Hem > Antropologi > Indianerna härstammar både från européer och asiater

Indianerna härstammar både från européer och asiater

november 24, 2013

Amerikas indianer härstammar från både européer och indianer. Det står klart efter att forskare har sekvenserat hela genomet från en fyraårig pojke som dog för 24 000 år sedan i Mal’ta i södra Sibirien. Generna avslöjar att pojken förmodligen var brunhårig, brunögd och hade fräknar. I graven fanns bland annat en figurin, som var vanlig i Europa under istiden.

DNA visade släktskap med européer och indianer men inte med asiater. Mellan 14 och 38 procent av indianernas gener beräknas komma från den sibiriska gruppen.

Y-DNA tillhör haplogrupp R, vilken idag är mycket vanlig i Europa, och ganska vanlig hos Nordamerikas indianer. mtDNA tillhör haplogrupp U, vilken de första moderna människorna i Europa hade. Idag är den haplogruppen ovanlig i Europa. Bland indianerna förekommer A, B, C, D och X, men inte U.

DNA från en vuxen man som dog för 17 000 år sedan i samma område visade också på europeisk tillhörighet.

Resultatet kan förklara varför den 9000-årige Kennewick-mannen har europeiska drag.

Upper Palaeolithic Siberian genome reveals dual ancestry of Native Americans

Maanasa Raghavan, Pontus Skoglund et al.

The origins of the First Americans remain contentious. Although Native Americans seem to be genetically most closely related to east Asians1, 2, 3, there is no consensus with regard to which specific Old World populations they are closest to4, 5, 6, 7, 8. Here we sequence the draft genome of an approximately 24,000-year-old individual (MA-1), from Mal’ta in south-central Siberia9, to an average depth of 1×. To our knowledge this is the oldest anatomically modern human genome reported to date. The MA-1 mitochondrial genome belongs to haplogroup U, which has also been found at high frequency among Upper Palaeolithic and Mesolithic European hunter-gatherers10, 11, 12, and the Y chromosome of MA-1 is basal to modern-day western Eurasians and near the root of most Native American lineages5. Similarly, we find autosomal evidence that MA-1 is basal to modern-day western Eurasians and genetically closely related to modern-day Native Americans, with no close affinity to east Asians. This suggests that populations related to contemporary western Eurasians had a more north-easterly distribution 24,000 years ago than commonly thought. Furthermore, we estimate that 14 to 38% of Native American ancestry may originate through gene flow from this ancient population. This is likely to have occurred after the divergence of Native American ancestors from east Asian ancestors, but before the diversification of Native American populations in the New World. Gene flow from the MA-1 lineage into Native American ancestors could explain why several crania from the First Americans have been reported as bearing morphological characteristics that do not resemble those of east Asians2, 13. Sequencing of another south-central Siberian, Afontova Gora-2 dating to approximately 17,000 years ago14, revealed similar autosomal genetic signatures as MA-1, suggesting that the region was continuously occupied by humans throughout the Last Glacial Maximum. Our findings reveal that western Eurasian genetic signatures in modern-day Native Americans derive not only from post-Columbian admixture, as commonly thought, but also from a mixed ancestry of the First Americans.

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