Mitochondrial haplogroup M discovered in prehistoric North Americans

We analyzed two mid-Holocene (similar to 5000 years before present) individuals from North America that belong to mitochondrial DNA (mtDNA) haplogroup M, a common type found in East Asia, but one that has never before been reported in ancient or living indigenous populations in the Americas. This study provides evidence that the founding migrants of the Americas exhibited greater genetic diversity than previously recognized, prompting us to reconsider the widely accepted five-founder model that posits that the Americas were colonized by only five founding mtDNA lineages. Additional genetic studies of prehistoric remains in the Americas are likely to reveal important insights into the early population history of Native Americans. However, the usefulness of this information will be tempered by the ability of researchers to distinguish novel founding lineages from contamination and, as such, we recommend strategies to successfully accomplish this goal. (c) 2006 Elsevier Ltd. All rights reserved.