He has shown that among those peoples bifurcate merging systems tended to get transformed either into bifurcate collateral, or generational ones. On the other hand, the lineal kinship terminology developed either from bifurcate collateral ones (this development is most typical for Eurasia), or from generational systems.
He has shown that the evolution of merging systems among specific populations resulted in either bifurcate collateral or generational systems.  Lineage terminology developed either from bifurcate collateral systems (most prevalent in Eurasia) or generational systems.