The Ancient North Eurasian connection was the component that had not been clearly identified before.

It was the hidden source because it did not look like a simple East Asian contribution.

It came from a different direction, with different genetic roots, and it had been mixed and diluted and partially obscured by the later history of the founding population.

The Mal’ta boy’s genome was the key that unlocked this hidden ancestry, because it provided a reference point — a clear, relatively uncontaminated signal of what the Ancient North Eurasian population’s genome looked like — against which the mixed ancestry of later populations could be measured and analyzed.

The Peopling Of The Americas, Revisited