Ancient DNA: Muddy messages about American migration.

Abstract

When and by which paths did early humans migrate into America? An analysis of ancient plant and animal remains revises the timeframe during which a route may have opened between ice sheets in northwest America. See Article p.45 During much of the last ice age, continental ice sheets prevented humans from migrating into North America from Beringia, the area between Siberia and what is now the Bering Strait. At some point, a route opened up between the Cordilleran and Laurentide ice sheets, but it is thought that this 1,500-kilometre-long ice-free corridor may have been too cold to act as a human migration route. Eske Willerslev and colleagues present a series of environmental reconstructions based on coring of lake sediments in what was once the ice-free corridor. Their data indicate that the corridor would have still been inhospitable even after humans are known to have arrived in the Americas south of the ice. This implies that humans migrated by a coastal route, now submerged by the risen sea.