Native American mtDNA prehistory in the American Southwest

Abstract

This study examines the mtDNA diversity of the proposed descendants of the multiethnic Hohokam and Anasazi cultural traditions, as well as Uto-Aztecan and Southern-Athapaskan groups, to investigate hypothesized migrations associated with the Southwest region. The mtDNA haplogroups of 117 Native Americans from southwestern North America were determined. The hypervariable segment I (HVSI) portion of the control region of 53 of these individuals was sequenced, and the within-haplogroup diversity of 18 Native American populations from North, Central, and South America was analyzed. Within North America, populations in the West contain higher amounts of diversity than in other regions, probably due to a population expansion and high levels of gene flow among subpopulations in this region throughout prehistory. The distribution of haplogroups in the Southwest is structured more by archaeological tradition than by language. Yumans and Pimans exhibit substantially greater genetic diversity than the Jemez and Zuni, probably due to admixture and genetic isolation, respectively. We find no evidence of a movement of mtDNA lineages northward into the Southwest from Central Mexico, which, in combination with evidence from nuclear markers, suggests that the spread of Uto-Aztecan was facilitated by predominantly male migration. Southern Athapaskans probably experienced a bottleneck followed by extensive admixture during the migration to their current homeland in the Southwest.

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

“…Southwest populations are characterized by high frequencies of mitochondrial haplogroup B and very low frequencies, or the complete absence, of haplogroup A. The exception to this pattern is the high frequency of haplogroup A found among Southwest Athapaskan populations (Navajo and Apache) that entered the region from the north within last ∼500 years (6). As found in Results and Discussion, this population movement played little role in our understanding of the relationships between populations of the Southwest and Mesoamerica.…”

“…It has been proposed that UA speakers were, in fact, responsible for the northward spread of maize cultivation (3)(4)(5). However, previous genetic and morphologic studies have failed to provide direct evidence for an ancient spread of UA speakers (6)(7)(8).…”

“…Although studies of protein polymorphisms have identified similarities in gene frequencies between populations in the two regions (7,(30)(31)(32)(33), previous mitochondrial DNA (mtDNA) data provided no evidence of a population expansion northward from Mesoamerica (6,7). Southwest populations are characterized by high frequencies of mitochondrial haplogroup B and very low frequencies, or the complete absence, of haplogroup A.…”

“…As found in Results and Discussion, this population movement played little role in our understanding of the relationships between populations of the Southwest and Mesoamerica. In contrast to non-Athapaskan Southwest populations, Mesoamerican populations exhibit high frequencies of haplogroup A with moderate to low frequencies of haplogroup B (6,7,(34)(35)(36)(37). These haplogroup patterns crosscut linguistic and geographic boundaries within both regions, and predate European contact in the Southwest (38,39) and Central Mexico (40,41).…”

Middle Holocene climate change and human population dispersal in western North America

“…The hypothesized introduction of maize agriculture into the southwest by migrating Uto-Aztecans from northern Mexico ca. 3000 cal yr BP (Hill, 2002) is contradicted by several lines of evidence that show few similarities between modern Uto-Aztecans of the Southwest and Mesoamerica, though they share some linguistic and cultural traditions (Smith et al, 2000;Malhi et al, 2003;Kemp, 2006). In the northern Great Basin, Kaestle and Smith (2001) found genetic discontinuity between prehistoric (primarily 6000-1000 cal yr BP) populations from the Stillwater Marsh and Pyramid Lake sites and extant Northern Paiute people in western Nevada (Fig.…”