You have missed the most straightforward and simple logic. If it has gone over your head, well I don't know what to say. Are you trying to claim that early human kinship took the form of the modern nuclear family? and so thereby you can claim that the child's aunties in that Tomassello case should not have helped the missing child find her mother, being individualistic capitalist owners of course! Is that what you were thinking? and you accuse me of idea fixe!
Chimpanzee females (according to Tomassello cited above) have no need to point out helpful information to the child of another because it is not in their nature to do so, and so therefore they have no need of language. Human females, on the other hand took on the role of all collectively acting as mothers, the whole sisterhood raising each other's children. That's why early human kinship was matrilineal.
