Mitochondrial Population Genomics Supports a Single Pre-Clovis Origin with a Coastal Route for the Peopling of the Americas

Faculdade de Biociências, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, RS, 91619-900, Brazil.
The American Journal of Human Genetics (Impact Factor: 10.93). 04/2008; 82(3):583-92. DOI: 10.1016/j.ajhg.2007.11.013
Source: PubMed


It is well accepted that the Americas were the last continents reached by modern humans, most likely through Beringia. However, the precise time and mode of the colonization of the New World remain hotly disputed issues. Native American populations exhibit almost exclusively five mitochondrial DNA (mtDNA) haplogroups (A-D and X). Haplogroups A-D are also frequent in Asia, suggesting a northeastern Asian origin of these lineages. However, the differential pattern of distribution and frequency of haplogroup X led some to suggest that it may represent an independent migration to the Americas. Here we show, by using 86 complete mitochondrial genomes, that all Native American haplogroups, including haplogroup X, were part of a single founding population, thereby refuting multiple-migration models. A detailed demographic history of the mtDNA sequences estimated with a Bayesian coalescent method indicates a complex model for the peopling of the Americas, in which the initial differentiation from Asian populations ended with a moderate bottleneck in Beringia during the last glacial maximum (LGM), around approximately 23,000 to approximately 19,000 years ago. Toward the end of the LGM, a strong population expansion started approximately 18,000 and finished approximately 15,000 years ago. These results support a pre-Clovis occupation of the New World, suggesting a rapid settlement of the continent along a Pacific coastal route.

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    • "America to try to infer a migration route, compared the coalescence date of X2a to that of other founder haplogroups in the Americas, and examined the demographic histories of each haplogroup to see if they underwent similar evolutionary pressures (such as population bottlenecks and expansions) (Achilli et al. 2008; Fagundes et al. 2008; Kashani et al. 2012; Perego et al. 2009; Smith et al. 1999, 2005; "

    10/2015; 1(4):297-304. DOI:10.1179/2055556315Z.00000000040
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    • "After decades of intense research, the subject of the settlement of the New World continues to be highly controversial . Although it is widely recognized that America was the last continent to be populated, probably from Asia through Beringia during the last glaciations at the end of the Pleistocene, researchers' views on various aspects of this process (e.g., from where, by whom, how many times the continent has been populated) differ significantly (Lahr, 1996; Bonatto and Salzano, 1997; Santos et al., 1999; Tarazona-Santos and Santos, 2002; Bortolini et al., 2003; Schurr, 2004; Neves and Hubbe, 2005; Goebel et al., 2003; Fagundes et al., 2008; Gonz alez-Jos e et al., 2008; Marangoni et al., 2013; Raghavan et al., 2014a, 2014b, Rasmussen et al. 2014; Dixon 2013, among others). This is probably due to the fact that insights into the peopling of the Americas comes from a variety of disciplines including geology, paleoecology, archaeology, skeletal biology, and genetics, yet the models that intend to explain such different lines of evidence are often centered on only one specific data type, sometimes disregarding potentially complementary interpretations of other traits. "
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    ABSTRACT: A noticeably well-preserved ∼12.500 years-old skeleton from the Hoyo Negro cave, Yucatán, México, was recently reported, along with its archaeological, genetic and skeletal characteristics. Based exclusively on an anatomical description of the skull (HN5/48), Chatters and colleagues stated that this specimen can be assigned to a set of ancient remains that differ from modern Native Americans, the so called "Paleoamericans". Here, we aim to further explore the morphological affinities of this specimen with a set of comparative cranial samples covering ancient and modern periods from Asia and the Americas. Images published in the original article were analyzed using geometric morphometrics methods. Shape variables were used to perform Principal Component and Discriminant analysis against the reference samples. Even thought the Principal Component Analysis suggests that the Hoyo Negro skull falls in a subregion of the morphospace occupied by both "Paleoamericans" and some modern Native Americans, the Discriminant analyses suggest greater affinity with a modern Native American sample. These results reinforce the idea that the original population that first occupied the New World carried high levels of within-group variation, which we have suggested previously on a synthetic model for the settlement of the Americas. Our results also highlight the importance of developing formal classificatory test before deriving settlement hypothesis purely based on macroscopic descriptions. Am J Phys Anthropol, 2015. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.
    American Journal of Physical Anthropology 07/2015; 158(3). DOI:10.1002/ajpa.22801 · 2.38 Impact Factor
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    • "The model does gain some support from the distribution of closely related modern native populations living along the coasts of North and South America that suggest an early single entry and distribution (Fagundes et al. 2008; Reich et al. 2012). The DNA of an early burial at On Your Knees Cave dating to ∼10.3 ka suggests it is linked to these coastal populations (Kemp et al. 2007). "
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    ABSTRACT: A substantial amount of archaeological data suggests groups with markedly different lithic technologies and subsistence adaptations were widespread throughout both American continents by ∼13–13.5 ka. While there are fewer archaeological sites credibly dated to ∼13.5–15.5 ka, they are sufficient to indicate human foragers occupied at least the Pacific coasts of both continents and probably interior continental locations as well. Assuming it required at least 500–2000 years for initial populations to expand throughout these regions, the first colonists must have begun to spread throughout the Americas south of the Laurentide and Cordilleran ice sheets well before post-glacial global warming at 14.5 ka resulted in the melting of the ice sheets and a rapid rise in sea levels. The European and Asian gateway regions to the Americas were occupied by ∼35 ka, and the initial colonization likely postdates this interval. Genetic data suggest the first colonists derive from populations that occupied the Altai Mountains area of central Asia sometime before ∼24 ka, but this hypothesis is based on the modern distribution of haplogroups, and the locations of their ancestral populations at the time they diverged from parent Eurasian populations is unknown. The Altai region is equidistant from both the Atlantic and Pacific gateways to the Americas, and the direction from which the first Americans arrived is a matter of speculation. There are no empirical data supporting the genetic-based hypothesis that there was a population " standstill " in interior Beringia for thousands of years. If there was such a standstill, it more likely occurred in coastal refugia or in other areas in northeast Asia. Scattered data suggest the possibility the Americas were initially occupied sometime prior to ∼17 ka, but these need to be confirmed before they are widely accepted. Of the three most viable hypotheses for the peopling of the Americas, a Clovis First – Ice-free Corridor model appears to be dead and buried; an Atlantic Ice Shelf – Solutrean Origin model is untested, with no empirical data either supporting or falsifying the model; a Pacific coastal model may be the most viable explanation for the initial peopling of the Americas, but also has limited empirical support. This model suggests that boat-using foragers, with an adaptation to the shorelines and estuaries of the Pacific Rim, moved around the margins of the northern Pacific into North and South America before expanding into interior continental regions. Such a migration likely occurred during or prior to the last full glacial.
    07/2015; 1(3):217-250. DOI:10.1179/2055557115Y.0000000006
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