Clan kinship and totemism.
The same argument seems to demonstrate that the idea of kinship within the clan was prior to the idea of descent from a common ancestor, whether an animal or plant, a god, hero or nicknamed ancestor.

Because it is obvious that a set of persons otherwise unconnected could not suddenly and without reason have believed themselves to be descended from a common ancestor and hence related.

If a number of persons not demonstrably connected by blood believe themselves to be akin simply on account of their descent from a common ancestor, it can only be because they are an expanded family, either actually or by fiction, which really had or might have had a common ancestor.

That is, the clan tracing its descent from a common ancestor, if this was the primary type of clan, must have been subsequent to the family as a social institution.

But as already seen the sentiment of kinship within the clan was prior to that within the family, and therefore the genesis of the clan from an expanded family is an impossible hypothesis; and it follows that the members of the clan must first have believed themselves to be bound together by some tie equivalent to or stronger than that of consanguineous kinship, and afterwards, when the primary belief was falling into abeyance, that of descent from a common ancestor came into existence to account for the clan sentiment of kinship already existing.