Whether humans crossed the seas between the Old World and the New in the times before Columbus is a tantalizing question that has long excited scholarly interest and tempted imaginations the world over. From the myths of Atlantis and Mu to the more credible, perhaps, but hardly less romantic tales of Viking ships and Buddhist missionaries, people have speculated upon what is, after all, not simply a question of contact, but of the nature and growth of civilization itself.

To the specialist, it is an important question indeed. If people in the Western Hemisphere and in the Eastern...