If the Ancient Beringian lineage went entirely extinct — if the people who represented this distinct early American branch died out without any descendants — then USR1’s genome is the only direct evidence of their existence.

If they were absorbed through admixture, then their genetic legacy is distributed, in diluted form, among the descendants of the populations that mixed with them.

Current evidence cannot definitively distinguish between these possibilities, and subsequent ancient DNA studies from Alaska and adjacent areas will be important in characterizing what happened to the Ancient Beringian lineage in the millennia after USR1 lived.

What can be said is that the Ancient Beringian lineage was real, was distinct, and persisted long enough — at least until 11,500 years ago — to be preserved in the genome of a child buried in the interior of Alaska.