I just recently finished the sixth and final installment of Jean Auel's Earth Children series, and I've concluded it's a subversive book. No, not because it takes place on an Earth more than six thousand years old, not because it depicts goddess worship in a pre-Christian world, nor because it imagines our ancestors interbreeding with Neanderthals. Not even because the first book has multiple rapes of a very young woman and the subsequent books include numerous and often detailed sexual encounters. All of that's fairly passe these days, and part of this book is definitely (though perhaps unintentionally) hitting a very contemporary sacred cow.
As Ayla is nearing the end of what I'll call her shaman training she gets her "call" (visions) and, as part of this, receives supernatural confirmation of her long-held theory that it's sex with a man that creates new life in a woman's belly. Her superior decides they must reveal this information to their people, despite the inevitable social change it will cause. Ayla thinking about this afterward considers that the knowledge will empower women: once women know babies are made by sex, they can, when it would be inconvenient or undesirable for them to get pregnant, refrain from sex.
Now that's a subversive idea.
We've been hearing since the '80s that, while knowing about contraception is good, knowing what causes babies can in no way affect our behavior. People who know full well where babies come from can not be expected to refrain from that activity just because they can't support a baby, aren't married, have important goals that would be hindered by a baby at this time, etc. Knowledge is not power when it comes to sex and babies. That's been the message for at least half my life.
I guess Ayla, being a cave woman, was too dumb to know that.