Global language diversification rates are linked to socio-ecology and extinction risk

Abstract

**Author(s):** Atkinson, Q D; Bouckaert, R B; Gray, R D; Jones, K; Kyritsis, T; Redding, D; Sheehan, O Introduction: Since Darwin it has been recognized that global linguistic diversity is the product of millennia of cultural evolution. Over half of the world’s ~6-7000 languages are now threatened with extinction, yet we know little about the drivers of language diversification or its relationship to language threat. Methods: Here, we use Bayesian phylogenetic inference techniques to generate a supertree of all extant human languages that integrates prior knowledge and uncertainty about linguistic diversification around the globe. Results: We show that lower diversification rates (and hence higher evolutionary distinctness) are linked to very high or low population density and landscape traversability, as well as to cultures that are reliant on foraging and lack political links beyond the local community. Evolutionary distinctness is also associated with greater extinction risk. Conclusions: Our findings provide insight into the forces shaping language evolution, indicate more of the evolutionary history of languages is at risk than expected under a random threat distribution, and provide cross-cultural researchers with a supertree or the world’s languages.