They were not simply passing through.

Their genetics told a story that no one could read for six thousand years.

The specific molecular record of their ancestry — the particular pattern of genetic variants that distinguished their lineage from every other South American population studied so far — waited in the dense bone of their inner ears through the rise and fall of every civilization that followed them on the same plateau.

The Herrera-period people who came two or four thousand years later did not carry their genetic signature.