The evolution of cultural diversity in Pama-Nyungan Australia

Explaining the processes that produce cultural diversity has long been a focus of anthropological study. Whilst linguistic diversity has frequently been shown to be associated with population splitting during migrations, much less is known about the influence of migration patterns on other forms of culture. Here we compare variation between different cultural types to understand whether their diversity might also be a consequence of historic population change. For our case study, we developed a dataset of 90 cultural traits recorded across around 100 societies in Pama-Nyungan Australia focusing on three cultural forms important in Australian life: adolescent initiation, mortuary practice and rock art motifs. Trait diversity was analysed using phylogenetic methods and compared with language diversity since previous studies have suggested an association between Pama-Nyungan language evolution and population dispersal. We were able to demonstrate a strong association between the phylogenetic history of language and initiation ritual but not between language and mortuary ritual or rock motifs. The finding suggests population migration may have had a significant influence on initiation ritual diversity. It also lends support to the idea, as suggested by some authors, that the development of complex initiation practices may have played an active role in the dispersal of Pama-Nyungan speakers throughout the Australian continent. Our study results suggest that the type of phylogenetic comparative approach applied here can make an important contribution to the reconstruction of deep cultural history over long timescales.