Yep, it used to be career suicide to go against the Clovis First theory. It was settled science and enforced much the same way that AGW is enforced today. I love holding up Clovis First as an example of how settled science often is not and how a group of scientists in a field can intimidate peers from putting forth competing theories despite growing evidence that their pet theory could be wrong.
Isolationism — which is popular with some people even here on FR — is and was a political view, and was the root cause of the widespread popularity of Alex Hrdlicka’s relentless attacks upon the idea of precolumbian contact. The fact is, he was an overbearing a-hole.
It’s also a fact that he picked off a lot of low-hanging fruit(cakes) who claimed that this or that culture in the Americas *had to be* related to some better-known Old World culture.
It’s also a fact that there was contact, and lots of it, unrelated to each other for the most part, and that Columbus went to Iceland to find out about the lands to the west. IOW, to say that either one was all correct and the other was all incorrect is an unsupportable position to take.
Career suicide, yes, because all the tenured old guys had built careers on their theories and were making a bundle of money requiring their own books as college texts. It's an old saw that new theoretical work can't proceed until the previous generation of theorists is dead and gone. Unfortunately the "new generation" usually can't wait to assume the perks and privileges of the old one. They'll fight just as hard to suppress any ideas that conflict with their own.
This is a problem of human nature and institutional corruption that has nothing to do with the validity of the scientific method as Dr. Thorne implied.