This is one of the most significant gaps in the current understanding of early American genomic history, and filling it — if sites preserving ancient DNA from the relevant period can be identified — would substantially advance the field.

Route And Timing — What Is Still Debated

The specific route or routes by which the founding population of the Americas reached the hemisphere from northeastern Asia remains one of the most actively debated questions in the study of early Americans.

The USR1 genome contributes to this debate but does not resolve it.

Two main routes have been proposed and debated for decades.

The first is the interior route — movement through the ice-free corridor that opened between the Laurentide and Cordilleran ice sheets as they retreated during the end of the Ice Age.