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Open Access Highly Accessed Research article

The history of the North African mitochondrial DNA haplogroup U6 gene flow into the African, Eurasian and American continents

Bernard Secher1, Rosa Fregel23, José M Larruga2, Vicente M Cabrera2, Phillip Endicott4, José J Pestano35 and Ana M González2*

Author Affiliations

1 Administrator of U6 mtDNA project at Family Tree DNA, Houston, TX, USA

2 Department of Genetics, Faculty of Biology, Universidad de La Laguna, La Laguna, Tenerife, Spain

3 Department of Genetics, Faculty of Medicine, Universidad de Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Gran Canaria, Spain

4 UMR 7206 Eco-anthropologie. Equipe “génétique des populations humaines”, Musée de l’Homme. CP139. 61 rue Buffon, 75005 Paris, France

5 Forensic Genetics Laboratory, Institute of Legal Medicine of Las Palmas, Las Palmas de Gran Canaria, Gran Canaria, Spain

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BMC Evolutionary Biology 2014, 14:109  doi:10.1186/1471-2148-14-109

Published: 19 May 2014



Complete mitochondrial DNA (mtDNA) genome analyses have greatly improved the phylogeny and phylogeography of human mtDNA. Human mitochondrial DNA haplogroup U6 has been considered as a molecular signal of a Paleolithic return to North Africa of modern humans from southwestern Asia.


Using 230 complete sequences we have refined the U6 phylogeny, and improved the phylogeographic information by the analysis of 761 partial sequences. This approach provides chronological limits for its arrival to Africa, followed by its spreads there according to climatic fluctuations, and its secondary prehistoric and historic migrations out of Africa colonizing Europe, the Canary Islands and the American Continent.


The U6 expansions and contractions inside Africa faithfully reflect the climatic fluctuations that occurred in this Continent affecting also the Canary Islands. Mediterranean contacts drove these lineages to Europe, at least since the Neolithic. In turn, the European colonization brought different U6 lineages throughout the American Continent leaving the specific sign of the colonizers origin.

Population genetics; Human evolution; Mitochondrial DNA; Haplogroup U6; Phylogeny; Phylogeography