By roughly 9,000 years before present, what researchers call the “southern Native American” lineage — the one associated with Anzick-1 and related individuals — had become the dominant ancestral source for populations across South America.

The ancient genomes from the Andes, from Amazonia, from the southern cone of the continent, largely reflect this common ancestry, with variations reflecting the specific population histories of different regions.

Into this framework, the Checua individuals introduced an unexpected complication.

The seven Preceramic hunter-gatherers from Checua showed no affinity to the Anzick-1 genome — that is, they did not carry the ancestry associated with the Clovis-related founding lineage.

This was not entirely surprising, since other ancient South American populations also show reduced affinity to Anzick-1, instead being connected to different aspects of the founding radiation.