The diffusion of maize to the southwestern United States and its impact

Abstract

he dispersal of maize agriculture from Mesoamerica to the southwestern United States is a perennial topic of renewed interest as part of a broad, interdisciplinary effort to understand the development of maize agriculture in the New World (1–3). At present, there are two competing models of the mechanisms through which this dispersal took place. The first proposes that maize agriculture diffused northward as a complex comprised of the cultigen itself and the knowledge associated with its cultivation and use, transmitted from one foraging band to another without major population movements (4–6). The second argues that maize agriculture was introduced to the southwestern United States through the long-distance migration of Mesoamerican farmers (7–9). Over the years, most scholars have considered group-to-group diffusion more likely, but since 2000 the long-distance migration model has gained adherents due primarily to perspectives developed by the archaeologist Peter Bellwood regarding the expansion of agriculture and language families in diverse regions of the world (8, 10–14). Bellwood suggested that maize agriculture expanded from its area of origin in Mesoamerica to the US Southwest as a consequence of the migration of farmers who were members of the Proto-Uto-Aztecan (PUA) speech community. He proposed that this migration began ⬇3500 B.C. and involved the spread of PUA speakers across the region extending between Mesoamerica and the US Southwest. This population expansion www.pnas.org兾cgi兾doi兾10.1073兾pnas.0906075106