Anthropology

are considering is a water route along the southern shore of the land bridge, Beringia between Asia and North America. Once in North America, they would have traveled along the Pacific coast of North America, on to Central and South America.

This makes a lot of sense if they were from a maritime oriented culture. One objection is that the land bridge was not completely exposed long ago enough to allow people to get to South America 25,000 to 30,000 years ago by following the southern coast of Beringia. But, the land bridge of Beringia did not form overnight. During its formation over several decades or longer, large parts of it would have been exposed as islands surrounded by shallow water.

There were already islands from western Alaska almost to northeastern Asia, before the land bridge developed. Those islands are visible today on a map. Early modern humans were eating fish, shellfish, and seaweed along continental coasts as they left Africa. As long ago as 50,000 years ago people were traveling in boats and reached Australia. So a maritime oriented culture in northeastern Asia could have island hopped between Asia and North America before the full Beringian land bridge surfaced. As more land was exposed, the islands would have grown larger and therefore, closer together. People could have traveled down the Pacific coast of North America without ever knowing that they had entered another continent.

We don't have much evidence of older dates in North America because the exposed land on the coast of North America got submerged when sea levels rose again. So our oldest dates are in South America so far since people could follow the coast that far and would probably have done that if they were from a maritime culture.