This component was not large enough or clear enough, in the analyses of modern genomes alone, to clearly identify its source.

It appeared as a residual — something left over when the East Asian signal was accounted for, something that required explanation but that had no obvious source population in the modern world.

The MA-1 genome provided that source population — or at least its best ancient representative.

The people of the Mal’ta region in Siberia, around 24,000 years ago, carried genetic ancestry that was specifically related to the residual, non-East-Asian component in modern Native American genomes.

They were not themselves the founding population of the Americas — they were too far geographically from the route into the Americas, and too early in the timeline, to have walked directly into the Western Hemisphere.