From Oregon to the Valley of Mexico

Uto-Aztecan runs the length of western North America, from Northern Paiute in Oregon down through Shoshone, Comanche and Hopi to Wixarika, Raramuri and Nahuatl in Mexico. Around sixty languages are counted, and the family is securely established. It joins peoples whose ways of life differed as much as any on the continent, from Great Basin foragers to the urban civilisation of the Valley of Mexico, in a single lineage, and the direction in which it spread has been argued over for a century. One account has the family originating in the Great Basin and moving south, the other has it originating in northwest Mexico and moving north with maize agriculture.

The stakes are not narrowly linguistic: the answer bears on whether farming spread through the southwest by migration or by adoption, which is one of the central questions of North American archaeology. Hopi is the outlier in more than geography. It is spoken in the Pueblo southwest among neighbours from three unrelated families, which is a reminder that a language family is not a culture area and that peoples who share a way of life need not share an ancestor. The reverse holds too. Comanche and Nahuatl belong to one family and their speakers shared almost nothing: a mounted plains people of the southern United States and the urban population of the largest city in the pre-conquest Americas. A family tree records descent of speech and nothing else, and reading it as a chart of cultural affinity is the commonest mistake made with these entries.