Autosomal STR Variation in Native America

This is a huge dataset from an article in PLOS Genetics. While the amount of samples and the work that went into this is impressive (it is nice that they included all of their data as supplementary figures and tables), there are a few problems. One is the small amount of Native North American samples used in this project. There are only three populations north of Mexico (Chippewa, Cree, and Ojibwa) and the data set is heavily weighted to the south I don't know if it is fully representative of Native North America. A problem with the HGDP originally was the reluctance of the Native Americans from the US to participate and this continues to this day (see this NY Time article). For a good background on the furor over the HGDP check out this issue of Cultural Survival Quarterly.

While they cite an article I wrote (how exciteing) and their data shown in figure 8 appear to supports the assumption of a separate Chibchan migration from Central America into South America they should also acknowledge Keyeaux et al. (2002) who also suggested the same migratory pattern based on mtDNA haplogroup data in Colombia. The inclusion of Zenu in Chibchan-Paezan is somewhat spurious as it is an extinct language but some linguists do include it. I'm also curious as to which Mexican Maya (there are more than one or is it an amalgamation) group they are using and why are they so different than the Kaqchikel (a Mayan group from Guatemala). The authors also mention a connection between Mesoamerica and the Andes but don't mention the fact that the Spanish moved thousands of Native Americans from Nicaragua (primarily Nicarao) and elsewhere to work in Peru during the 1600s. This is fairly well documented by Spanish historians and mixture between Indian groups over the last 400 years may have created this relationship.

Genetic Variation and Population Structure in Native Americans

Sijia Wang, Cecil M. Lewis Jr., Mattias Jakobsson, Sohini Ramachandran, Nicolas Ray, Gabriel Bedoya, Winston Rojas, Maria V. Parra, Julio A. Molina, Carla Gallo, Guido Mazzotti, Giovanni Poletti, Kim Hill, Ana M. Hurtado, Damian Labuda, William Klitz, Ramiro Barrantes, Maria Cátira Bortolini, Francisco M. Salzano, Maria Luiza Petzl-Erler, Luiza T. Tsuneto, Elena Llop, Francisco Rothhammer, Laurent Excoffier, Marcus W. Feldman, Noah A. Rosenberg, Andrés Ruiz-Linares

Abstract

We examined genetic diversity and population structure in the American landmass using 678 autosomal microsatellite markers genotyped in 422 individuals representing 24 Native American populations sampled from North, Central, and South America. These data were analyzed jointly with similar data available in 54 other indigenous populations worldwide, including an additional five Native American groups. The Native American populations have lower genetic diversity and greater differentiation than populations from other continental regions. We observe gradients both of decreasing genetic diversity as a function of geographic distance from the Bering Strait and of decreasing genetic similarity to Siberians—signals of the southward dispersal of human populations from the northwestern tip of the Americas. We also observe evidence of: (1) a higher level of diversity and lower level of population structure in western South America compared to eastern South America, (2) a relative lack of differentiation between Mesoamerican and Andean populations, (3) a scenario in which coastal routes were easier for migrating peoples to traverse in comparison with inland routes, and (4) a partial agreement on a local scale between genetic similarity and the linguistic classification of populations. These findings offer new insights into the process of population dispersal and differentiation during the peopling of the Americas.