SALT LAKE CITY & PAVIA, Italy--(BUSINESS WIRE)--In the most comprehensive study to date on the genetic origins of Native Americans, an international research team confirmed that Native Americans who descended from ancestors who crossed from Asia to the Americas approximately 20,000 years ago are offspring of six founding, or ancestral, mothers. The study also confirms the presence of genetic subgroups of more rare, less known and geographically limited genetic groups who arrived later. This study is the first time all known Native American mitochondrial DNA (mtDNA) sequences and lineages have been compiled, corrected and organized into a single tree with branches dated.

Researchers from the Sorenson Molecular Genealogy Foundation (SMGF), a non-profit foundation building the world's largest collection of integrated genetic and family history information, the department of genetics and microbiology at the University of Pavia, and others today published online at the Public Library of Science (www.plos.org) the results of their study of more than 200 full mtDNA sequences from Native Americans. mtDNA traces maternal ancestry for both men and women and is inherited exclusively from mothers.

Researchers combed GenBank, the National Institutes of Health genetic sequence database, and earlier scientific publications for scans of Native American mitochondrial lineages and added previously unpublished sequences to this work, said study co-author Ugo Perego, director of operations at SMGF. The genetic sequences are pan-American, including native North, Central and South American populations.

"This is the first comprehensive overview of the principal pan-American branches of the Native American mtDNA tree," said Antonio Torroni, study co-author heading the University of Pavia group. Torroni is considered one of the fathers of genetic research on Native Americans and was the first to discover, 15 years ago, the four major genetic groups to which 95 percent of Native Americans belong.

The study released today identifies the six surviving Native American mtDNA lineages that are dated to approximately 20,000 years ago, designated as A2, B2, C1b, C1c, C1d and D1. Today's study also confirms the presence of five more rare, less known and geographically limited genetic groups: X2a, D2, D3, C4c and D4h3.

The five more rare genetic groups will help researchers isolate branches within the pan-American groups that are younger or come from a better-defined geographic area, said lead author Dr. Alessandro Achilli, researcher at the University of Pavia and assistant professor at the University of Perugia. "For example, we learned one branch is only found among Aleuts and Eskimos," he said. "The presence of these additional subgroups suggests different migratory events from Asia or the Bering Straits. This study will be used as a reference for all future research on Native Americans. It is essential for reconstructing the history of specific Native American groups and for reliable association studies between mtDNA haplogroups and complex disorders," said Achilli.

Comprehensive data from the study is available online at www.plos.org, said Perego, and may be used to improve tests by commercial genetic genealogy firms, such as GeneTree. GeneTree (www.genetree.com) is a DNA-enabled family history-sharing Website helping people understand where their personal histories belong within the greater human genetic story. GeneTree was developed by the Sorenson family of companies and draws on the expertise of the Sorenson Molecular Genealogy Foundation.

People are increasingly using genetic testing to learn about their roots, said Perego. "I receive calls and emails regularly asking, 'With a DNA test, can you prove I have Native American ancestry?' Our new research has the potential to fine-tune genetic genealogy tests for these people." He noted genetic testing is not currently accepted as proof of ancestry for admission into a tribe.

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Gretchen Holbrook Gerzina was two years into researching her newest book, detailing the lives of an influential 18th-century African-American married couple, when she uncovered a shameful part of her own past.

In what first started as an effort to fulfill academic curiosity, Gerzina, a professor at Dartmouth College and the first black woman to chair an English department at an Ivy League school, found herself on a quest for redemption.

When she started digging into the past for Mr. and Mrs. Prince, Gerzina, whose mother is white and a practicing genealogist, discovered that her direct ancestor was related to the man who owned Abijah (rhymes with Elijah) Prince, the husband of Lucy Terry, both the subjects of Gerzina's book. A "quiet amazement" fell over Gerzina and her family when her mother put all the pieces together. Guilt immediately followed.

"I felt ashamed that my family could do this, and I felt it was really my job to find out everything I could about the Princes," Gerzina says. "I felt morally obligated."

So she and her husband, Anthony, spent seven years traveling all over New England in search of elusive information about Terry and Prince, who owned land in Massachusetts and Vermont as freed slaves in the mid- to late 1700s.

Terry, who is widely credited with writing the first English poem by a black American, had argued successfully in front of the Vermont Supreme Court to keep her land, and both distinctions solidified her place in American history. Still, little was actually known about her life or her husband's life besides the legend that had been passed down over the generations.

Gerzina found out that as a 12-year-old slave, Abijah Prince was given as a gift to Benjamin Doolittle, a newly ordained minister just out of college who eventually freed Prince and helped him acquire land. A 20-year-old schoolteacher named Lydia Todd married Doolittle shortly afterward, sparking Gerzina's connection to the story. Gerzina, who knew she descended from the Todds, checked the name against her family genealogy that her mother had compiled years earlier, and Gerzina discovered that she was a direct ancestor of Todd's uncle.

Lucy Terry is best known for composing Bars Fight, a poem she wrote when she was a slave about a devastating Indian raid that killed five people in her hometown of Deerfield, Mass., in 1746. But her words had survived only in oral tradition until the poem was first published more than a century later. Reanna Ursin, an assistant professor with a specialty in African-American literature at McDaniel College in Maryland, says Terry's poem is important because it shows she was more than simply literate.

"There is an artistry to her poem of stressed and unstressed syllables," Ursin says. "It's not as though she was simply rhyming haphazardly."

To Gerzina, the poem provides a window to the life of a slave — a life, she says, many people still know little about.

"She was a member of this town and wrote about it to show she was as significantly upset and concerned as everyone else," Gerzina says. "It made me feel African-Americans, freed or slaved, were still part of the fabric of the towns where they lived."

In trying to understand more about Terry's world, Gerzina visited the places she and her husband called home. Gerzina spent countless hours poring over court records, town histories and genealogies.

Tracing back such a detailed history always requires perseverance and a bit of serendipity, especially when dealing with slave records, says Tony Burroughs, an expert in African-American genealogy.

"Sometimes you need some luck. That has a role in it," says Burroughs, who explains that early records for black Americans were often segregated or, in many cases, never existed.

Gerzina never meant to spend more than one year on the book, let alone seven, and she believes she will continue her research if new information about Prince and Terry surfaces. After all the research, there are still details of their lives that remain a mystery to Gerzina, such as how Terry was granted her freedom. But to Gerzina, her book tells more than just a personal story. To her, it sheds light on a piece of early American history not often discussed.

"We think of slavery not being in places. We certainly don't think about it in Vermont," she says. "We want people to rethink what early America was like and what it felt like to live here."

Gerzina suspects she will always feel guilty about her ancestors but believes she has honored the legacies of Abijah Prince and Lucy Terry by piecing together the details of their lives for others to understand their historical significance.

"In some ways, it took my finding the family connection to keep me on track for so long," she says. "In the end, I brought back to the world a story that really needed to be known about them."