The Last Giant of Beringia: The Mystery of the Bering Land Bridge
Marschall, Laurence A., Natural History
The Last Giant of Beringia: The Mystery of the Bering Land Bridge by Dan O'Neill Westview Press, 2004; $26.00
The idea that a landmass once joined America and Asia arose not long after the explorer Vasco Nuñez de Balboa, in 1513, first waded into the ocean that separates the two continents. In 1590 José de Acosta, a member of the Jesuit brotherhood, published a natural history of the New World that drew on biblical "facts" to prove the existence of such a bridge. Native Americans, he wrote, being descendants of Adam and Eve, must have migrated on foot from the environs of the Garden of Eden eastward to the mountains of Mexico and Peru. Fray de Acosta reasoned that they must have come across a land connection somewhere in northwestern North America. That coastline, however, would remain uncharted for more than a century, until its exploration by the Scandinavian navigator Vitus Bering.
By the middle of the twentieth century, the conjectured existence of a Bering land bridge had been bolstered by a wide range of circumstantial evidence. New World animal species that live along the shores of the Arctic Ocean appeared to be similar to the Old World species that inhabit Siberia. And the farther south you went, the greater were the differences between the species on the opposite shores. The evidence suggested that a wave of animal migrations radiated southward from the Arctic long ago; as time passed and the distance from their common origin increased, the Asian species diverged from their North American counterparts.
Oceanographic data provided another line of evidence. A continuous continental shelf fringing Asia and North America was discovered offshore. Geologic records suggested that sea levels during the last ice age were low enough to expose the shelf beneath what is now the Bering Strait, between Alaska and Siberia. But "land bridge" seems an inexact term for a connection that, unlike the narrow isthmus that joins North and South America, was probably, at its widest, as broad as the north-south distance across present-day Alaska. For that reason, specialists prefer to call the connection Beringia, reflecting its former character as a shared territory, a cosmopolitan province where the mammoths and steppe grasses of the Old World mingled with those of the New. …