The genome of a young boy buried at Mal'ta, near Lake Baikal in eastern Siberia, about 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.
The second surprise is that his DNA also matches a large proportion - about 25 per cent - 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 remains were examined by a team led by Eske Willerslev of the University of Copenhagen. Dr Willerslev, an expert in analysing ancient DNA, was seeking to understand the peopling of the Americas by searching for possible source populations in Siberia. He extracted DNA from bone taken from the child's upper arm, hoping to find ancestry in the East Asian peoples from whom Native Americans are known to be descended.
But the team was amazed when the nuclear genome also showed part-European ancestry.
He said his finding did not solve the much-disputed question of when the Americas were first settled. Archaeologists long believed the people of the Clovis culture, dating from 13,000 years ago, were the first Americans, but several recent finds point to an earlier date.
''We need the sequencing of more ancient genomes to address this question,'' Dr Willerslev said.