It has been proposed that the spread of the Numic languages (and peoples) across the Great Basin from their California homeland correlates with a shift archaeologically in the area from a hunting focus to a seed-gathering focus, and that this shift may represent a Numic replacement of the non-Numic hunters. The actual linguistic adaptations of attested foraging groups contradict this idea: linguistic homogeneity will persist over large areas where a foraging economy is practiced. This is due partly to the incest taboo (the local social organization is a form of biological family) and partly to the adaptive advantage a mutually intelligible language gives foragers when food resources fail and the local group is dispersed among kin. Linguistic diversification among foragers is maladaptive, and dialect chains among foragers may persist through millennia over vast areas. Technological shifts could easily diffuse through such networks.