The ancient DNA evidence has consistently shown that much of what looks like adaptation was actually migration: the people who look adapted to an environment often arrived there from elsewhere, with characteristics they had evolved in a different environment.

Third, genetic characteristics are not fixed properties of geographic populations.

The people of a geographic region change — through migration, through selection, through the random processes of genetic drift — in ways that make any attempt to define an “original” or “authentic” genetic type for a region fundamentally misguided.

Cheddar Man illustrates all three of these insights: he experienced rapid evolutionary change in his line (light skin evolution after his death, presumably including some selection on his descendants’ line), he was part of a migrating population that had brought its characteristics from elsewhere, and the characteristics of his geographic region have changed substantially from his time to the present.

Why The Story Is Not Simple