Secondly, I think that land-bridge theory is a real diaper-load of misinformation.
Skulls of euro-trash have been found predating most of my red skinned cousins. Just because some of my more misguided Northwestern U.S. cousins wanted to claim those lost bones doesn't make them right. Get over it! They (first euro-trash): came, made no difference, did not survive, and did not propagate. So what?
The truth be told, CHINESE seafarers more than likely traded with my cousins on the West Coast long before Jesus was nailed to the tree.
And that land-bridge theory? Total arrogance.
Who is truly informed enough to say my distant ancestors (and maybe yours) didn't PADDLE or SAIL across the Bering Strait, or walk across the ice? There is no evidence of a LAND bridge.
Mr. Churchill, is that you???
In theory, Beringia actually was a "land bridge" because massive glaciers (which are made of ice) cause sea levels to drop.
But you're right, the Aboriginal Americans could have travelled by boat as well as by foot, just as the people living there now do.
I dunno, myself.
Barry Fell pretty much convinced me that there was even some commerce across the Atlantic in the millenium BC.