The Altai Mountains in northern Asia, where Mongolia meets Siberia, have proven to be a treasure trove of preserved ancient human DNA. The cold and arid conditions mean that DNA can be sequenced from human remains that are thousands of years old. It was in this region that scientists found evidence of a new human species, the Denisovans, in 2010. Sequencing the DNA of many individuals from this region also make clear that it was a kind of crossroads for travelers from many cultures who left their mark by bearing descendants.
The migrations of humans from Asia into North America gave us Native Americans beginning 20,000 to 30,000 years ago. But genetic evidence from Siberia now shows that the migrations went the other way as well. Long after Native American DNA became distinct from earlier Asians, it showed up again in Asia. Three individuals who died around 500 years ago show significant DNA from Native Americans. Geneticists estimate that their American ancestors probably crossed back over around 5,000 years ago. The land bridge across the Bering Strait was gone by then, but they could have crossed by boat. Read about the new genetic discoveries in ancient human lineages that tell stories of human migrations at Smithsonian.
(Image credit: Nadezhda F. Stepanova)