January 08, 2009

Concurrent but distinctive migrations into the Americas

As usual with papers such as this, it is important to note that their age estimates depend on (i) the assumption that coalescence ages of lineages correspond to migration events (in general, they do not), and (ii) the mutation rate used to estimate such ages, which may be time-dependent. In this paper:
We propose here for the first time a new mutation rate taking into account the previous estimates reported by Mishmar [35] for all coding-region base substitutions and by Kivisild [36] for only synonymous transitions. With three decimal digits used throughout, the rounded values were 5140 years per coding-region substitution and 6760 years per synonymous transition, respectively. The rho estimated (average distance of the haplotypes of a clade from the respective root) human coalescence times are then 202 kya according to Mishmar et al. [35] and 160 kya according to Kivisild et al.
The geographic patterns (Pacific coast vs. inland route) seem to be more robust than the conclusions about the supposed ages of the migrations and their temporal concurrency.

The ScienceNews reporting has some contrary views. Some related posts:
  1. Language spread rates in the Americas
  2. Earliest human occupation of southern South America
  3. Three-stage colonization model for Americas reconsidered
  4. Craniofacial shape variation and Native American origins

Current Biology doi:10.1016/j.cub.2008.11.058

Distinctive Paleo-Indian Migration Routes from Beringia Marked by Two Rare mtDNA Haplogroups

Ugo A. Perego et al.

Summary

Background

It is widely accepted that the ancestors of Native Americans arrived in the New World via Beringia approximately 10 to 30 thousand years ago (kya). However, the arrival time(s), number of expansion events, and migration routes into the Western Hemisphere remain controversial because linguistic, archaeological, and genetic evidence have not yet provided coherent answers. Notably, most of the genetic evidence has been acquired from the analysis of the common pan-American mitochondrial DNA (mtDNA) haplogroups. In this study, we have instead identified and analyzed mtDNAs belonging to two rare Native American haplogroups named D4h3 and X2a.

Results

Phylogeographic analyses at the highest level of molecular resolution (69 entire mitochondrial genomes) reveal that two almost concomitant paths of migration from Beringia led to the Paleo-Indian dispersal approximately 15–17 kya. Haplogroup D4h3 spread into the Americas along the Pacific coast, whereas X2a entered through the ice-free corridor between the Laurentide and Cordilleran ice sheets. The examination of an additional 276 entire mtDNA sequences provides similar entry times for all common Native American haplogroups, thus indicating at least a dual origin for Paleo-Indians.

Conclusions

A dual origin for the first Americans is a striking novelty from the genetic point of view, and it makes plausible a scenario positing that within a rather short period of time, there may have been several entries into the Americas from a dynamically changing Beringian source. Moreover, this implies that most probably more than one language family was carried along with the Paleo-Indians.

Link

20 comments:

  1. I hope that some scholar, who has labs and money, desire to do the same work on mtDNA N1b, which is deeply rooted in Italy and can demonstrate its expansion from here in all directions as other mrDNAs and YDnas (above all R1b1b2) did. The rare mutation of 16176 from C to G and from G to A is an important sign and can disprove the Jewish science of Mr Behar: “Hg N1b is virtually absent in Europeans” (Behar et alii, The Matrilineal Ancestry of Ashkenazi Jewry: Portrait of a recent Founder Event”, AJHG, 2006: pp. 4-5 of the paper). See: Babalini et alii, “The Population history of the Croatian linguistic minority of Molise (southern Italy): a maternal view”, EJHG, 2005: N1b in Campania 8,3%, in Abruzzo/Molise 2,7%, in Lazio 3,9%, the only 3 Italian region tested.

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  2. I understand that is becoming more and more clear that Clovis is a second wave of colonization. The last years have seen a consolidation of the pre-Clovis theory also in the archaeological field. This paper appears to ratify that.

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  3. So would the big game hunters, like mammoth, be mtDNA X2a?

    while the sea food gatherers, like fish and molluscs, would be mtDNA D4h3?

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  4. pconroy said...
    "So would the big game hunters, like mammoth, be mtDNA X2a?

    while the sea food gatherers, like fish and molluscs, would be mtDNA D4h3?"

    No. The vast majority (approx. 95% for at least native North Americans) of Native American mtDNA belongs to haplogroups A2, B2, C1(xC1a), and D1.

    Generally, it seems that haplogroup A (a subclade of N(xR)) is the most frequently occurring mtDNA haplogroup among native North Americans (especially indigenous peoples of the American arctic), whereas haplogroup D (a subclade of M) is the most frequently occurring mtDNA haplogroup among native South Americans. MtDNA haplogroup B (a subclade of R) tends to have a westerly distribution, and haplogroup C (a subclade of CZ, which is, in turn, a subclade of M) an easterly distribution, within the Americas. MtDNA haplogroup B seems to be especially frequent among natives of California, the American Southwest, Central America, and the Andes. Overall, though, I would say that the most striking regional variation in the Native American mtDNA landscape is the predominance of haplogroup A in North America in contrast with the rarity of this haplogroup in South America.

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  5. ebizur, thanks for the clarification!

    BTW, a friend of mine who is from Korea and who worked for a few years as a doctor with the Navajo people of the US SouthWest, said that they felt that he looked like one of them, and called him a word in Navajo that meant "Brother", rather then the more usual "Stranger" they apply to non-Navajo.

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  6. pconroy said...
    "ebizur, thanks for the clarification!"
    You're welcome.

    "BTW, a friend of mine who is from Korea and who worked for a few years as a doctor with the Navajo people of the US SouthWest, said that they felt that he looked like one of them, and called him a word in Navajo that meant "Brother", rather then the more usual "Stranger" they apply to non-Navajo."
    I'm sorry for asking, but what does your Korean friend have to do with this discussion about Native Americans? There is probably a residual resemblance between Koreans and Native Americans in general, especially northern Native Americans (and Navajos seem to be at least partly derived from recent populations of the northwestern part of North America), but Koreans and Native Americans have not shared any common ancestry for perhaps 10,000 years or more.

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  7. ebizur,

    That was my point!

    Most Koreans and most Native Americans are derived from a similar or the same source population - so much so that even after thousands of years, a Navajo can identify a Korean as a brother! Maybe I should have added that other Asians working on the reservation were regarded as strangers by the Navajo.

    http://www.isogg.org/ancientdna.htm

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  8. pconroy said...
    "That was my point!

    Most Koreans and most Native Americans are derived from a similar or the same source population - so much so that even after thousands of years, a Navajo can identify a Korean as a brother! Maybe I should have added that other Asians working on the reservation were regarded as strangers by the Navajo."

    Oh, all right. Thanks for the clarification.

    Well, I can understand why the Navajos might have had such an impression of your Korean friend. All I have meant to say by my previous reply is that I doubt that there should be much genetic evidence available at this point in time to support a claim that Koreans are more closely related to Navajos than Koreans are related to indigenous Americans in general, and, therefore, bringing Koreans into the discussion seems a bit off the topic of genetic diversity within the Native American metapopulation. I suppose anecdotes of that sort are not necessarily too distracting, though.

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  9. I, too, was told by the Navajo that I looked "Navajo". I'm Chinese.

    pconroy, I'm curious. What ethnicity were the other Asian scientists?

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  10. ren,

    Chinese!

    BTW, the Korean guy I know did not IMO have a typical Korean face, he had a type I've seen a few times from Korea and Northern China, where the face is longish and the bridge on the nose is of medium height.

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  11. Yes, my wife saw a picture of some Navajo soilders from WWII and she thought they were Japanese at first.

    There is overlap but it is small.

    Navajo:

    http://navajopeople.org/navajo-pictures.htm

    Koreans:

    http://tigrepelvar2.files.wordpress.com/2008/02/religion_so_koreans.jpg

    Uhm...

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  12. They don't remind me of Koreans (or whichever other East Asians) more than they can remind me of Indian or Mediterranean peoples. There are certainly peoples in America with much stronger "Mongoloid" looks (the Inuit of course but also other scattered groups, even as far south as the Amazon forest).

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  13. Maju wrote, "They don't remind me of Koreans (or whichever other East Asians) more than they can remind me of Indian or Mediterranean peoples."

    As someone who has actually travelled the Navajo reservation, seen Navajos, know what they look like, I can assure you they don't look Basque.These are what average Navajo women look like:
    http://s6.zetaboards.com/man/topic/8524962/1/

    Facial-structurally, the average Navajo is closer to Mongols in many ways the average East Asian of any country, even Korea.

    Your repeated claims that Amazon Indians look the most "Mongoloid" is also based on a misunderstanding of what "Mongoloid" means, as I've repeated explained. It would be like equating "Caucasoid" with European, when northern Europeans and southern East Asians tend to devaite from the strict "Mongoloid", "Caucasoid" definition.

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  14. I can assure you they don't look Basque.

    I fully agree with that. Don't worry.

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  15. But they remind you of Basques,hehe..
    And that's because you still haven't bothered to look..

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  16. But they remind you of Basques,hehe..

    No. Not at all. I said Indians and maybe even Mediterraneans (and thinking in people of Iran and North Africa rather than anything else - you know that my very uncoonian concept of "Mediterranean" does not refer so much to Mediterranean Europe but rather to the other side of the sea and the apparent influences on this side from that origin: in general people who's quite tanned even in winter and with an indoors profession - but let's not open a discussion on what "Mediterranean" may mean)

    The pics posted by Dragon Horse look somewhat Gypsy/Indian (specially young people), not really "Mongol". The ones posted by you suggested me more Philippines than anything else but some can be percieved as similar to NE Asians too (even if with darker pygmentation in all cases).

    And yes, I did look, silly.

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  17. They don't look Filipino, for obvious reasons that perhaps you don't notice. I hesitate to explain.

    Anyway, Native Americans who look "Med" to you, to me look more like certain types of East Asians:
    http://s6.zetaboards.com/man/single/?p=8002843&t=8524316

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  18. ren,

    Interesting images of "Yi" people - that's exactly the kind of look I meant earlier, when I said some Northern Chinese and Koreans - now I have the name for it - thanks!

    Cheers,
    Paul

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  19. Your welcome, pconroy. I'm glad and surprised that you were still keeping tabs on this thread.

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  20. Your welcome, pconroy. I'm glad and surprised that you were still keeping tabs on this thread.

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