That picture shows an Americas populated by the descendants of a founding population that entered from Beringia, spread rapidly southward, and then began to diversify rapidly as different groups adapted to radically different environments — the Arctic tundra, the Pacific coast, the Great Basin, the tropical forests, the high Andes, the Patagonian plains.

The diversification was rapid in genomic terms and corresponded, in the archaeological record, to the development of the many distinct regional technological traditions that followed the Clovis horizon.

The Anzick child was present at the moment when that diversification was beginning.

His genome preserves the signature of a population that had not yet fully separated into the many distinct peoples of the Americas that would follow.

He is, in that specific sense, among the last of a relatively undivided founding population — or more precisely, the representative of a population that was at an early stage of the differentiation that would eventually produce the enormous diversity of the hemisphere’s Indigenous peoples.