Linguistic Diversity in the very Long Run

The emergence of language is one of the defining events of the human race. The subsequent development and evolution of languages, over the long sweep of history, reflect political, military, cultural, social and economic forces. The current article offers a highly parsimonious theoretical explanation of the endogenous creation and destruction of distinct languages, focusing purely on the interaction of economic and linguistic forces. Specifically, the article presents an endogenous growth model in which language is an engine of growth: agents who can communicate easily are able to produce and consume more. At the same time, economic interaction among agents affects the evolution of language communities. The resulting strategic complementarities lead agents to form distinct linguistic communities of varying sizes. Larger groups are more productive, so the model generates persistent divergence of output. The model can match a pattern that has been posited as a stylised fact of long-run historical linguistics: a global increase, and subsequent decline, in linguistic diversity. The theory is also broadly consistent with evidence on the size distribution of languages and on the relationship between mobility and linguistic diversity.