November 17, 2010

mtDNA haplogroup C1 in Icelanders: a genetic mystery

American Journal of Physical Anthropology DOI: 10.1002/ajpa.21419

A new subclade of mtDNA haplogroup C1 found in icelanders: Evidence of pre-columbian contact?

Sigríður Sunna Ebenesersdóttir et al.

Although most mtDNA lineages observed in contemporary Icelanders can be traced to neighboring populations in the British Isles and Scandinavia, one may have a more distant origin. This lineage belongs to haplogroup C1, one of a handful that was involved in the settlement of the Americas around 14,000 years ago. Contrary to an initial assumption that this lineage was a recent arrival, preliminary genealogical analyses revealed that the C1 lineage was present in the Icelandic mtDNA pool at least 300 years ago. This raised the intriguing possibility that the Icelandic C1 lineage could be traced to Viking voyages to the Americas that commenced in the 10th century. In an attempt to shed further light on the entry date of the C1 lineage into the Icelandic mtDNA pool and its geographical origin, we used the deCODE Genetics genealogical database to identify additional matrilineal ancestors that carry the C1 lineage and then sequenced the complete mtDNA genome of 11 contemporary C1 carriers from four different matrilines. Our results indicate a latest possible arrival date in Iceland of just prior to 1700 and a likely arrival date centuries earlier. Most surprisingly, we demonstrate that the Icelandic C1 lineage does not belong to any of the four known Native American (C1b, C1c, and C1d) or Asian (C1a) subclades of haplogroup C1. Rather, it is presently the only known member of a new subclade, C1e. While a Native American origin seems most likely for C1e, an Asian or European origin cannot be ruled out.

17 comments:

Joshua Lipson said...

Finally, Bjork explained.

waggg said...

Related to the Y-DNA hg Q in Iceland, Faroe and Norway?

German Dziebel said...

I commented on this one on Razib's Discover blog: http://blogs.discovermagazine.com/gnxp/2010/11/icelanders-descended-from-native-americans/comment-page-1/#comment-50822

Andrew Oh-Willeke said...

Wow!

Given the evidence that there were multiple layers of pre-Columbian population replacement known to have taken place in Artic North America, the notion that there might have been an mtDNA haplogroup C1e in Greenland in the 10th century that is now extinct, outside of Iceland isn't implausible.

The article is behind a paywall so it is hard to tell how many Icelanders this involves.

If there are just four women with this trait in 1700 in Iceland, give or take a few, another possible source would be early post-Columbian contact at sea with the Americas, for example with individuals who joined crews or were brought hoome as wives following port calls in connection with the whaling trade, perhaps from North American tribes that were basically extinguished early in the early colonization process on Northeast North America. You really need to be able to trace at least one of the matrilines back another two hundred years to be very definitive about a pre-Columbian source.

One could also, I suspect, infer a minimum expected percentage of C1e from a single woman's descendants based on the population of Iceland in 1000 CE v. 1600 CE as a hypothesis test to see if either possibility is ruled out or strongly favored over the other.

If there were an Asian source, you would expect some sort of trace appearances of mtDNA C1e somewhere in the expanse all across Arctic Eurasia or Atlantic Europe by now, so that seems considerably less likely as a source.

Andrew Oh-Willeke said...

Earlier related research using the same database shows that:

"The vast majority of contemporary females (58,832 or 91.7%) are descended from only 22% (7,041) of the potential matrilineal ancestors born between 1848 and 1892, and most contemporary males (57,686 or 86.2%) are descended from only 26% (8,275) of the potential patrilineal ancestors. The results are even more striking for matrilines and patrilines traced back to the 1698–1742 ancestor cohort. Because of the decay of genealogical information as we go further back in time, a greater proportion of the contemporary cohort could not be successfully traced back to ancestors. However, 62% (39,615) of contemporary females are descended from only 6.6% (1,356) of the potential matrilineal ancestors born between 1698–1742 and 71% (47,335) of contemporary males are descended from only 10.3% (1,859) of the potential patrilineal ancestors. The higher percentage of patrilineal links to the 1698–1742 ancestor cohort results from a more comprehensive recording of paternity in early Icelandic historical sources (a consequence of male bias in most historical documents)."

The Y-DNA Q data are restated here, and don't necessarily point to a North American link, although key Y-DNA markers on this score were not tested. There is also indication in the literature that some Y-DNA R1 types are actually Q but not detected since the test wasn't capable of resolving the two different Y-DNA types.

Crimson Guard said...

I thought they settled the question years ago:

http://www.cbc.ca/news/story/2003/10/28/inuit_blond031028.html

Icelanders are a mix of Briton and Norse:

http://decodeyou.com/2009/01/stories-from-our-foremothers-decode-publishes-an-unparalleled-genetic-snapshot-of-iceland-1000-years-ago/#more-561

http://dienekes.blogspot.com/2009/06/regional-population-structure-in.html


... with some Aboriginal Inuit from around that circum polar area, so really whats the big mystery?

n/a said...

In the literature the authors find 76 complete C1 sequences: 72 Amerindian, four Asian, and zero European. The Icelandic C1 belongs to a different subclade than all of the previously-published sequences. Amazingly, the authors conclude that since "three of the four previously characterized C1 subclades are" Amerindian, Icelandic C1 is probably also Amerindian in origin. Needless to say, the much more reasonable assumption is that Icelandic C1 came from Europe.

Creative said...

Vikings brought Roma mtdna to Britain via romantic love or something, maybe this one to.

A Romani mitochondrial haplotype in England 500 years before their recorded arrival in
Britain.

The most likely explanations are that either the historical record is wrong, or that early liaisons between Norse and Romani people during their coincident presence
in ninth to tenth century Byzantium led to the spread of the haplotype to England.


http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1617141/

German Dziebel said...

"with some Aboriginal Inuit from around that circum polar area, so really whats the big mystery?"

All Inuits, including those in Greenland, belong to either A or D mtDNA haplogroups http://onlinelibrary.wiley.com/doi/10.1002/ajpa.20313/abstract. Hence, they can't be the source of C1 in Iceland. At least not according to the data.

"If there were an Asian source, you would expect some sort of trace appearances of mtDNA C1e somewhere in the expanse all across Arctic Eurasia or Atlantic Europe by now, so that seems considerably less likely as a source."

Tamm et al. (http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0000829) reported the westward movement of C1a and A2a into Siberia from North America and Beringia.

Overall, lineages related to Amerindian ones aren't the most frequent even in Siberia. In South Siberia, A, B, C and D are found in the same population at frequencies less than 5%. Eurasia has been swayed by large-scale population movements post-LGM, and the lineages belonging to the original foraging populations are likely to have been reduced to naught in many places. (Think of Y-DNA D in Andamanese, Tibetans, Thai and Ainu but hardly anywhere else in (South)East Asia). With better sampling and aDNA studies we have a greater chance of finding more of those. C1e in Icelanders very well may be that kind of Pleistocene retention driven to higher frequencies in a northern refugium. This is exactly what we find with mtDNA X, which is detected at elevated frequencies on an island in Scotland, in Georgia (the mountainous refugium) and in self-induced Druze refugium in the Middle East. Then it suddenly re-appears in North America, with little to no traces in Northeast Asia.

pconroy said...

German,

If it's true that there is only A or D found in Inuits today, then that makes this much more interesting!

Now I think you may be right, it may actually be a Paleolithic survivor from Northern Europe.

Andrew Oh-Willeke said...

"Eurasia has been swayed by large-scale population movements post-LGM, and the lineages belonging to the original foraging populations are likely to have been reduced to naught in many places. (Think of Y-DNA D in Andamanese, Tibetans, Thai and Ainu but hardly anywhere else in (South)East Asia). With better sampling and aDNA studies we have a greater chance of finding more of those. C1e in Icelanders very well may be that kind of Pleistocene retention driven to higher frequencies in a northern refugium. This is exactly what we find with mtDNA X, which is detected at elevated frequencies on an island in Scotland, in Georgia (the mountainous refugium) and in self-induced Druze refugium in the Middle East. Then it suddenly re-appears in North America, with little to no traces in Northeast Asia."

The trouble with that theory is that Iceland's current population dates from 847 CE onward, and has had two episodes of New World contact (Leif Erikson era and post-Columbian to 1700 CE) that predate the oldest established presence of C1e in Iceland, but very little contact with Asia in that time period. The large scale population movements that happened in Eurasia had already happened by then. Yet, you don't find a single example of C1e anywhere in the British Isles or Scandinavia which are the predominant source populations for Iceland. There is one example in Germany, and one in the Canary Islands, both of which can be easily explained as having a New World or Icelandic source.

eurologist said...

"Now I think you may be right, it may actually be a Paleolithic survivor from Northern Europe."

Perhaps the same as with the Q that I mentioned in the other thread: the periglacial Ahrensburg/Hamburg people, who incidentally seem to have brought the first truly effective bows and arrows to Europe (given the sharp increase in clearly identifiable arrowheads).

German Dziebel said...

"If it's true that there is only A or D found in Inuits today..."

To the best of my knowledge, yes, but we may need to call Ebizur out to have it verified.

terryt said...

"All Inuits, including those in Greenland, belong to either A or D mtDNA haplogroups"

But C is certainly found further south on the mainland. And we know the Vikings established a presence, although probably breif, on the mainland. So any American women reaching Iceland need not have come from Greenland. Interesting that the same C does not survive in America today but we also know there was a severe bottleneck in the Native American population, especialyy along the eastern seaboard.

German Dziebel said...

"Perhaps the same as with the Q that I mentioned in the other thread: the periglacial Ahrensburg/Hamburg people"

Archaeology is useless here, unless remains are directly sampled. But as far as Y-DNA Q is concerned - yes - it does sound right. Also, mtDNA D5 and Z1 in Saami should be mentioned, a layer preceding their post-LGM U5 lineage.

Kepler said...

This may give some hints:

Vikings in America

Unknown said...

Just wondering the freq of C1 in Northern Asian populations? And if it could have been present in Saami populations? Not that I don't think it came from a 'new world' source, I was just wondering.