It is thought now that modern humans arrived in the Americas as early as 14,500 years ago. However, I have not been able to find out when these modern humans would have ceased intermingling with the Asiatic people across the Pacific. Would it be as soon as the Bering land bridge ceased to exist? Or would it have been much more recent than that?

To add on this I have a tie in question. I have heard that all humans likely have a Most Recent Common Ancestor as early as 5,000-10,000 ya. However, if humans ceased to mingle between North America and Asia then how could this be? Would this suggest that all current descendants of the Native Americans have mixed heritage with Europeans and Africans that arrived after 1492? I suppose nearly 500 years makes this not too unlikely of an answer.