Equilibrium and punctuation

A. The linguist R. M. W. Dixon has argued influentially that the development of language areas is a norm. The typical situation worldwide has been that groups of languages spoken by small numbers of people have coexisted for millennia, sharing words and grammar and becoming increasingly alike. This situation is one of what Dixon terms linguistic equilibrium, in which it is rare that new languages develop.

B. However, invasions, migrations, and geographical upheavals sometimes lead speakers of a language to move to other regions, replacing the languages of previous inhabitants. The new groups of speakers, separated from the original ones, develop new branches of the original language in each new location. Dixon terms this punctuation, modeled on the evolutionary theory of paleontologists Niles Eldredge and Stephen Jay Gould that evolution proceeds in abrupt leaps rather than tiny steps. Under Dixon’s theory, the branching of a language into new ones is a special circumstance, a leaping kind of change distinct from the relative stasis of an equilibrium situation.