To understand why the Manis site was so controversial, and why confirming or denying its age mattered so much, requires a brief account of why the Clovis-first model had come to dominate American archaeology for so long.

The Clovis people — or more precisely, the people who made the distinctive fluted stone projectile points first identified near Clovis, New Mexico, in the 1930s — were not named for a specific cultural identity or ethnic group.

The name came from the site where their most characteristic stone tools were first found in clear association with the bones of extinct Pleistocene animals.

Clovis points are unmistakable: large, beautifully made bifacial tools, thinned to dangerous fragility by the removal of a longitudinal channel — the flute — from the base on both faces.