  Increasing evidence demonstrates that in many places language coexistence has
become ubiquitous and essential for supporting language and cultural diversity
and associated with its financial and economic benefits. The competitive
evolution among multiple languages determines the evolution outcome, either
coexistence, decline, or extinction. Here, we extend the Abrams-Strogatz model
of language competition to multiple languages and then validate it by analyzing
the behavioral transitions of language usage over the recent several decades in
Singapore and Hong Kong. In each case, we estimate from data the model
parameters that measure each language utility for its speakers and the strength
of two biases, the majority preference for their language, and the minority
aversion to it. The values of these two biases decide which language is the
fastest growing in the competition and what would be the stable state of the
system. We also study the system convergence time to stable states and discover
the existence of tipping points with multiple attractors. Moreover, the
critical slowdown of convergence to the stable fractions of language users
appears near and peaks at the tipping points, signaling when the system
approaches them. Our analysis furthers our understanding of multiple language
evolution and the role of tipping points in behavioral transitions. These
insights may help to protect languages from extinction and retain the language
and cultural diversity.
