The Sons And Daughter Of...

Poul Anderson, The Shield Of Time (New York, 1991).

The Tulat/We lived in small groups but, once a year, met and "...freely made love." (p. 172)

And Corwin the anthropologist mentions that the Siberian invaders:

"'...haven't the free and easy sexual mores of the Tulat.'" (p. 196)

This has to mean that, after the annual meeting, Tula women return to their small groups not yet knowing whether they have been impregnated or, if so, by whom. So how does Aryuk, the leader of his small group, not only know who his sons and daughter are but live in the same group as them? Is Poul Anderson reading familiar family relationships back into an earlier period?

For what it is worth, my understanding of the earliest human societies and their development is as follows:

unrestricted sexuality within the tribe;
initially, no knowledge of the male role in reproduction;
then, no way of knowing which man was the father of which child;
matrilineal descent;
sexual division of labor because pregnant or breast-feeding women could not easily creep or run after animals but could gather the regular diet of nuts and fruit as against the occasional luxury of meat;
increasing sexual taboos for sound biological reasons;
the pairing marriage, a free and equal partnership, revocable at any time, between a man and a woman with no common ancestress;
tribes able to survive the loss of most men but not of most women;
productivity of labor too low for any individual or group to enslave another;
thus, captured enemies adopted or killed, not enslaved;
herding replacing hunting;
some men accumulating wealth in the form of herds and slaves (this now makes sense) to tend them;
patriarchal monogamy in which men, having overthrown matrilineal descent, can identify legitimate male heirs of their wealth.

The Tulat seem to be at the first stage.