A remarkable analogy with magnetism can explain how regional dialects develop, according to a new study. James Burridge of the University of Portsmouth in the UK has shown that a simple spatial model of language change reproduces a wide range of observations and predictions of linguists who study dialects in which speakers adopt the dialect they most hear. This leads to a local “alignment” similar to that of spins in a ferromagnet, and the appearance of dialect domains bounded by domain walls or “isoglosses”, to use the linguists’ term. Taking into account varying population densities makes the isoglosses spontaneously bend, reflecting relevant geographical features.