I still recall a book on Atlantis which (among the dozen or so avenues of inquiry) showed the remarkable similarity of common word roots among the existing cultures on all land masses ringing the Atlantic in early history. Just that one effort, with the amazing number of identical (or nearly so) words/meanings, was enough to convince me that, not only had there been extensive interrelations among all these peoples, but that they all likely had a common origin - the diaspora of Atlantean refugees.