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Paris, 11 July 2012

The genetic history of American populations

The most complete study retracing the history of the Amerindian populations' gene pool has been completed on the basis of the genetic data of 500 individuals from 52 Native American and 17 Siberian populations. The analysis, covering 364,470 genetic markers, made it possible to take into account for the first time the mixing of European and African genes within each individual. This research was carried out by a consortium of some sixty researchers from Europe and the three Americas, and particularly CNRS (1). The work, published on the 11 July 2012 on the website of the journal Nature, demonstrates that there were three separate population influxes from Siberia and that vast genetic exchanges then took place between these populations. These genetic analyses could be used in future anthropological and medical studies in America.

Using DNA chips, the most powerful technique for analyzing genomes, the researchers were able to obtain an overview of the genetic inheritance of more than 500 people from 52 Native American and 17 Siberian populations. Analysis of 364,470 genetic markers allowed them to establish the degree of genetic difference or similarity of these populations, requiring very intensive computer processing of data. In particular, it was necessary to correctly detect and interpret the genetic traces of the mixing of African and European populations that Amerindian natives underwent after the arrival of Christopher Columbus.

The analyses confirm that the majority of Amerindian people, from the Algonquin of Québec to the Yaghan of Tierra del Fuego, including the Mayas-Kaqchikel of Guatemala, stem from a migration wave from Siberia around 15,000 years ago. The genome analysis shows that the greatest genetic diversity among individuals is in North America, while the most genetically homogeneous populations are those of South America, confirming the North-South populating process of the continent.

In addition, the researchers have demonstrated the existence of two later-occurring streams of Asian gene flow. This confirms the three-wave model proposed in 1986 by Greenberg, Turner and Zegura, which, at the time, did not convince the scientific community. The two waves following that known as the “First American” wave nevertheless remained restricted to Alaska, Canada and the northern part of the United States. Contrary to the conclusions of the 1986 model, this latest data shows that the incoming populations mixed with those already present, thus forming the Eskimo-Aleut and Chipewyan peoples.

Furthermore, this research work has made it possible to resolve an enigma concerning the gene pool of Chibchan speaking Indians living in Panama. They could in fact derive from racial mixing between populations descending south from Mexico and those returning north from Venezuela and Colombia.  

This rich genetic data gathered by the consortium should lead to a large number of applications, particularly with regard to human/environment relations. For example, the two teams from the laboratories Anthropologie Bio-culturelle, Droit, Ethique et Santé and Anthropologie Moléculaire et Imagerie de Synthèse will be focusing, on the basis of these analyses, on the distribution of other genetic markers of populations who it is thought may have a selective advantage faced with certain infectious diseases in America.  

Amerindien

© Georges Larrouy

Portrait of an Amerindian from French Guiana.


Notes:

(1) Laboratoire Anthropologie Bio-culturelle, Droit, Ethique et Santé (CNRS/Aix Marseille Université/EFS) and Laboratoire Anthropologie Moléculaire et Imagerie de Synthèse (CNRS/Université Paul Sabatier Toulouse 3/Université de Strasbourg), with a financial contribution from the CNRS Amazonia Interdisciplinary Research Program.

References:

Reconstructing Native American Population History
David Reich, Nick Patterson, Desmond Campbell, Arti Tandon, Stéphane Mazieres, Nicolas Ray, Maria V. Parra, Winston Rojas, Constanza Duque, Natalia Mesa, Luis F.García , Omar Triana, Silvia Blair, Amanda Maestre, Juan C. Dib, Claudio M. Bravi, Graciela Bailliet, Daniel Corach, Tábita Hünemeier, Maria-Cátira Bortolini, Francisco M. Salzano, María Luiza Petzl-Erler, Victor Acuña-Alonzo, Carlos Aguilar-Salinas, Samuel Canizales-Quinteros, Teresa Tusié-Luna, Laura Riba, Maricela Rodríguez-Cruz, Mardia Lopez-Alarcón, Ramón Coral-Vazquez, Thelma Canto-Cetina, Irma Silva-Zolezzi, Juan Carlos Fernandez-Lopez, Alejandra V. Contreras, Gerardo Jimenez-Sanchez, María José Gómez-Vázquez, Julio Molina, Ángel Carracedo, Antonio Salas, Carla Gallo, Giovanni Poletti, David B. Witonsky, Gorka Alkorta-Aranburu, Rem I.Sukernik, Ludmila Osipova, Sardana Fedorova, René Vasquez, Mercedes Villena, Claudia Moreau, Ramiro Barrantes, David Pauls, Laurent Excoffier, Gabriel Bedoya, Francisco Rothhammer, Jean Michel Dugoujon, Georges Larrouy, William Klitz, Damian Labuda, Judith Kidd, Kenneth Kidd, Anna Di Rienzo, Nelson B. Freimer, Alkes L. Price, and Andrés Ruiz-Linares
Nature Advance Online Publication, 11 July 2012

Contact information:

CNRS researchers l Stéphane Mazières, Laboratoire Anthropologie Bio-culturelle, Droit, Ethique et Santé l T 04 91 69 88 76 l stephane.mazieres@univ-amu.fr
Jean-Michel Dugoujon, Laboratoire Anthropologie Moléculaire et Imagerie de Synthèse l T 05 61 14 59 85 l jean-michel.dugoujon@univ-tlse3.fr
CNRS press officer l Muriel Ilous l T 01 44 96 43 09 l muriel.ilous@cnrs-dir.fr

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