The track record of pre-Clovis claims, through the middle of the twentieth century and into the later decades, was not encouraging.

By 2008, however, the Clovis-first model was already under pressure from multiple directions.

Monte Verde in southern Chile — a site with compelling evidence for human presence approximately 14,500 years ago, verified by independent researchers — had by then been accepted as a genuine pre-Clovis site by most specialists, though some holdouts remained.

The geographic argument was damning: if people were at the southern tip of South America 14,500 years ago, they must have entered the Americas before that — probably well before — to have had time to travel that far from the entry point in Beringia.

The Clovis-first model had been weakening for years before Paisley was published.