[NukeMan]

"I don't see this at all. That's a diffusion rate of around 10 miles per year. Even non-nomadic people can achieve that"

Ever since I have been old enough to understand the meaning of the Bering Strait migration theory, I have turned over this very same question in my mind. There just doesn't seem to be enough information to answer it dispositively. 10 miles/year surely doesn't sound so tough, but why do it at all? And why was the migration primarily South vice Easterly expansion? We may never know because we cannot think like they did, and the motivation for a 'rapid' 10 miles/year (if indeed that is what it was) is forever beyond us. Frustrating.

[SauronOfMordor]

And why was the migration primarily South vice Easterly expansion?

If they were fishers, they would have followed the coast southward