I expect you kind of see where this is going.
I have to make some things up that can't be checked scientifically, so one of my inventions for purposes of this novel is pheremones, that scent that Linda occasionally notices from Hugo. It's a fact that individuals tend to have a unique odor. Your dog will pick it up a lot quicker than you will, but some people are especially sensitive to such things, and early humans would have been more so that modern ones since their noses weren't continuously assaulted by the smells (make that stinks) of urban living. So the pheremones put out by the men and women of that era would have had powerful significance relative to such things as mating. That, at least, is my postulate.
The time spans I mention-how long it's been since modern-day homo sapiens evolved, how long since agrarian civilization arose-are scientifically accurate. Recorded history began some time after agricultural progress first allowed humans to gather into stable and enduring communities, where writing became a necessary adjuct to the trade that those communities permitted and encouraged. We retain, of course, only a fraction (and mostly the more recent, relatively speaking) of the records that were created at that time.