Mitochondrial DNA and Prehistoric Settlements: Native Migrations on the Western Edge of North America

Human Biology, Feb 2004 by Eshleman, Jason A, Malhi, Ripan S, Johnson, John R, Kaestle, Frederika A, Et al

The vast majority of unadmixed modern Native Americans are members of one of five maternal founding lineages or haplogroups, designated as haplogroups A, B, C, D, and X (Brown et al. 1998; Forster et al. 1996; Schurr et al. 1990; Torroni et al. 1993). These haplogroups are readily distinguished by the gain or loss of one or more restriction sites or, in the case of haplogroup B, by the presence or absence of a 9 base pair deletion in the COII-tRNA^sup lys^ intergenic region (Schurr et al. 1990) and are associated with corresponding point mutations in the control region (CR) of the mtDNA (Torroni et al. 1993). Each haplogroup can be further divided into multiple discrete haplotypes, or groups of closely related haplotypes, on the basis of additional CR mutations (Torroni et al. 1993).

In North America the distribution of the five haplogroups is decidedly nonrandom, and significant regional patterning exists (Lorenz and Smith 1996; Smith et al. 1999). Studies of ancient mtDNA diversity in North America reveal that Native American haplogroup frequency distributions in some regions exhibit marked temporal and regional continuity (Carlyle et al. 2000; O'Rourke et al. 2000). Carlyle et al. (2000) demonstrated that the haplogroup frequency distribution of ancient human remains associated with the Anasazi cultural tradition in the American Southwest is not significantly different from that of modern Pueblo populations, such as the Zuni. This study provides biological and cultural evidence for unbroken ancestor or descendant relationships in the American Southwest, spanning at least the last 2000 years. In contrast, Kaestle and Smith (2001) demonstrated that ancient western Great Basin populations are genetically dissimilar to modern populations in the same region, probably because of a population spread of Numic speakers into the Great Basin from Southern California approximately 1000 years B.P. (Bettinger and Baumhoff 1982).

Although on a general worldwide level there is a relatively high correspondence between genes and language (Cavalli-Sforza et al. 1992), this relationship might not hold on more local levels (Shields et al. 1993; Ward et al. 1993). Some Native American populations that lack close linguistic ties in the Pacific Northwest share similar haplogroup frequency distributions and several distinct mtDNA haplotypes (Ward et al. 1993), but most Native American populations in western North America have not been studied. Similarly, Uto-Aztecan-speaking and Yuman-speaking populations in the Southwest share similarities in their mtDNA without any apparent close linguistic ties (Lorenz and Smith 1996; Malhi et al. 2003).

The present study uses mtDNA to investigate the genetic relationships among a broader range of populations in western North America, an area lhat exhibited considerable linguistic diversity at the time of European contact. Because the patterning of this linguistic diversity has been used to generate hypotheses of prehistoric population movements and expansions, we examine the distribution of mtDNA haplogroups and haplotypes in the context of this linguistic diversity and the archeological record.