Andrés Reséndez

Evaluating the Farming/Language Dispersal Hypothesis with genetic variation exhibited by populations in the Southwest and Mesoamerica

The Farming/Language Dispersal Hypothesis posits that prehistoric population expansions, precipitated by the innovation or early adop-tion of agriculture, played an important role in the uneven distribution of language families recorded across the world. In this case, the most widely spread language families today came to be distributed at the expense of those that have more restricted distributions. In the Americas, Uto-Aztecan is one such language family that may have been spread across Mesoamerica and the American Southwest by ancient farmers. We evaluated this hypothesis with a large-scale study of mitochondrial DNA (mtDNA) and Y-chromosomal DNA vari-ation in indigenous populations from these regions. Partial correlation coefficients, determined with Mantel tests, show that Y-chromosome variation in indigenous populations from the American Southwest and Mesoamerica correlates significantly with linguistic distances (r = 0.33–0.384; P < 0.02), whereas mtDNA diversity correlates significantly with only geographic distance (r = 0.619; P = 0.002). The lack of correlation between mtDNA and Y-chromosome diversity is consistent with differing population histories of males and females in these regions. Although unlikely, if groups of Uto-Aztecan speakers were responsible for the northward spread of agriculture and their languages from Mesoamerica to the Southwest, this migration was possibly biased to males. However, a recent in situ population expansion within the American Southwest (2,105 years before present; 99.5% confidence interval = 1,273–3,773 YBP), one that probably followed the introduction and intensification of maize agriculture in the region, may have blurred ancient mtDNA patterns, which might otherwise have revealed a closer genetic relationship between females in the Southwest and Mesoamerica.

Distribution of Y chromosomes among native North Americans: a study of Athapaskan population history.

In this study, 231 Y chromosomes from 12 populations were typed for four diagnostic single nucleotide polymorphisms (SNPs) to determine haplogroup membership and 43 Y chromosomes from three of these populations were typed for eight short tandem repeats (STRs) to determine haplotypes. These data were combined with previously published data, amounting to 724 Y chromosomes from 26 populations in North America, and analyzed to investigate the geographic distribution of Y chromosomes among native North Americans and to test the Southern Athapaskan migration hypothesis. The results suggest that European admixture has significantly altered the distribution of Y chromosomes in North America and because of this caution should be taken when inferring prehistoric population events in North America using Y chromosome data alone. However, consistent with studies of other genetic systems, we are still able to identify close relationships among Y chromosomes in Athapaskans from the Subarctic and the Southwest, suggesting that a small number of proto-Apachean migrants from the Subarctic founded the Southwest Athapaskan populations.

Genetics and the History of Latin America

Ripan S. Malhi, David Glenn Smith, and Chuck Walker for their valuable comments and suggestions. We also express our gratitude to the UC Mexus–Conacyt Program and the Wenner-Gren Foundation for fi nancial support of this research. 1. The original story appeared in the U.S. News & World Report, 9 Nov. 1998. 2. On the many ripples created by the Jefferson-Hemings relationship, see Gordon S. Wood, “Slaves in the Family,” The New York Times Book Review, 14 Dec. 2003.

Line in the Sand: A History of the Western U.S.–Mexico Border

that are unfamiliar territory to many western readers, so the volume would have benefited from the addition of a detailed map to contextualize the geographical references encountered in the text. The volume includes no illustrations of the spaces or persons under consideration, although this lacuna is partly compensated by the richness of the individual contributions. And the decision in some of the chapters not to provide translations for obscure Portuguese terms is likely to confuse readers not familiar with the language. Finally, while it is clear that the publisher needed to contain the ultimate size of the book, the lack of any treatment of African communities in North America, Europe or any Francophone territory – obviously key settlement points for persons of African origin within the Atlantic system – is difficult to understand. These places are surely also of critical importance for understanding the dissemination of magical belief systems originating in Africa. However, since Parés and Sansi state that Sorcery in the Black Atlantic is intended to inspire new research, we may hope that scholars will soon consider New Orleans, Washington DC, Lisbon, London or Paris using this investigative model.