¿Europeos pintados?
The genome of a young boy buried at Mal’ta near Lake Baikal in eastern Siberia some 24,000 years ago has turned out to hold two surprises for anthropologists.
The first is that the boy’s DNA matches that of Western Europeans, showing that during the last Ice Age people from Europe had reached farther east across Eurasia than previously supposed. Though none of the Mal’ta boy’s skin or hair survives, his genes suggest he would have had brown hair, brown eyes and freckled skin.
The second surprise is that his DNA also matches a large proportion — about 25 percent — of the DNA of living Native Americans. The first people to arrive in the Americas have long been assumed to have descended from Siberian populations related to East Asians. It now seems that they may be a mixture between the Western Europeans who had reached Siberia and an East Asian population.
The Mal’ta boy was 3 to 4 years old and was buried under a stone slab wearing an ivory diadem, a bead necklace and a bird-shaped pendant. Elsewhere at the same site about 30 Venus figurines were found of the kind produced by the Upper Paleolithic cultures of Europe. The remains were excavated by Russian archaeologists over a 20-year period ending in 1958 and stored in museums in St. Petersburg.
Together, the two genomes indicate that descendants of the modern humans who entered Europe had spread much farther east across Eurasia than had previously been assumed and occupied Siberia during an extremely cold period starting 20,000 years ago that is known as the Last Glacial Maximum.
The other surprise from the Mal’ta boy’s genome was that it matched to both Europeans and Native Americans but not to East Asians. Dr. Willerslev’s interpretation was that the ancestors of Native Americans had already separated from the East Asian population when they interbred with the people of the Mal’ta culture, and that this admixed population then crossed over the Beringian land bridge that then lay between Siberia and Alaska to become a founding population of Native Americans.
“We estimate that 14 to 38 percent of Native American ancestry may originate through gene flow from this ancient population,” he and colleagues wrote in an article published Wednesday in the journal Nature.
Dr. Willerslev thinks it more likely that European bearers of the X lineage had migrated across Siberia with the ancestors of the Mal’ta culture and joined them in their trek across the Beringian land bridge.
An unexplained feature of the mixing is that the Mal’ta people did not pass on their mitochondrial DNA since the U lineage is unknown among Native Americans. Since mitochondrial DNA is passed down only through the female line, the population ancestral to Native Americans could have been formed by men of the Mal’ta culture who acquired East Asian wives.
http://www.nature.com/nature/journal/vaop/ncurrent/full/nature12736.html
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Al parecer se ha secuenciado el ADN de un sapiens arcaico datado en 24.000 B.P. El individuo infantil está cerca del lago Baikal, otro testigo más que muestra la continuidad del gravetiense desde los Picos de Europa hasta los confines de Siberia (tradicionalmente se creía que el gravetiense era un fenómeno europeo pero hoy sabemos que llega hasta los confines de Asia). A partir del estudio de ADN se ha descubierto que el individuo infantil , que estaba enterrado aquí, tiene raíces europeas occidentales, otra pieza más que se suma junto con las Venus de Bouret a la hipótesis de la continuidad europea a lo largo de toda Eurasia.
Otro punto bastante interesante es que al parecer grupos de nativos americanos, desde Norteamérica hasta el Amazonas, presentan similitudes cromosómicas respecto al individuo encontrado en Mal´ta, lo cual refuerza la hipótesis de que algunos grupos de europeos occidentales ayudaron a colonizar el nuevo mundo. Hasta unos años se creía que la colonización asiática se llevó a cabo exclusivamente mediante migraciones asiáticas y que los que tenían rasgos de europeos occidentales no eran más que mezclas poscolombinas, posteriores al siglo XVI. El problema estaba en que muchos de esos grupos europeizantes estaban totalmente aislados de cualquier contacto con cualquier europeo y la hipótesis asiática se tambaleaba bastante. Ahora, tras la coincidencia de ADN, ya se puede asegurar que estos grupos eran individuos que llegaron a América desde el extremo occidental de Europa recorriendo la zona siberiana y atravesando el estrecho de Bering persiguiendo Mamuts hace unos veinte o treinta mil años. La influencia europea no se limitaría al ámbito cultural (Venus) si no que también sería genética.
Al final parece que no estamos tan separados como creíamos y es bien interesante. Al fin y al cabo la rama europea –blanca– se separó de la africana –negra– en el entorno del 80.000 B.P.
