LDSFAQS, Nightlion, and any other science deniers who may be reading this:
If you look at Dr. Southerton's graphic in my post above, you will see that the pre-Columbian New World genome is represented in green, indicating that it is different and distinguishable from all of those shown in the Old World.
This came about because of more than 10,000 years of reproductive isolation from these Old World lineages. The pre-Columbian New World genome derives from four Old World lineages or clades with several subclades. While the pre-Columbian New World lineages represent the same haplogroups as the Old World lineages from which they descended, the New World populations are genetically distinct.
Best evidence now suggests that there was a 10,000 to 15,000 year "hold up" in migration during which these ancestors of the New World Native Americans were reproductively isolated, either in Siberia or Beringia, before they were able to move on in to North America and expand south and east.
During the 10,000 to 15,000 year reproductive isolation, they developed a distinct set of mutations or genetic markers in their mitochondrial DNA (mtDNA; which is inherited only from the mother).
Humans acquire and accumulate non-lethal mutations at a fairly constant and well understaood rate. It turns out, therefore, that DNA analysis, especially mtDNA and Y-DNA, mapping, can yield not only information about the approximate time that a mutation was acquired, but given the slow migrations of humans in ancient times, it is also possible to get an idea of where mutations were acquired, as well as where (and approximately when) the descendants that carried that mutation expanded.
The pre-Columbian New World genome indicated in Dr. Southerton's graph is shown as distinct from Old World DNAs. The article I cited earlier reports high resolution mtDNA analysis that shows these early migrations (comprised of the four lineages or clades and their subclades) were foundational for
all of the mtDNA found in the pre-Columbian New World.
While there are slight variations in estimates as to how long ago the Beringia migration started and when it ended, there is complete consensus among mainstream scientists, based on genetics and archeology, that there were simply no trans-oceanic contributions to the pre-Columbian New World genome - period.
Without having a clue what he is talking about, ldsfaqs will no doubt invoke "genetic drift" and then say that we could never detect a contribution to the pre-Columbian genome represented by mere 20 people in the Lehite group after all this time.
If I told ldsfaqs that Neanderthal DNA that was inserted into the European genome some 38,000 year ago by a limited interbreeding was detectable today, he would find some apologetic excuse why this evidence is irrelevant.
If I told him that the descendants of single Amerindian woman brought to Iceland from North America, who bore a single child more than 1,000 years ago, could be identified today in Iceland and Northern Europe, he would probably say that this proves nothing.
In fact, both of these examples (and many others) show that genetic markers in mtDNA can be very persistent. In fact, as I am sure some folks know, it has been possible for population geneticists to identify and date mitochondrial "Eve" - an ancient female (our most common matrilineal ancestor) who has contributed to the mtDNA of every living human on the Earth today.
Mark Stoneking was one of the authors of the paper in Nature that first reported this result from a massive worldwide genetic mapping effort in 1987. His then-wife did a lot of the statistics work on the project in the early going. I know something about this because she and I have co-authored papers togther and in the course of our projects we have had long conversations about how this work was done. It was a truly massive effort (and may have cost Stoneking his marriage). In any case, there is a NOVA program about this work that features an interview with Dr. Stoneking. It is well worth watching.
While some of the details have been adjusted since 1987, the existence of the mitochondrial Eve and of a mitochondrial DNA "clock" is now accepted science. Some of the methods for using the "mitochondrial clock" that Stoneking and his colleagues (including his then-wife) developed during this work have helped to nail down and verify the dates of the Beringia migration that gave rise to the pre-Columbian New World genome.
The message from all of this to the TBMs is that you cannot possibly claim to be a rational thinker and still deny this science. As with evolution itself, this is another case where you clearly have to choose between science and religion - between rational thinking and irrational superstition.
ETA:
New Scientist Here is what I said, NL:
Best evidence now suggests that there was a 10,000 to 15,000 year "hold up" in migration during which these ancestors of the New World Native Americans were reproductively isolated, either in Siberia or Beringia, before they were able to move on in to North America and expand south and east.
Here is how the original authors stated this conclusion:
Or, to express this first conclusion another way, the ancestors of Native Americans who first left Siberia for greener pastures perhaps as much as 30,000 years ago, came to a standstill on Beringia – a landmass that existed during the last glacial maximum that extended from Northeastern Siberia to Western Alaska, including the Bering land bridge – and they were isolated there long enough – as much as 15,000 years – to maturate and differentiate themselves genetically from their Asian sisters.
If you disagree with these conclusions, as stated by me or by the original authors, then you are taking a position that is diametrically opposed to science, which is, of course, your right.