Languages Evolve In Rapid Bursts,

A piece of research from my Alma Mater: Languages Evolve In Rapid Bursts, Rather Than Following A Steady Pattern: "Professor Mark Pagel from the University of Reading said “Our research suggests that rapid bursts of change occur in languages, and this reflects a human ability to adjust languages at critical times of cultural evolution, such as during the emergence of new and rival groups.

The emergence of American English took place when the American English Dictionary was introduced by Noah Webster. He insisted that ‘as an independent nation, our honor requires us to have a system of our own, in language as well as Government’. This illustrates that language is not only used as a means of communication, but it is also important for social functions, including promoting group identity and unity.”"
This is one to be careful with, though I don't really doubt that it is probably basically right. The problem is the nature of the data we are left with when dealing with linguistic archaeology: it is partial and in ways that may not reflect well what is going on in a whole speech community or the range of factors that may impinge on written language. However, it does seem likely that 'punctuated equilibrium' may apply to diachrinic language development too for the kinds of reasons hypothesised in the article.

And of course we need to take with utmost seriousness that last quoted point: that language is more than communicating facts, it's also about maintaining social solidarity and difference, identity marking, conceptual tooling ...