When researchers examined the genetic distances between USR1 and the various ancient and modern Native American genomes available for comparison, they found that she was more distantly related to all of them than those populations were to each other.

In population genetic terminology, she was basal to the sampled Native American populations.

This means that in the family tree of Native American populations — the branching diagram that shows how different groups relate to each other and to their common ancestors — USR1 sat closer to the root of the tree than any previously sampled population.

She belonged to a lineage that diverged from the ancestors of other Native American populations before those populations began to differentiate from each other.

The researchers who published the 2018 Nature paper on USR1 — Moreno-Mayar and colleagues — described the lineage she represented as Ancient Beringians.