I normally have a soft spot for unconventional models of
American prehistory. Boas's speculations about the Iroquois
representing a northward back migration from South America always
fascinated me as did his idea that Raven myths found there way from
North America to Siberia. In contrast the thinking behind the
Solutreah hypothesis strikes even me as unimpressive.
It helps that Boas had some observations to go on!
Hrdlicka impresses me, how he traveled around to investigate claims of Pleistocene man in the Americas. That's the spirit I like -- take the claims seriously, go there and investigate, and report whether the evidence is good or not. We have too much arm waving today.