For much of the 20th century, scientists believed that the first settlers of the Americas could only have arrived one way. As the conventional story went, an ice-free super highway opened up across the Bering Land Bridge toward the end of the last ice age, allowing people from Eurasia to follow big game like bison and mammoths down through the interior of North America.
That's always been a dumb idea to anyone who actually does follow game - So they're chasing mammoths and bison across the ice flows for months, eh? Tell me then, what are the mammoths and bison EATING up there on the ice?
All there was for people to eat along there were seals and fish, and maybe whales and walruses. That's seagoing boats drifting the front edge of the ice, if anything at all.