Agreed, up to a point. The spread of a "Clovis Culture," from either the west or the east, would have taken much longer than called for in such theories. Ergo, it had to be a "clovis technology" that spread so quickly by being shared among cultures already in place. And the discovery of occupation sites much older than the allowed 11,500 - 13,000 YBP confirms this. To consider the possibility of an independent evolution of human beings in the Americas, however, boggles the mind. Surely the current model is simpler and more likely, if we push the dates back - WAY back to the point it could SEEM that some indigenous cultures have "always been here." The Tlingit, on the other hand, tell stories of how they migrated from the Mediterranean areas across the Atlantic to the eastern American seacoast, then found their way to the extreme northwest by land and sea. So: Siberian Bridge, Atlantic crossing, "always been here" -- likely there's a good deal of truth in all of them, when we give up the idea we have to choose just one.