Medium and Long-run Properties of Linguistic Community Evolution

We analyze a novel model of the co-evolution of linguistic community structure and language. Intuitively, agents want to communicate well with others in their linguistic community, and similarly, linguistic communities consist of those agents that can communicate effectively amongst themselves. Absent the effects of comunity structure, the model suffers from poor efficiency in the medium-run. Over the long-run, efficiency is attained, but diversity vanishes. When effects of homophily are added to the model we find a more nuanced picture. When the population size is large relative to frequency of stochastic shocks then both diversity and efficiency are observed in the medium-run, but diversity does not survive in the long-run. If stochasic shocks are more frequent then diversity and efficiency can survive the long-run.