Genetic Archaeology
Recent News |  Archives |  Tags |  About |  Newsletter |  Submit News |  Links |  Subscribe to GeneticArchaeology.com RSS Fee Subscribe


More Articles
Tracking down the human 'odorprint'Tracking down the human 'odorprint'

Researchers help identify cows that gain more while eating lessResearchers help identify cows that gain more while eating less

What drives our genes? Researchers map the first complete human epigenomeWhat drives our genes? Researchers map the first complete human epigenome

Scientists discover largest orb-weaving spiderScientists discover largest orb-weaving spider

A 200,000-year-old cut of meatA 200,000-year-old cut of meat

Scientists discover quantum fingerprints of chaosScientists discover quantum fingerprints of chaos

Fill 'er up - with algaeFill 'er up - with algae

Communicating person to person through the power of thought aloneCommunicating person to person through the power of thought alone

24-carat gold 'snowflakes' improve graphene's electrical properties24-carat gold 'snowflakes' improve graphene's electrical properties

Giant impact near India - not Mexico - may have doomed dinosaursGiant impact near India - not Mexico - may have doomed dinosaurs

How the Moon produces its own waterHow the Moon produces its own water

Juggling enhances connections in the brainJuggling enhances connections in the brain

Mantis shrimps could show us the way to a better DVDMantis shrimps could show us the way to a better DVD

The book of life can now literally be written on paperThe book of life can now literally be written on paper

Native Americans descended from a single ancestral group, DNA study confirms (5/1/2009)

Tags:
american indians, humans, migration
A distinct DNA signature was found among all but one of the populations shown as points 32 to 53 on this map. The Fox tribe, point 48, was the exception. But DNA samples of only 2 Fox people were tested -- too few to provide a valid result. The DNA signature was absent in all Asian groups sampled, points 1-32. -  Kari Britt Schroeder/UC Davis
A distinct DNA signature was found among all but one of the populations shown as points 32 to 53 on this map. The Fox tribe, point 48, was the exception. But DNA samples of only 2 Fox people were tested -- too few to provide a valid result. The DNA signature was absent in all Asian groups sampled, points 1-32. - Kari Britt Schroeder/UC Davis

For 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."

Note: This story has been adapted from a news release issued by the University of California - Davis

Comments:

1. AvangionQ

5/1/2009 1:03:06 PM MST

"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." ... so then, if a migration via the Bering Straights land bridge during the last ice age wasn't the source of modern day Native American populations, if you look back far enough, where do Native American populations originate from?


2. FireTag

5/1/2009 3:27:16 PM MST

Avangion0:

That's not quite what the article says. It says the Native American founders separated from Eurasians thousands of years ago, stayed together or in small enough numbers for the allele to mutate and become established in the founding population, and then the population dispersed throughout the Western hemisphere. Where the isolation occurred -- on the land bridge, in Siberia, or in North America itself -- can't be specified.

If other migrations occurred later, they were in numbers small enough and contacted the founders quickly enough to "drown in the local gene pool."


3. Hey!

5/1/2009 5:59:11 PM MST

Men have mitochondrial DNA too!


4. WHAT?

5/11/2009 1:10:40 PM MST

We don't need mitochondrial DNA we have teh power of themz Y-CHROMOSOMES


5. Hey Now!

5/14/2009 10:03:58 AM MST

"Men have mitochondrial DNA too!"

Well more precisely "men have their mom's mitochondrial DNA"


6. Rokcet Scientist

7/1/2009 2:48:47 PM MST

So we're all sissies!


7. Joe

10/27/2009 3:29:15 PM MST

"Where the isolation occurred -- on the land bridge, in Siberia, or in North America itself -- can't be specified."
I wonder if the fact that the only population with the 9-repeat allele outside of the Americas (and Greenland) is located on the Asian (western) side of the Bering Strait tends to indicate that the isolation occurred on the eastern side of the Bering Strait in the new world. Further, that this supports those arguing for a preclovis migration.

If an isolation of a sustainable population occurred many thousands of years ago in a scarcely populated section of the western Bering straight, how come those people only migrated east (into the new world) and not also west? Seems odd. One would think the center of the civilization that gave rise to the mutation was located in the new world given it's dispersion over time.


8. JD

10/27/2009 6:04:39 PM MST

After fusion of the sperm and egg, the zygote only contains mitochondria from the mother.


9. jeff

10/28/2009 12:59:13 AM MST

thats because to the west was siberia joe.


10. Moon Feathers

10/28/2009 8:48:37 AM MST

Perhaps the NA in America were survivors of a continent that no longer exists. I have often wondered if perhaps we were descendants of the continent of Atlantis, presuming it was somewhere off the shores of America to the East and that the inhabitants fled in all directions, including America both North and South. This is compatible with legends as well.


11. xznofile

10/28/2009 4:03:28 PM MST

I may be reading this wrong, but if lack of similar surrounding dna rules out selective breeding, wouldn't that also confirm random mutation (and vise-versa)? also I understand polynesians are related to tlinglit people from canada, but the 9-repeat allele says they aren't, how come?


12. Steve yo

10/29/2009 11:11:02 AM MST

Why not test in Europe or Africa for the allele? Isn't it possible the ancestors were isolated in the Americas and spread over to the western Bering from there.

Or it's possible Eurasians came to America and some went back across the Bering much later to find the population there, in the same way the Inuit found their way to Greenland.


13. NativeAmericanMe

12/13/2009 3:39:17 AM MST

Eurasian ONLY refers to the continental location NOT the DNA. ALL Native American are purely Mongoloid of origin.


Leave a Reply:

Search

New Articles
How the butterflies got their spots 2/9/2010

Study reveals potential evolutionary role for same-sex attraction 2/7/2010

An answer to another of life's big questions 2/6/2010

New research rejects 80-year theory of 'primordial soup' as the origin of life 2/4/2010

DNA testing on 2,000-year-old bones in Italy reveal East Asian ancestry 2/3/2010

MicroRNA: A glimpse into the past 2/2/2010

Like escape artists, rotifers elude enemies by drying up and - poof! - they are gone with the wind 1/29/2010

Why humans outlive apes 1/27/2010

Dolphin and bat DNA on the same wavelength 1/26/2010

Biologists explain how organisms can tolerate mutations, yet adapt to environmental change 1/24/2010

Study shows value of sexual reproduction versus asexual reproduction 1/23/2010

Some mouse sperm can identify, and even cooperate with, its brethren 1/22/2010

Rice responsible for Asians' alcohol flush reaction 1/21/2010

Most modern European males descend from farmers who migrated from the Near East 1/20/2010

Genome sequencing shows past genetic events made soybeans rich in versatile gene families 1/17/2010


Archives
February 2010
January 2010
December 2009
November 2009
October 2009
September 2009
August 2009
July 2009
June 2009
May 2009
April 2009
March 2009
February 2009
January 2009
December 2008
November 2008
October 2008
September 2008
August 2008
July 2008
June 2008
May 2008
April 2008
March 2008
February 2008
January 2008
December 2007
November 2007
October 2007
September 2007
August 2007
July 2007
June 2007
May 2007
April 2007
March 2007
February 2007
January 2007
November 2006
October 2006
September 2006
June 2005
October 2004
July 2001


Science Friends
Agricultural Science
Astronomy News
Biology News
Biomimicry Science
Cognitive Research
Chemistry News
Tissue Engineering
Cancer Research
Cybernetics Research
Forensics Report
Fossil News
Genetics News
Geology News
Nanotech News
Physics News


  Archives |  Submit News |  Advertise With Us |  Contact Us |  Links
Use of this site constitutes acceptance of our Terms of Service and Privacy Policy. All contents © 2000 - 2011 Web Doodle, LLC. All rights reserved.