The skepticism was not irrational.

The history of paleoanthropology and Paleoindian archaeology was littered with spectacular claims that had not survived the scrutiny they deserved.

Responsible scientists understood that the burden of proof for a genuinely extraordinary finding had to be correspondingly high — and that the specific case for pre-Clovis human presence in the Americas had to meet that burden before it could be accepted.

The dominant model during the period when Gustafson was excavating the Manis site was still, in its broad outlines, the Clovis-first hypothesis.