Pama–Nyungan grandparent systems change with grandchildren, but not cross-cousin terms or social norms

摘要: Kinship is a fundamental and universal aspect of the structure human society. The kinship category ‘grandparents’ socially salient, owing to grandparents’ investment in care grandchildren as well older generations’ control wealth cultural knowledge, but evolutionary dynamics grandparent terms has yet be studied phylogenetically explicit context. Here, we present first phylogenetic comparative study by investigating 134 languages Pama–Nyungan, an Australian family hunter–gatherer languages. We infer that proto-Pama–Nyungan had, with high certainty, four separate for grandparents. This state then shifted into either two-term system distinguishes genders grandparents or three-term merges ‘parallel’ grandparents, which could transition different ‘cross’ find no support co-evolution these systems community marriage organisation post-marital residence. some evidence correlation grandchild terms, cross-cousin suggesting potentially form single lexical entire does not necessarily change synchronously.