Bayesian parametric estimation shows the effects of social prestige and bilingualism on reshaping language competition.

Understanding the mechanisms of language competition is crucial for mitigating language extinction and promoting cultural sustainability. Nevertheless, how to quantify the effects of socio-linguistic factors, such as social prestige and bilingualism, on language competition remains a critical challenge. Here, we present Markov-process-based language competition models to explore the interactions among monolingual and bilingual groups. Based on these models, we develop a Bayesian parametric estimation strategy, which enables quantifying the effects of socio-linguistic factors through rigorous statistical examinations. With six empirical cases worldwide, we observe a general trend of minority monolinguals shifting towards majority ones, where the presence of bilingualism can decelerate this shift. Typically, bilingualism can sometimes accelerate the reverse shift when the majority language possesses a higher social prestige than the minority one. Our findings emphasize the protective role of bilingualism in mitigating language extinction, particularly when competing languages exhibit distinct social prestige. We expect that our Bayesian computational framework could serve as a useful tool for assessing the roles of socio-linguistic factors in language competition and aiding language preservation and cultural sustainability.