SALT LAKE CITY--(BUSINESS WIRE)--An international team of genetic scientists has discovered the ancestors of Native Americans had at least 15 unique maternal genetic lines, many more “founding mothers” than had been expected for the Paleo-Indians who initially immigrated into the unpeopled, resource-rich Western Hemisphere 15-18,000 years ago.
The study will be published online today in Genome Research (http://genome.cshlp.org/) and is entitled, “The initial peopling of the Americas: A growing number of founding mitochondrial genomes from Beringia.”
Researchers for the first time in this paper presented every known maternal Native American lineage, including some so rare only a single DNA sample exists. Collaborating on the study were scientists from the Sorenson Molecular Genealogy Foundation (SMGF), a non-profit foundation that has built the world’s largest collection of integrated genetic and family history information, the department of genetics and microbiology at the University of Pavia, Italy, and others.
The scientists also “data-mined” genetic databases of modern humans—primarily the SMGF database containing more than 110,000 samples—to expand the number of DNA samples analyzed and help answer the enigmatic question of who first populated the Americas.
“We found previously undetected founding lineages by looking at mitochondrial DNA sequences at the highest attainable level of resolution,” said Ugo Perego, Ph.D., the paper’s lead researcher and director of operations at Sorenson Molecular Genealogy Foundation (SMGF). “We thought there were only six, but now we have learned there are at least 15.”
In earlier research the same scientific team found that approximately 95 percent of modern Native Americans descended from six ancestral founding mothers. Building on that data in this study and using many more DNA samples—thanks to the SMGF database—researchers found one of those six lineages needed to be split into two. Then, studying rarer lineages in previously unavailable quantity and detail, they identified a total of 15 maternal founders and listed the frequencies with which each of those DNA lines appear in today’s populations of North-, Central- and South America.
“This study brings maternal founding lineages of Native Americans to a number considered implausible only a short time ago,” said Prof. Antonio Torroni, one of the study’s corresponding authors heading the University of Pavia group. “It also indicates the number of women with distinct mitochondrial genomes who entered the Americas from Beringia or later from eastern Siberia when the land bridge was covered by water, was much higher.”
The researchers found they could identify unique Native American maternal lineages using DNA samples from databases of both mixed-heritage and indigenous American populations, and that this method is as accurate as using only samples directly from Native American groups. “As our study’s methodological approach is systematically applied, I am sure more undiscovered lineages will be identified within the next three to four years,” said Torroni.
In March 2008, the international research group was the first to compile all known Native American mtDNA genomes into a single genetic tree with branches dated. Their Jan. 2009 study strongly suggesting that the first Paleo-Indian groups immigrating into the Western Hemisphere came not from a single population source but from distinct genetic groups, made the cover of Current Biology.
The SMGF database is the world’s most diverse collection of DNA and ancestry information and is available free of charge at smgf.org. The foundation also offers genetic genealogy search and interpretation services through its for-profit subsidiary GeneTree (genetree.com).
About the Sorenson Molecular Genealogy Foundation
The Sorenson Molecular Genealogy Foundation (SMGF) is a non-profit research organization that has created the world’s largest repository of correlated genetic and genealogical information. The SMGF database currently contains information about more than 8 million ancestors through linked DNA samples and pedigree charts from more than 170 countries, approximately 90 percent of the nations of the world. The foundation’s purpose is to foster a greater sense of identity combined with a sense of belonging among all people by showing how closely we are connected as members of a single human family. For more information about the foundation’s free, publicly available database, visit www.smgf.org.
GeneTree (www.genetree.com), a wholly owned subsidiary of the non-profit Sorenson Molecular Genealogy Foundation, is a leading provider of genetic and family history services that unlock peoples’ ancestral legacy. Powered by the world’s largest, most comprehensive repository of genetic and genealogical information, GeneTree’s best-in-class genetic testing, genetic genealogy consulting and family history research enables individuals and extended families alike to dramatically extend their family trees.