Posted on 04/29/2009 6:13:15 AM PDT by Pharmboy
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.”
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.
That's the first thing I thought of as well.
How about separate incursions over thousands of years, from the same source of people ?
Please see post #100 for additional info
I vote you call me an Amerind. Native American.Or call us by tribes. Works for me. Just don’t call me late for supper.
Thats the Sinite group. Sino means Chinese. American Indians are of the Mongoloid group. I agree with the Bible’s explanation.
I second that.
You can find my DNA at the red cross. ;)
Yes we had these assault bows that did the dirty deed all by themselves. The Bow ban did away with it and we lived in peace and harmony with nature until the coming of the Europeans. ;)
Does this mean Amerindians are more inbred?
good!
Chickens first domesticated in Colchin
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WIKI
The chicken (Gallus gallus, sometimes G. gallus domesticus) is a domesticated fowl. Recent evidence suggests that domestication of the chicken was under way in Vietnam over 10,000 years ago.[1] Until this discovery, conventional wisdom held that the chicken was domesticated in India.[1] From India the domesticated fowl made its way to Persia. From the Persianized kingdom of Lydia in western Asia Minor, domestic fowl were imported to Greece perhaps as late as the fifth century BCE.[2] Fowl had been known in Egypt since the 18th Dynasty, the “bird that lays every day” having come to Egypt, according to the annals of Tutmose III, as tribute from from the land between Syria and Shinar, that is Babylonia.[3] Fowl make no appearance in the Old Testament.
Dunno. How about American straight up? Unless you do as my tribe does - trace lineage via the mother. So if someone had a “green” father and a “blue” mother; then that person would claim “blue”.
Every time one reads these threads about the origins of one group or another, what is generally overlooked, is the the successful group, killed all of the other group that they could get their hands on. Early humans do not appear to like strangers. So the first groups to North-South America appear to have “displaced” the earlier settlers. And it also appears to have been true in Europe-Asia. IMHO
We later ones ain't too keen on them either!
There is a part of our brain (the fusifrom gyrus of the temporal lobe--about the size of the end of your thumb--and parts of the frontal lobe) that are involved in facial recognition. To give that much precious room in our noggins to this function is evidence of how important it is.
For other races, evidence shows that it does not work as well in that it is more difficult for whites to tell blacks and Asians from each other (and vice versa).
And the answer as to why this is would be simple: we need to be able to tell strangers apart quickly (for safety reasons--friend or foe?) among people who look like us, so these neural circuits work optimally. A white tribesman or woman would immediately know that a black or Asian were of a different tribe so our brains do not need to work that hard.
I did a brief search of Chippewa and Ojibway and it looks like these groups were involved when looking for haplogroup X.
I also saw the History Channel program “10,000 BC” but as is the case with most of these programs the information they used was dated.
Not long ago X was thought to be a European phenomenon. Now it is known to be worldwide and consist of two sub groups. AFAIK the New World X is haplotype X2a and is not seen anywhere else nor is it a descendant of one of the European haplotypes.
Of course, there can always be new finds but I didn’t see any concerning another source of haplogroup X for NA. If there is I’m interested in reading about it.
My previous response doesn’t make sense. I’ll try again.
There were 908 total people spread among 44 NA groups. A percentage of them had the allele. The people who constituted that percentage were spread among the 44 groups. Therefore the groups all have the same allele in their genome (even if all individuals don’t have it). The allele is distinctive enough to assume it is identical by descent.
The calculation to the most recent common ancestor gives a date as early as 39,900ybp which would make this the result of a single founder population.
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