Another genetic puzzle has been the fact that most modern Europeans have certain DNA sequences that are similar to those of some American Indians but different from those of most Asians, including natives of Siberia. How can this be, since American Indians are supposedly descended from Asians who migrated across the Bering land bridge from Siberia to Alaska about 14,000 years ago? Were there ancient seafarers in the Atlantic? Or is it simply from mating between European settlers and American Indians after Columbus? Neither, as it happens.

Modern DNA could not resolve these issues, but ancient DNA provides answers. Eske Willerslev’s research group at the University of Copenhagen, working with Russian scientists, read the genomes of two bits of human remains found near Lake Baikal in Siberia; one of these individuals lived 24,000 years ago, the other 17,000.

Both had genes similar to modern Europeans and modern American Indians but distinct from modern Siberians or other East Asians. As the researchers say in a paper published early last year in Nature, this implies that a population of hunter-gatherers lived in northern Eurasia in the last ice age and partly gave rise to the first Americans in the East and to Europeans in the West, before they themselves died out in Siberia and were replaced by immigrants from elsewhere in Asia.

This may help to explain the enigma known as Kennewick Man, a 9,000-year-old skeleton from Washington state, which seems to have features more like those of a modern European than of a modern American Indian. The earliest inhabitants of the Americas seem to have been distant cousins of Europeans, connected through Siberia, with their genes later diluted by other Asians migrating through Alaska.

As this example shows, one of the common themes of research on ancient DNA is that the mixing of native and immigrant populations happened much more often than previously suspected. The new research allows us to identify the many different elements of that complex history. It is like watching a cake being reverse-engineered into flour, sugar, eggs, milk and its other ingredients. The familiar textbook notion that, for most of human existence, people native to one region developed in isolation from those native to a different region no longer makes sense.

bbauska wrote:
(Just kidding, and have fun with this...)