Mitochondrial genome analysis revises view of the initial peopling of North America

Jun 28, 2010

The initial peopling of North America from Asia occurred approximately 15,000-18,000 years ago, however estimations of the genetic diversity of the first settlers have remained inaccurate. In a report published online today in Genome Research, researchers have found that the diversity of the first Americans has been significantly underestimated, underscoring the importance of comprehensive sampling for accurate analysis of human migrations.

Substantial evidence suggests that humans first crossed into North America from Asia over a called Beringia, connecting eastern Siberia and Alaska. Genetic studies have shed light on the initial lineages that entered North America, distinguishing the earliest Native American groups from those that arrived later. However, a clear picture of the number of initial migratory events and routes has been elusive due to incomplete analysis.

In this work, an international group of researchers coordinated by Antonio Torroni of the University of Pavia in Italy performed a detailed mitochondrial analysis of a poorly characterized lineage known as C1d. (mtDNA) is passed down through the maternal lineage, and mtDNA sequence markers are extremely useful tools for mapping ancestry. Similar to other haplogroups that were among the first to arrive in North America, C1d is distributed throughout the continent, suggesting that it may have been also present in the initial founding populations. However, C1d has not been well represented in previous , and the estimated age of approximately 7,000 years, much younger than the other founding haplogroups, was likely inaccurate.

To resolve these inconsistent lines of evidence, the group sequenced and analyzed 63 C1d mtDNA genomes from throughout the Americas. This high-resolution study not only confirmed that C1d was one of the founding lineages in North America 15,000 to 18,000 years ago, but revealed another critical insight. "These first female American founders carried not one but two different C1d genomes," said Ugo Perego of the Sorenson Molecular Genealogy Foundation and primary author of the study, "thus further increasing the number of recognized maternal lineages from Beringia."

These findings raise the number of founding maternal lineages in North America to fifteen. Furthermore, this work emphasizes the critical need for comprehensive analysis of relevant populations to gather a complete picture of migratory events.

Alessandro Achilli of the University of Perugia, a coauthor of the report, suggests that the number of distinct mitochondrial genomes that passed from Asian into North America is probably much higher. "These yet undiscovered maternal lineages will be identified within the next three to four years," Achilli noted, "when the methodological approach that we used in our study will be systematically applied."

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More information: Perego UA, Angerhofer N, Pala M, Olivieri A, Lancioni H, Hooshiar Kashani B, Carossa V, Ekins JE, Gómez-Carballa A, Huber G, Zimmermann B, Corach D, Babudri N, Panara F, Myres NM, Parson W, Semino O, Salas A, Woodward SR, Achilli A, Torroni A. The initial peopling of the Americas: A growing number of founding mitochondrial genomes from Beringia. Genome Res. doi:10.1101/gr.109231.110

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kevinrtrs
1.6 / 5 (7) Jun 29, 2010
I'll confess my ignorance of these DNA analyses here.

Just a small question does arise though and that is why does it seem that human beings have such a relatively short history compared to the 4.5 billion years that earth supposedly have been in existence?

And if we've been around for say 100k years, how come there's relatively so few of us around? What kind of birthrates are required to keep the human population down to such a lowly figures over such a long time?
Surely we should now be in the region of say 50 billion people[pure thumb suck] on earth given our current reproductive rates and abilities?

Just perhaps we've not been around longer than 7000 years? The current population number fits very well with that.

Am I missing something?

jsa09
3.7 / 5 (3) Jun 29, 2010
@kevinrtrs it is pretty obvious to us all that we have been around for a large part of that 4.5 Billion years. It is just that we continue to evolve over that whole period and even now continue to do so.

We have evolved over the time we have been on this planet so much that you may find it difficult to recognise your close relatives that may only have 100,000 years of differences let alone those that have accumulated several million years of differences.

Most of homo sapiens closest relatives are now long extinct. Our closest living relatives that that are not homo sapiens are the great apes and they have been evolving apart from us for well over 3 million years.
continued...
jsa09
4.2 / 5 (5) Jun 29, 2010
Survival is a perilous business and our closest relatives have not managed to do that.

So to answer your question more to the point: our subsistance population numbers is probably closer to 2 or 3 million peoples and it is only the last 10,000 years or so that different localised groups went beyond this level and suffered population explosions.

It is only in the last 100 years that crop production and industry has allowed us to support a population of 6 billion and we need more advances across the board if we are going to maintain that size for any period of time - let alone increase to 50 billion where we will have to manufacture our food in industrial complexes.
Ethelred
5 / 5 (4) Jun 29, 2010
Just perhaps we've not been around longer than 7000 years?


No. However our ancestors were dealing with the last ice age until about 10,000 years ago. Which is about the same time agriculture started.

And yes there is clear evidence that humans have been around longer than 7,000 years. Several cities may be that old. Writing is 5,000 years old, which is why some Creationists are ignoring the Bible lineages and claiming the mythical Flood was OVER 5,000 years ago instead of the 4400 that the lineages produce.

Ethelred
otto1923
3.7 / 5 (6) Jun 29, 2010
Am I missing something?
Yes, a great deal, as people have told you. And yet you continue asking questions as a way of making a point, without even realizing how stunted they make your intellect look.

Your method is called 'begging the question'.
http://en.wikiped...question

Moral: you shouldnt ask questions here unless you really want to know the answer. Or you should at least add some substance to your implications so that they may stomped on more educationally.
otto1923
3.3 / 5 (7) Jun 29, 2010
Surely we should now be in the region of say 50 billion people[pure thumb suck] on earth given our current reproductive rates and abilities?
That unbridled rate of growth would exceed the ability to organize societies and maintain stability, as it had in the distant past. Civilization would have collapsed in the interim and the ecosystem irreparably destroyed.

So your religions were created to divide the people and set them against one another in an orderly and predictable manner, so as to maintain stable growth in concert with developing technologies, without endangering civilization.

So now you know what theyre for. Death and destruction by Intelligent Design.
Caliban
1 / 5 (2) Jun 29, 2010
So- now that the YEC drivel has been dealt with, we can actually perhaps discuss some of the points raised in the article.

My opinion is that there will never be sufficient resolution through genome analysis to determine, authoritatively, the timeframe, much less the method of the populating of the New World.

The extant populations at the time of first contact with Europeans were largely eradicated by disease. The greater surviving part were killed in the process of european settlement, and the
remainder have interbred so extensively, that individuals of undiluted aboriginal heritage are very few, and in no way are they any longer representative of the genetic diversity that likely existed prior to first contact.

So that leaves us with Archeaology and the occasional fossilized or mummified remains of sufficient age to be useful in terms of providing new information.
Caliban
5 / 5 (2) Jun 29, 2010
Having said that, there is plenty of evidence, and good evidence, too- that is considered "anomalous" because it doesn't fit into the accepted paradigm of settlement(as outlined in the article)

This evidence indicates that settlement of the Americas has occurred numerous times, and over a much longer timeframe than currently accepted, and includes settlement phases in antiquity by Europeans, Southeast Asians, and Polynesians, in addition to the beringian migrations of the proto-Amerind Asians, AKA Clovis.

These settlement events have been occurring as long ago as possibly 100,000 years. What is truly amazing is that anyone seems surprised by this possibility.

I blame it on the institutionalization of that tired, worn out, construct of the "Fertile Crescent, Cradle of Civilization". One of many areas of "civilization's" development, but by no means the only one.

And we all know that humankind is nothing, if not restless and mobile.
jsa09
not rated yet Jun 30, 2010
@caliban

The Polynesians took a long to time to island hop across the pacific and would probably not have reached the Americas much before about 10,000 years ago mabe as much as 15,000 and by then the other people would have already walked down from Alaska.

Most archaeology and anthropological studies tend to agree on about the 13,000 age bracket. Although I have seen several studies reporting that there were successive waves. The successive waves were only about 1,000 years apart though and nothing like 20,000 years ago.
Caliban
3.7 / 5 (3) Jun 30, 2010
@jsa09,

I commend you to the Topper site, near Anderson, South Carolina:

http://archaeolog...pper.htm

A close reading will apprise you of a date as early as 50,000ybp. As much as 30,000years earlier than the first Asian was to have set foot upon the soil of the Americas, which we are to believe had no human inhabitants from the time of first separating from Pangaea.

While this is one of the better-documented sites, it is by no means the only, much less the oldest of the paradigm-buster sites so far uncovered in the Americas.

As I said- little mention is made of these findings, because they turn the standard model on its head, and are very difficult to reconcile with the accepted model, and are therefore largely -and quietly- ignored.

I gave you the first link- if you care to, a brief further websearch will yield many, many more.
Happy hunting, and enjoy looking at the world through new eyes!

BSW
not rated yet Jun 30, 2010
The change and huge growth of the human population is constant....but hopefully growth tapers off...before it is too late ;) dun dun dunnnnnn
Ethelred
5 / 5 (1) Jun 30, 2010
My opinion is that there will never be sufficient resolution through genome analysis to determine, authoritatively, the timeframe, much less the method of the populating of the New World.
I think the method or rather the source is more likely than the time frame.
in no way are they any longer representative of the genetic diversity that likely existed prior to first contact.
Seems reasonable for the chromosomal DNA but since the testing was for mitochondrial DNA that thinking doesn't apply anywhere near as strongly as you state. Mitochondrial DNA does NOT undergo recombination. It is strictly from the mother so if the mDNA isn't from a European than it is likely from Amerind sources. Thus it should be possible to only use mDNA that is strictly Amerind. It is likely that many lines were lost during the plagues. At least one major culture was destroyed by plague with very few survivors.

Ethelred
Skeptic_Heretic
not rated yet Jul 04, 2010
Ethel, Don't forget that in European culture the explorers were almost always men. If Men from Europe were to follow the ice sheet sans females and encounter the asiatic first inhabitants, their mDNA wouldn't have been found within the Amerind genetic history. I don't think our recursive lineage is sophisticated enough to rule out multiple population influence in the new world.
Ethelred
not rated yet Jul 05, 2010
Ethel, Don't forget that in European culture the explorers were almost always men.
True, at least for historical cases.
. If Men from Europe were to follow the ice sheet sans females
While I could be wrong on this I think that if early men were following ice sheets it would be as a tribe. The male explorers came MUCH later. Even the Vikings brought women when they came to stay. Or rather tried to stay.
I don't think our recursive lineage is sophisticated enough to rule out multiple population influence in the new world.
I don't expect it to do so. According to linguistic studies there have been at least 3 waves of immigration. The first wave that fits almost all Amerinds and apparently all Amerinds south of Mexico. A second wave that produced Pacific Northwest tribes plus the Navajo and Apache.The third wave is pretty obvious, the Inuit, and I don't think they have interbred much with main Amerind population.

Ethelred