[HamiltonJay]

Given the fact the land bridge is mostly underwater, finding out one site is younger than believed doesn't rule out its existence or use... the "land bridge" was huge... not saying they didn't come in boats... but this hardly discredits the land bridge theory in and of itself.

[SauronOfMordor]

Given that the Australian aborigines settled there around 50K BC, what's the big deal about assuming people from Siberia managed to cross over to Alaska at a fairly early time?

[RightWhale]

the land bridge is mostly underwater

Even now the local residents go way out on the ice hunting. You can still cross from Alaska to Siberia on foot if you go on the ice, and it's not an easy trip, although you need permits. Another thing is why it would take 1000 years to go from top to bottom of the Americas. If somebody wanted to he could have walked all the way in a few months.