Firstly the Eskimos probably didnt have quite such fancy kayaks eighteen thousand years ago.

Secondly though, if you're struggling to survive in a vast empty landscape already you don't have a lot of time or motivation for ten thousand mile voyages of exploration.

Travel a hundred miles and you're really tired and you're in a different part of Alaska where you don't know where the good food and water sources are.

Keep travelling yet further and eventually you reach a place where you don't even know what food sources look like.