Heterogeneous volatility in language shift models

Since the foundational study on language shift by Abrams and Strogatz in 2003, the field has witnessed a variety of models that employ quantitative dynamics to explore the interplay between language coexistence and extinction. Extending this research, we present a model that integrates differences in the persistence or degree of accommodation in language shift. Our model differs from traditional approaches by assigning different levels of volatility within the population. The analysis reveals that heterogeneous volatility among the population can sustain language coexistence, with the emergence of a bistable coexistence phase characterized by the simultaneous presentation of two stable coexistence solutions, underlining the important role of the non-volatile population in the prevalence of one language over the other. This work highlights the decisive influence of volatility groups and social factors in shaping the future of languages, suggesting new directions for language policy and preservation efforts.