Robert J. Hard

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

Our understanding of the initial period of agriculture in the southwestern United States has been transformed by recent discoveries that establish the presence of maize there by 2100 cal. B.C. (calibrated calendrical years before the Christian era) and document the processes by which it was integrated into local foraging economies. Here we review archaeological, paleoecological, linguistic, and genetic data to evaluate the hypothesis that Proto-Uto-Aztecan (PUA) farmers migrating from a homeland in Mesoamerica introduced maize agriculture to the region. We conclude that this hypothesis is untenable and that the available data indicate instead a Great Basin homeland for the PUA, the breakup of this speech community into northern and southern divisions ≈6900 cal. B.C. and the dispersal of maize agriculture from Mesoamerica to the US Southwest via group-to-group diffusion across a Southern Uto-Aztecan linguistic continuum.

Mano size, stable carbon isotope ratios, and macrobotanical remains as multiple lines of evidence of maize dependence in the American southwest

While the level of agricultural dependence affects many aspects of human adaptation, estimating levels of dependence on maize through traditional archaeological techniques is problematic. Here we compare various measurements of manos (e.g., grinding surface area), macrobotanical evidence of maize use, and human collagen stable carbon isotope values from six regions of the American Southwest, encompassing 16 phases, as a means of assessing the power and limits of each approach for considering agricultural dependence. The analysis of each data class is considered separately, taking into account formation processes and arguments linking data and inferences. Correlations among the three data classes suggest that mano area and maize ubiquity can be considered ordinal measures of agricultural dependence, but Southwestern stable carbon isotope data have the analytical potential only to discriminate between little or no maize use and substantial maize use. The formation processes and linking arguments associated with each method must be considered when multiple lines of evidence are integrated in order to make sound behavioral inferences. Our results suggest that there were at least three patterns in the adoption of farming in the Southwest: early substantial use followed by continuous increasing maize dependence, initial intensive dependence with little change in later periods, and a long period of minor use followed by substantial dependence.

Reply to Hill and Brown: Maize and Uto-Aztecan cultural history

The hypothesis that Proto-Uto-Aztecan (PUA) speakers cultivated maize in or near Mesoamerica rests primarily on Jane H. Hills argument (1) that a maize-related vocabulary can be reconstructed for PUA, based on cognates in Northern Uto-Aztecan (NUA) and Southern Uto-Aztecan (SUA) languages. In our essay (2), we noted that Hill fails to demonstrate the existence of this PUA vocabulary, because the NUA words she identifies as cognates of maize-related words in SUA languages lack the expected phonological forms or the expected meanings. The same characterization applies to the additional evidence from three California NUA languages that she cites in her reply.