I will confess, I can't be certain; but the romantic spirit in me prefers the latter. And I'm reminded of the bowerbird's courtship; the male constructs an elaborate bower, and decorates it with various found (or stolen) objects, preferably blue ones. The female then chooses whether he is her mate or not. Likewise, the splendid bird of paradise has the male do an elaborate courtship dance to win the female's favor. Surely, even cavemen could figure out some advantages of following the lead of these experienced courters!
Anyway, I found reference to an old movie, Quando le Donne Avevano la Coda (When Women Had Tails), starring Giuliano Gemma and Senta Berger. The plot of this oldie (1970) centers around a group of seven prehistoric guys trapping in a pit a woman who had a tail! They debate as to whether to eat her; but she teaches one some other possibilities.
Yes, it was lowbrow sexy comedy like the Italians could do it; even when the guy attempts to mate with her, heassumes a supine pose above her rather than prone! (Maybe the Missionaries did a service millenia later by giving effective coaching in this important life skill!)
If you would like to watch the original in its entirety, just go to YouTube. Warning: It's 1:42 long, in Italian, and a lot of lame humor transpires! It has a happy ending, don't fear.