarily mean that we're right, or the ancients were right, though there's a lot of evidence that the Victorians were wrong.
My favorite theory is that people's amount of desire for sex varies sufficiently that there's enough noise to make it easy to see patterns that aren't there. I leave the possibility open that there was a change (possibly dietary) which affected libido levels differently between men and women.
People are sufficiently punitive about sex that there's going to be lies and misdirection to support the current theory about how people are supposed to be.