The hypothesis was partly driven by physical similarity between northeastern Asian and some North American Indigenous populations that early observers noted, and partly by the logical requirement that people had to have gotten here somehow.

In the nineteenth and early twentieth centuries, American anthropologists and archaeologists developed increasingly systematic approaches to the question, while also operating within the racial and cultural assumptions of their era — assumptions that often led them to underestimate the antiquity and complexity of Indigenous cultures.

The search for evidence of an American Paleolithic — a stone tool culture comparable to the ancient stone tool traditions of Europe — was shaped by those assumptions in ways that sometimes led researchers to reject genuine evidence of great antiquity because it did not fit the expected pattern.

The discovery of Clovis technology and its association with extinct Ice Age animals in the 1930s provided what seemed like a clean answer to the question of earliest Americans: the Clovis people, arriving approximately 13,000 years ago, were the first.

The answer was accepted with varying degrees of enthusiasm, but it held the field for several decades, partly because it was supported by genuine evidence and partly because it was simpler than the alternatives.

The gradual erosion of the Clovis-first consensus was not a dramatic overthrow but a slow accumulation of evidence that the model could not accommodate.