In the book she is repeatedly raped as a form of humiliation, not pleasured.
You said: In the book she is repeatedly raped as a form of humiliation
Like I said, I don't recommend the book.
The notion of setting a book in the Ice Age was kinda cool (ahem), but I didn't like it.
I was just trying to give BB an example of "primitive" people who didn't make the connection between coitus and birth. The anthropological literature (and the Straight Dope) are much better than fictional Ice Age romances.