 |
|
Native Americans Descended From a Single Ancestral Group, DNA Study Confirms
April 29, 2009For two decades, researchers have been using a growing volume of genetic data to debate whether ancestors of Native Americans emigrated to the New World in one wave or successive waves, or from one ancestral Asian population or a number of different populations.
Now, after painstakingly comparing DNA samples from people in dozens of modern-day Native American and Eurasian groups, an international team of scientists thinks it can put the matter to rest: Virtually without exception the new evidence supports the single ancestral population theory.
"Our work provides strong evidence that, in general, Native Americans are more closely related to each other than to any other existing Asian populations, except those that live at the very edge of the Bering Strait," said Kari Britt Schroeder, a lecturer at the University of California, Davis, and the first author on the paper describing the study.
"While earlier studies have already supported this conclusion, what's different about our work is that it provides the first solid data that simply cannot be reconciled with multiple ancestral populations," said Schroeder, who was a Ph.D. student in anthropology at the university when she did the research.
The study is published in the May issue of the journal Molecular Biology and Evolution.
The team's work follows up on earlier studies by several of its members who found a unique variant (an allele) of a genetic marker in the DNA of modern-day Native American people. Dubbed the "9-repeat allele," the variant (which does not have a biological function), occurred in all of the 41 populations that they sampled from Alaska to the southern tip of Chile, as well as in Inuit from Greenland and the Chukchi and Koryak people native to the Asian (western) side of the Bering Strait. Yet this allele was absent in all 54 of the Eurasian, African and Oceanian groups the team sampled.
Overall, among the 908 people who were in the 44 groups in which the allele was found, more than one out of three had the variant.
In these earlier studies, the researchers concluded that the most straightforward explanation for the distribution of the 9-repeat allele was that all modern Native Americans, Greenlanders and western Beringians descend from a common founding population. Furthermore, the fact that the allele was absent in other Asian populations most likely meant that America's ancestral founders had been isolated from the rest of Asia for thousands of years before they moved into the New World: that is, for a period of time that was long enough to allow the allele to originate in, and spread throughout, the isolated population.
As strong as this evidence was, however, it was not foolproof. There were two other plausible explanations for the widespread distribution of the allele in the Americas.
If the 9-repeat allele had arisen as a mutation multiple times, its presence throughout the Americas would not indicate shared ancestry. Alternatively, if there had been two or more different ancestral founding groups and only one of them had carried the 9-repeat allele, certain circumstances could have prompted it to cross into the other groups and become widespread. Say that there was a second allele - one situated very close to the 9-repeat allele on the DNA strand - that conferred a strong advantage to humans who carried it. Natural selection would carry this allele into new populations and because of the mechanics of inheritance, long stretches of DNA surrounding it, including the functionless 9-repeat allele, would be carried along with the beneficial allele.
To rule out these possibilities, the research team, which was headed by Noah Rosenberg at the University of Michigan, scrutinized DNA samples of people from 31 modern-day Asian populations, 19 Native American, one Greenlandic and two western Beringian populations.
They found that in each sample that contained the 9-repeat allele, short stretches of DNA on either side of it were characterized by a distinct pattern of base pairs, a pattern they seldom observed in people without the allele. "If natural selection had promoted the spread of a neighboring advantageous allele, we would expect to see longer stretches of DNA than this with a similarly distinct pattern," Schroeder said. "And we would also have expected to see the pattern in a high frequency even among people who do not carry the 9-repeat allele. So we can now consider the positive selection possibility unlikely."
The results also ruled out the multiple mutations hypothesis. If that had been the case, there would have been myriad DNA patterns surrounding the allele rather than the identical characteristic signature the team discovered.
"There are a number of really strong papers based on mitochondrial DNA - which is passed from mother to daughter - and Y-chromosome DNA - which is passed from father to son - that have also supported a single ancestral population," Schroeder said. "But this is the first definitive evidence we have that comes from DNA that is carried by both sexes."
Other authors of the study are David G. Smith, a professor of anthropology at UC Davis; Mattias Jacobsson, University of Michigan and Uppsala University in Sweden; Michael H. Crawford, University of Kansas; Theodore Schurr, University of Pennsylvania; Simina Boca, Johns Hopkins University; Donald F. Conrad and Jonathan Pritchard, University of Chicago; Raul Tito and Ripan Malhi, University of Illinois, Urbana-Champaign; Ludmilla Osipova, Russian Academy of Sciences, Novosibirsk; Larissa Tarskaia, Russian Academy of Sciences, Moscow; Sergey Zhadanov, University of Pennsylvania and Russian Academy of Sciences, Novosibirsk; and Jeffrey D. Wall, UC San Francisco.
The work was supported by NIH grants to Rosenberg and Smith and an NSF Graduate Research Fellowship to Schroeder.
University of California, Davis
"While earlier studies have already supported this conclusion, what's different about our work is that it provides the first solid data that simply cannot be reconciled with multiple ancestral populations," said Schroeder, who was a Ph.D. student in anthropology at the university when she did the research.
The study is published in the May issue of the journal Molecular Biology and Evolution.
The team's work follows up on earlier studies by several of its members who found a unique variant (an allele) of a genetic marker in the DNA of modern-day Native American people. Dubbed the "9-repeat allele," the variant (which does not have a biological function), occurred in all of the 41 populations that they sampled from Alaska to the southern tip of Chile, as well as in Inuit from Greenland and the Chukchi and Koryak people native to the Asian (western) side of the Bering Strait. Yet this allele was absent in all 54 of the Eurasian, African and Oceanian groups the team sampled.
Overall, among the 908 people who were in the 44 groups in which the allele was found, more than one out of three had the variant.
In these earlier studies, the researchers concluded that the most straightforward explanation for the distribution of the 9-repeat allele was that all modern Native Americans, Greenlanders and western Beringians descend from a common founding population. Furthermore, the fact that the allele was absent in other Asian populations most likely meant that America's ancestral founders had been isolated from the rest of Asia for thousands of years before they moved into the New World: that is, for a period of time that was long enough to allow the allele to originate in, and spread throughout, the isolated population.
As strong as this evidence was, however, it was not foolproof. There were two other plausible explanations for the widespread distribution of the allele in the Americas.
If the 9-repeat allele had arisen as a mutation multiple times, its presence throughout the Americas would not indicate shared ancestry. Alternatively, if there had been two or more different ancestral founding groups and only one of them had carried the 9-repeat allele, certain circumstances could have prompted it to cross into the other groups and become widespread. Say that there was a second allele - one situated very close to the 9-repeat allele on the DNA strand - that conferred a strong advantage to humans who carried it. Natural selection would carry this allele into new populations and because of the mechanics of inheritance, long stretches of DNA surrounding it, including the functionless 9-repeat allele, would be carried along with the beneficial allele.
To rule out these possibilities, the research team, which was headed by Noah Rosenberg at the University of Michigan, scrutinized DNA samples of people from 31 modern-day Asian populations, 19 Native American, one Greenlandic and two western Beringian populations.
They found that in each sample that contained the 9-repeat allele, short stretches of DNA on either side of it were characterized by a distinct pattern of base pairs, a pattern they seldom observed in people without the allele. "If natural selection had promoted the spread of a neighboring advantageous allele, we would expect to see longer stretches of DNA than this with a similarly distinct pattern," Schroeder said. "And we would also have expected to see the pattern in a high frequency even among people who do not carry the 9-repeat allele. So we can now consider the positive selection possibility unlikely."
The results also ruled out the multiple mutations hypothesis. If that had been the case, there would have been myriad DNA patterns surrounding the allele rather than the identical characteristic signature the team discovered.
"There are a number of really strong papers based on mitochondrial DNA - which is passed from mother to daughter - and Y-chromosome DNA - which is passed from father to son - that have also supported a single ancestral population," Schroeder said. "But this is the first definitive evidence we have that comes from DNA that is carried by both sexes."
Other authors of the study are David G. Smith, a professor of anthropology at UC Davis; Mattias Jacobsson, University of Michigan and Uppsala University in Sweden; Michael H. Crawford, University of Kansas; Theodore Schurr, University of Pennsylvania; Simina Boca, Johns Hopkins University; Donald F. Conrad and Jonathan Pritchard, University of Chicago; Raul Tito and Ripan Malhi, University of Illinois, Urbana-Champaign; Ludmilla Osipova, Russian Academy of Sciences, Novosibirsk; Larissa Tarskaia, Russian Academy of Sciences, Moscow; Sergey Zhadanov, University of Pennsylvania and Russian Academy of Sciences, Novosibirsk; and Jeffrey D. Wall, UC San Francisco.
The work was supported by NIH grants to Rosenberg and Smith and an NSF Graduate Research Fellowship to Schroeder.
University of California, Davis
Native Americans Current Events and Native Americans News RSSAtlanta's Fernbank Museum tracks infamous conquistador through southeast
Archaeologists at Atlanta's Fernbank Museum of Natural History have discovered unprecedented evidence that helps map Hernando de Soto's journey through the Southeast in 1540.
Size of fat cells and waist size predict type 2 diabetes in women
When it comes to assessing risk for type 2 diabetes, not only do waistlines matter to women, but so does the size of their fat cells.
As ash borer claims more trees, researcher at ISU works for species survival
Mark Widrlechner may someday be known as the modern-day Johnny Appleseed for ash trees.
Ancient Connection: Evidence from Summer Digs Points to Shawnee Lookout as Oldest Continuously Occupied Site
The discoveries continue to surprise for a team of UC students digging in Shawnee Lookout Park, with a major new mound being located and a rare kiln used to fire pottery excavated in recent weeks, along with even more evidence emerging to support the theory that the site could be the largest continuously occupied hilltop Native American site in the United States.
Invisible Ink? What Rorschach Tests Really Tell Us
One of the most well-known psychological tools is the Rorschach Inkblot Test. A viewer looks at ten inkblots, one at a time, and describes what they see.
Video game minority report: Lots of players, few characters
If the future of entertainment is interactive media, some minorities are still headed back to the past.
Study finds new evidence of periodontal disease leading to gestational diabetes
A new study by NYU dental researchers has uncovered evidence that pregnant women with periodontal (gum) disease face an increased risk of developing gestational diabetes even if they don't smoke or drink, a finding that underscores how important it is for all expectant mothers - even those without other risk factors - to maintain good oral health.
New research reveals how cranberry products prevent urinary tract infections
Chemicals present in cranberries-and not the acidity of cranberry juice, as previously thought-prevent infection-causing bacteria from attaching to the cells that line the urinary tract, as documented in a report published in Journal of Medicinal Food, a peer-reviewed journal published by Mary Ann Liebert, Inc.
Biologists solve mystery of black wolves
Why do nearly half of North American wolves have black coats while European wolves are overwhelmingly gray or white? The surprising answer, according to teams of biologists and molecular geneticists from Stanford University, UCLA, Sweden, Canada and Italy, is that the black coats are the result of historical matings between black dogs and wild gray wolves.
'Stroke Belt' Deaths Tied to Non-Traditional Risk Factors
Southerners die from stroke more than in any other U.S. region, but exactly why that happens is unknown. A new report by researchers at the University of Alabama at Birmingham (UAB) and the University of Vermont underscores that geographic and racial differences are not the sole reasons behind the South's higher stroke death rate.
More Native Americans Current Events and Native Americans News Articles
 |
Native American tribes Map Art Print POSTER Indians OOP - 20" x 16" by Poster Revolution |
 |
North American Indian (DK Eyewitness Books) by David S. Murdoch (Author) |
 |
Biography: Native American Legends They fought hard to protect the lands where they had lived and thrived since time immemorial. Thrill to these larger-than-life, legendary men whose very names conjure brave and ferocious warriors whose unrelenting stamina and indomitable spirit continues to inspire and awe throughout the ages. Learn of their exploits, strategies and stunning victories at the Battle of Little Big Horn and other legendary conflicts of the Old West. |
 |
North American Indians (Pictureback(R)) by Douglas Gorsline (Author) Illus. in full color. Describes more than a dozen American Indian tribes. |
 |
Native American Style Killer Whale Red Black Wool Indian Blanket by Pacific Blanket & Trading Co This fine woolen blanket is one of several styles that were commissioned under the careful supervision by members of the Salish Tribe. It features the KILLER WHALE in reversible black and red pattern in the west coast Native American tradition. |
 |
NATIVE AMERICANS - A TRIBUTE Starring: None Directed By: James Stewart Also With: Native American Productions by Stewart & Clark (Producer), James Stewart & Wayne Clark (Writer) NATIVE AMERICANS - A TRIBUTE pays homage to Native Americans, examining their history, culture, and traditions through narration, music, and the paintings of George Catlin, Charles Bird King, and the amazing photographs of Edward S. Curtis. Four chapters include: 1. IN THE BEGINNING (15:32) 2. A GATHERING OF NATIONS (8:25) 3. WARS & RUMORS OF WARS (19:38) 4. NATIVE AMERICANS IN THE 20TH CENTURY (28:24) The DVD traces the early history of Native Americans and continues through the twentieth century, culminating with the opening of the National Museum of the American Indian in 2004. Total Run Time: 1 hr. 15 min. This product is manufactured on demand using DVD-R recordable media. Amazon.com's standard return policy will apply. |
 |
The Wisdom of the Native Americans by Kent Nerburn (Editor) This collections of writings by revered Native Americans offers timeless, meaningful lessons and thought-provoking teachings on living and learning. |
 |
Native American Designed Hoop Dancer Earrings by Relios, Inc. Native American designer Roderick Tenorio highlights the circle of life in his gracefully crafted sterling silver and 14k gold Hoop Dancer Earrings. Dangling from sterling ear wires, three hoops entwine in playful elegance. Echoing the Southwestern spirit, a blue turquoise cabochon accentuates the middle hoop and a 14k-gold moonface graces the top hoop. Measuring 2 3/8" long x 5/8" wide, our earrings are made with pride in New Mexico, USA |
 |
10 Indian Commandments POSTER Native American history 16" x 20" by Poster Revolution 10 Indian Commandments POSTER Native American history 16" x 20" |
 |
Haunted House Child's Native American Princess Costume, Small by Rubies - Domestic Native American "Indian" Princess Childs Costumes Childs Costume includes: dress and waist sash |
| © 2009 BrightSurf.com |