SMBE 2014: Genome-wide ancestry patterns in Easter Islanders suggest a pre-European admixture event with Native Americans

Genome-wide ancestry patterns in Easter Islanders suggest a pre-European admixture event with Native Americans
José-Víctor Moreno-Mayar* 1, Andaine Seguin-Orlando*1, Morten Rasmussen1, Erik Thorsby2, Simon Rasmussen3, Eske Willerslev1, Anna-Sapfo Malaspinas1
1Centre for GeoGenetics. University of Copenhagen, Copenhagen, Denmark, 2Institute of Immunology. Oslo University Hospital. University of Oslo, Oslo, Norway, 3Center for Biological Sequence Analysis. Technical University of Denmark, Kongens Lyngby, Denmark
Easter Island (Rapanui) in Polynesia is one of the most isolated places in the world inhabited by humans. Archaeological and genetic evidence point to a first colonization by Polynesians from the West around 1200 AD. The possibility of an admixture event with Native Americans, before the island was discovered by Europeans in 1722, has been raised due to archaeological and single locus genetic evidence. This evidence, although suggestive of a potential contact, remains inconclusive. In this study we investigate whether such an event happened by generating genome-wide data from Easter Islanders.

We have generated genome-wide data for 10 unrelated reputedly non-admixed Easter Islanders. By using non-parametric multidimensional statistics and clustering methods, we show genome-wide patterns consistent with both Native American and European admixture. We infer local Polynesian, Native American and European ancestry tracts and compare their length distributions to those expected under different demographic history models. We find more support for a model with Native American admixture event that predates a European admixture event. By masking the European and Native American ancestry tracts, we reconstruct the recent history of the Easter Island population compared to other existing genotyped Oceanic populations. These results provide additional detailed insight into the demographic history of Polynesian islanders revealing an outstanding event in recent human history.
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5 comments:

  1. Steve SailerJune 9, 2014 at 11:54 PM

    Score one for Thor Heyerdahl?

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  2. patrickJune 10, 2014 at 2:42 AM

    Traces of Native American ancestry (mtDNA) have been found in some Icelandic families, so it's hardly a surprise. We know the Polynesians reached the Americas (on at least one and probably multiple occasions) and brought back sweet potatoes, why couldn't they have brought back women as well?

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  3. AnonymousJune 15, 2014 at 2:51 AM

    "Traces of Native American ancestry (mtDNA) have been found in some Icelandic families, so it's hardly a surprise."

    Is this really true? Were they inuit? I always thought that Iceland was incredibly homogenous. Even if it was just a few families, could it in any way explain the looks of Bjork? Though small in number, she's not the only remarkably mongoloid Icelander I've seen.

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  4. patrickJune 19, 2014 at 5:20 AM

    It is. Haplogroup C1e which is a rare variant of Haplogroup C (almost nonexistent outside of the Americas and East Asia.) It is a few families with a common ancestry.
    http://news.discovery.com/history/us-history/vikings-native-american-woman.htm
    They may have been Inuit or more likely Tuniit or Beothuk (groups that are now extinct)

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  5. n/aJune 20, 2014 at 6:47 AM

    Patrick,

    C1e is not Amerindian.

    The authors' own analysis shows that the coalescence of C1e with Amerindian C1 lineages predates the settlement of the Americas, and no C1e mtDNA has ever been reported in Amerindians -- despite the fact that large numbers of Amerindian mtDNA have been sequenced (especially in relation to the relatively small number of founder lineages).

    C mtDNA lineages are also found in Europe at low frequencies. A published German example is mentioned in the paper which is a perfect HVR I match for the Icelandic C1e. The authors acknowledge "an Asian or European origin cannot be ruled out", while bizarrely calling this possibility "unlikely" (when in fact the existing data tends to rule out an Amerindian origin). If they had been responsible, they would have gotten ahold of and fully sequenced the German sample, but apparently they were afraid that might have prevented them from getting some headlines.

    C1 mtDNA has also been found in mesolithic European individuals.



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