After noticing that there are no cross-cultural phylogenetic studies of grandparent terminologies, the authors use the record from 134 Pama-Nyungan languages to explore the evolution of this kinship category and to evaluate the effects of social structures in this evolution. The authors suggest that there used to be four different terms for grandparents in the proto-Pama-Nyungan language family, which was supported by the data. The results show no evidence of co-evolution between these grandparent systems with neither community marriage organization nor post-marital residence. There is not a significant correlation between grandparent and cross-cousin terms; however, there is some evidence that grand-child terms are correlated to grandparent systems.