Supposedly, based on a handful of similarly-shaped stones (understandably deemed to be arrowheads or spear points), scientists have “determined” that American Indians (for lack of a better term) migrated from Asia, across the Bering Strait land bridge and then south through the “ice-free corridor”.
What I find funny is there is no compelling, geological proof that there was an ice-free corridor. It is supposed that during the last ice age the Cordilleran and Laurentian ice sheets had withdrawn to such an extent as to leave a large corridor across the plains free of ice, making it easy and tempting for Paleoindians to migrate south. As I said, there’s no compelling, geological evidence that such a corridor existed, so there’s not necessarily any really tempting reason for Paleoindians to migrate south.
Plus, that ice-free corridor would have been accessible about 15,000 years ago, but there’s compelling archæological evidence that there were humans living in South America almost 20,000 years ago. Not surprisingly, most archæologists who believe in the land bridge theory completely dismiss the theories about South American populations prior to the end of the last ice age.
But assuming a common rate of cultural evolution among European/Mediterranean and American people, it is hard to imagine complex civilizations like the Toltec, Olmec, Inka, Maya and Aztec/Mexica arising from migrant hunter-gatherer populations within 10,000 years.
Anyway, there’s still a lot that is not known and not proven, so I’m always skeptical when I read about evidence to support the land bridge theory. Food for thought.