Because of parsimony, evidence for one theory is also evidence against another. We have a patchy record of debitage and ancient DNA stretching from Siberia acro

Because of parsimony, evidence for one theory is also evidence against another. We have a patchy record of debitage and ancient DNA stretching from Siberia across Beringia and down into continental North America. We can actually directly map the broad spread of humans out of Africa and around the world with things like the serial founder effect, and it points to a migration around the Pacific rim contributing most of indigenous ancestry. None of this completely rules out alternative hypotheses (and indeed you can't), but it's evidence against them and suggests that they're either unlikely or insignificant.