A Single Main Migration Across Bering Strait?

The web is abuzz over a new publication in PLoS Genetics about a single main migration across Bering Strait. From what I can tell, this new paper, “Genetic Variation and Population Structure,” coincides with a recent publication in PLoS One that sampled mtDNA and figured out people moved in waves, but first they spent some time in Beringia.

The Populations Sampled in the Genetic Comparison of Native AmericansBoth of these papers use microsattelites or SNPs in genes from native American populations to answer the question, did a small population from Siberia trek across the Bering Strait land bridge some 12,000 years ago and give rise to the native peoples of North and South America? Or did people come from other parts of Asia or Polynesia, arriving in multiple times, at several places on the two continents, by sea as well as by land, in successive migrations that began as early as 30,000 years ago?

To answer this question, the authors picked out 678 markers in the DNA of present-day members of 29 Native American populations across North, Central and South America. They also analyzed data from two Siberian groups. The figure to your right is from the publication, which illustrates who and where the populations sampled are from.

They figured out that a unique genetic variant, which is part of a noncoding region, is widespread in Native Americans across both American continents and it originated in Siberia. This implies that the first populations came into the Americas came from a single migration or multiple waves from a single source. This rules out the possibility that people came in waves of migrations from different sources. The following graph documents this:

Siberia is the closest match

Furthermore, the genetic diversity, as well as genetic similarity is very close to the Siberian groups tested. This supplements to existing archaeological and genetic evidence that the ancestors of native North and South Americans came by the northwest route.

Additional findings that are also interesting are that populations in the Andes and Central America are genetically similar. And populations from western South America showed more genetic variation than populations from eastern South America. And to appease the linguists out there, the populations more similar linguistically were also more similar genetically. Pretty cool, huh?

Anyways, please check out Blaine Bettinger, a.k.a, the Genetic Genealogist’s and Yann‘s posts on this, as well as my old post about the waves from Beringia, which collaborates with this finding.

18 thoughts on “A Single Main Migration Across Bering Strait?

  1. Frankly, this is awesome. However, I would warn readers that our picture is still incomplete for several reasons.

    I am not sure where the samples are coming from, and I trust that they are balanced and numerous, but we know historically that Pre-Columbian populations experienced massive population reductions at the time of European Contact. Taking that into consideration, as well as the assumption that warfare and genocide are tendencies of human behavior over time, how much human genetic history is lost? Is there anyway to sample Pre-Columbian human remains, or did the studies consider that? Would that change the outcome of the study?

    And were an Amazonian peoples sampled?

    I also found interesting that Andean populations and Central American populations are similar.

  2. neoteotihuacan, this image from the publication documents what populations were sampled.

    You bring up a very astute point about native populations. They were much larger prior to the 1500’s than they are currently, which coulda supported a much different genetic diversity. I guess the ultimate conclusion that can be drawn from this current analysis is that current populations are related to a Siberian ancestral population. But we kinda already knew that, other genetic studies have supported this. The archaeology indicates this. And the skeletal morphology does so as well.

    The only thing that this study effectively does is write off the genetic contributions of Polynesians to American populations when they brought chickens to south American, which was questioned earlier this year.

    Anyways, excellent comment. Thanks for catching that and taking the time to write about it.

    Kambiz

  3. neoteotihuacan’s points are well taken. Loss of DNA lineages through time is possible and may not be represented in the current data. Likewise, ancientDNA, especially from South Paleoamerindians, may change or solidify our interpretations. Nonetheless, this is a comprehensive study that makes sound connections of archaeology, genetics, and linguistics.

    The cranial morphology of certain South American Paleoamerindian samples resembles Australesians more than certain North American samples. Why? The authors of these studies (Neves et al) still favor the Beringial multi-migration hypothesis, with a rapid initial migration to South American accounting for such similarities and a later migration accounting for the derived morphology. This is perhaps where ancientDNA might shed some light? But otherwise, let’s be careful in completely dismissing the possibility of trans-oceanic genetic contributions to South American populations. It may not be the case for extant populations, but for extinct ones for which we have skeletal remains? The great majority of the evidence points to the former beringial scienario, but we still have gaps nonetheless.

  4. There are unquestionably major differences, morphological and cultural, between certain South and Central American populations and others in other parts of the Americas, especially north of Mexico, where the homogeneity is much greater. Linguistically there is much greater diversity in Central and South America. And, according to certain other research, the greatest genetic diversity seems to be in S. America, not N. America. Many South American groups look very different from North Americans, in many cases much more like Melanesians.

    My own specialty is music and I can tell you there are huge differences between America north of Mexico, where, with only a few exceptions, you have essentially three instrument types, the membranophone, the rattle and the flute. In Central and South America there are far more different instrument types, not only among the more “advanced” cultures, but even among hunter-gatherers or simple horticulturalists. And here too the resemblances to Melanesia are striking, including the use of pipes, both panpipes and free pipes and also trumpets. All these instruments are played in ensembles using a technique common in Africa, SE Asia, Indonesia and Melanesia (but almost absent in N. America) called “hocketing,” and they are very often divided into male-female pairs, as in Africa, SE Asia, Indonesia, China and Melanesia.

    I’m not suggesting trans-Pacific migrations, there is no evidence of that at all. But there IS good evidence for a very early migration beginning in SE Asia and continuing along the East coast of Asia to the coast of Beringia and then down the West coast of the Americas. This would have been an extension of the original coastal Out of Africa migration. The most logical explanation of the total American picture is the one offered by Steven Oppenheimer in his book “The Real Eve.” For a summary, you can check his interactive map, the “Journey of Mankind”: http://www.bradshawfoundation.com/journey/

  5. Victor. Nice link. As far as I’m aware there is no actual evidence that humans moved along the coast through India, just that it’s the most obvious route to have been used. But there are many problems with the idea, not least being that any moving group of humans would rapidly suffer inbreeding depression. I’ve been able to put comments on this subject at:

    http://remotecentral.blogspot.com/2007/11/human-evolution-on-trial-hybrid-vigour.html

    You may like to comment. There is also the problem that Y-chromosome and mitochondrial DNA evidence doesn’t support that migration route either. Australian Aborigine and Indian lines are very different. Sure, it’s possible to argue any original Indian lines died out. But it’s my understanding the modern humans reached Sri Lanka long after they’d crossed Wallaces line to reach Australia and New Guinea. Doesn’t fit the pattern shown in the link.

    The link also says the first modern humans out of Africa became extinct. In fact mtDNA evidence can be interpreted as indicating they didn’t. Human mtDNA lines are much older than Y-chromosome lines.

    All this of course has very little to do with America.

  6. What you’ve written on inbreeding is very interesting and defintely worth considering. I’m assuming there’ve been studies done on the effects of inbreeding on animals. Do you know of any results? Is it possible to develop a viable lineage from only one breeding pair?

    In the Out of Africa case, it seems to me that the problem you’re considering would be relevant if the original OOA migrants were all from the same family. If several different families were involved, then the dangers of inbreeding would be greatly reduced, no? The same would be the case with population bottlenecks I would think.

    IMO, Out-of-Africa should really be called: Out of Africa with Bottleneck(s). That’s what makes Oppenheimer’s thinking on all this so convincing — he takes the bottleneck issue very seriously, whereas many others gloss over it. There ARE significant differences that need to be taken into account in any version of OOA. In other words, for OOA to have real explanatory value, it would seem that some sort of major bottleneck, via either Toba or a Tsunami, perhaps, is almost a necessity for OOA to work.

    As far as the differences between mtDNA and Y lines, I don’t see your point. Both lines take us back to Africa but neither supports the survival of the earliest Out of Africa migration, into the Levant. I don’t understand the technicalities well enough to explain why, but I don’t know of many geneticists who believe that line survived.

  7. Victor asked, “Is it possible to develop a viable lineage from only one breeding pair?” In practice extremely unlikely. If the pair had no disadvantageous genes then yes it would be possible. But animal breeders have found this situation to be so rare as you might as well say it doesn’t exist.

    I agree various groups of humans have been through several bottlenecks. But not necessarily the whole human population at once. However I would argue that many people have an emotional desire to believe we all come from just one small group. After all two thousand years of Western history has been based on the idea.

    I’ve been meaning to mention that I too have noticed surprising similarities between some SE Asian Music and some African. But we have to remember that Madagascar was settled by what we today would call Indonesians. Presumably they reached the African mainland and took their music and instruments, especially xylophone types.

  8. Terry, the Out of Africa migration itself is evidence of a bottleneck affecting the lineage of everyone without exclusively African roots. And if there were no other major bottleneck after this migration, as produced by the Toba explosion or some other major disaster, it would be very difficult to explain the morphological, genetic and cultural differences and patterns we find in the world today.

    The Out of Africa evidence is very real and very convincing, not at all the product of wishful thinking. Whether all homo sapiens derive from a single “Adam and Eve”-like pair is highly debatable, agreed. But the mtDNA of everyone tested so far has pointed quite clearly to a single female progenitor, in Africa. She was not the only “modern” human alive at that time, but she was, apparently, the only female whose lineage has survived to the present day. The evidence for her existence is very strong.

  9. TerryT:

    “I’ve been meaning to mention that I too have noticed surprising similarities between some SE Asian Music and some African. But we have to remember that Madagascar was settled by what we today would call Indonesians. Presumably they reached the African mainland and took their music and instruments, especially xylophone types.”

    Thanks for raising that very interesting point. You might be familiar with the work of A. M. Jones, who did very detailed comparative studies of African and Indonesian xylophones, finding several remarkable points of similarity. He too postulated an influence from Indonesia through Madagascar to Africa. The problem with this theory is that it is not borne out by the distribution of xylphones in Africa, which are, I believe, more common in the West than the East — and not common in Madagascar itself.

    A more recent and more convincing interpretation (as offered by, among others, Roger Blench) is that the commonalities could be due to the presence of African slaves in Southeast Asia and/or Indonesia at some point in the distant past. The xylphone could have diffused in this area in a manner very similar to the way the marimba became so popular in Latin America as a result of the influx of African slaves in the colonial era.

    While I have found strong evidence of an “African signature” in SE Asia and Indonesia and Melanesia dating possibly to the “Out of Africa” migration, I see no evidence that xylophones were part of that very early development.

  10. Victor: it is “very difficult to explain the morphological, genetic and cultural differences and patterns we find in the world today” through an out of Africa hypothesis. However it is extremely easy to explain through a spread origin hypothesis. The fact that all humans alive today share a single female and single male ancestor tells us absolutely nothing about what other genes survive. Both lines have moved independently through the geographic range of the human species.

    An early expansion through India seems a necessary assumption for the out of Africa hypothesis to stand. But where’s the evidence? For example I was just looking at Wikipedia:

    http://en.wikipedia.org/wiki/Haplogroup_C_(Y-DNA)

    From the article: “It represents a great coastal migration along Southern Asia, into Southeast Asia and Australia, and up the Asian coast.” Note, no ‘maybes’ or ‘possiblys’. But when we read more closely: “Haplogroup C5 occurs at a very low frequency in India, Nepal, and Pakistan.” Note, not in southern tribal groups which is what we’d expect if C5 was an early arrival and SE Asian types derived from types who had moved through India. Also: “Haplogroup C3-M217 is probably the most important of these, as the geographic extent of its dispersal is without compare”. Across the northern latitudes from Germany to North America. Now isn’t that what we’d expect if Y-chromosome C had moved through Central Asia?

    I’ve said before that many people seem to have an emotional need to accept a single point of origin for all species.

    I realise that Xylophones tend to be most common in West Africa. That has occurred to me in the past.

  11. One thing that bothers me (if I’m not missing something) is that neither Athabascans nor Inuit seem to have been sampled. If this is so, then it’s not at all clear that there was a single migration, for the Athabascans and Inuit are the ones usually hypothesized to be most distinct. This is particularly relevant considering the recent (and now widely accepted) view that the Athabascan and Yeniseian languages form a single family. Thus only the Athabascans and Inuit speak languages that are part of families that occur both in Asia and America.

    1. I’m just an 83-year-old grandma who recently got my cheek swab gene story from the Genome Project. My ancestors took the Sinai split of L3 to western Asia where that group got so mixed up the National Geographic is developing some new strategies to straighten the confusion out. It doesn’t take much imagination to see that the next bus stop could lead to Bering Strait. I await updates with bated breath.

      The distinctness you mention, of Athabascan and Inuit genetic groups, has also been suggested to be the result of a really large single migration over long periods of time. Like central Asians and coastal Asians moving across the Strait, the coastals moving south and the Athabascan Centrals spreading East through the North American inlands in similar time periods. The language similarities are really interesting. I’d like a reliable source for some of this early history.

      50 years ago I took two quarters of a class called Transpacific Contacts by Professor Alex Krieger who was the then supervisor for all the University of Washington digs south of the Mexican Border. I saw hundreds of slides of early Mexican and Central American pottery and statues, etc. paired with nearly identical versions from such places as the Valley of Kashmir, China, and Japan (9000 year old vase). The Kashmir item was a strange boat known only in Kashmir and from Teotihuacan. both boats were used for a unique form of agriculture known only to those two places, but the Mexican boat was 1000 years later than the Kashmir boat.

      Krieger also told of a Chinese Emperor who was having the history of the world written by eminent authorities of the time. He sent 5 monks to travel across the Pacific to get the history of the natives of Central Am. and Mexico (Aztecs and related natives. They took a hairless dog with them, and there are hairless dogs to this day in Mexico.

      We saw more slides and evidence of the monks’ arrival and an extended stay along the North coast of South America. I think the Chinese history book got burned later so we didn’t find out if the monks ever got back home. Krieger never finished his book on Transpacific Contacts, and probably lost his battle for the concept because the transpacific contact thing was in the process of being drummed out of the U of W archeology department. However, the cultural evidence for east-west contacts was huge, and as I learned at a young age, archeology is riddled with politics.

      On another note, the large number of Inuit and Athabascan tribes in N. America plus their still incomplete genetic history suggests the movement of one large migration, or two crossings of Bering Strait of the same migration, coming from Siberia and Mongolia, and possibly other Asian areas, at much earlier dates than the 5 monks story, certainly suggest connections with the Asian continent.

      My thought at the time, and still is, that both theories need to be considered as complementary events rather than having two camps arguing the topic. There was trans pacific navigation earlier than we first thought.

      Hey, we may be talking about me, and my Inuit son-in-law, so I’m interested in all theories!

      Virginia

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