Today science does not have all the answers to the anthropological problem which arose when Balboa discovered the Pacific and Magellan crossed it, thus dropping the world’s largest ocean in between the Americas and the Garden of Eden. So far as early man is concerned, we know a good deal about how he came, and whence, and a little about when.
Except for the passionate protagonists of Atlantis and of its “opposite number,” the mythical land of Mu lost in the depths of the Pacific, most students agree that early man came across what is now Bering Strait—not by way of the Aleutians, for their inhospitable western tip is separated from Asia by 225 miles of sea with one small island midway between. For a long time, the Bering Strait route was supported only by a priori reasoning, but of late years the weapons of early man have been found either alone or with the fossils of extinct mammals in parts of Alaska and north-west Canada.
Bering Strait—Freeway to the New World
Though early man from northern Asia certainly crossed in one area and in one area only, he may have made the crossing by any one of three methods. That depends on when he came.
If he came rather late—say around 10,000 years ago—he had to negotiate Bering Strait, open water in summer, iced over in winter. If the migrants were a boating and fishing people voyaging north along the Asiatic shore, the 56-mile gap of Bering Strait, broken by the Diomede Islands, was a negligible barrier, since the greatest stretch of open water was only 23 miles across. If they found the strait frozen over, they would have followed the southern edge of the ice. Men of a more inland type, men less given to water travel, could have crossed to Alaska—as some do now—on the ice of winter.
If early man first came to the New World in the Great Ice Age or in the time when the glaciers were beginning to melt, he could have crossed dry-shod on a land-bridge. Geologists have calculated that the water withdrawn from the ocean to form the glaciers—which were half a mile to two miles thick over much of Canada and the northern portion of the United States—would have lowered the water level in the Bering Strait region by as much as 200 to 300 feet toward the end of the Great Ice Age.[7] In addition, the ocean floor of the strait—relieved of so much weight of water—would doubtless have risen to some extent. Since, at present, portions of the strait reaching from shore to shore are not more than 120 feet deep, a land-bridge is a perfectly plausible hypothesis. Of course the bridge would have disappeared with the end of the glaciers, which means that, if man had to come over dry-shod in the summer, he must have invaded America while the glaciers were still fairly extensive.
THE LAND-BRIDGE TO THE NEW WORLD
A conservative map of shorelines during the last glaciation, based on a drop in sea level of 180 feet. Geologists believe that the ice impounded in the great glaciers and ice fields of the world lowered the ocean 200 to 300 feet. The southern shore of Alaska during the last glaciation may have been much nearer its present position. (After Johnston, 1933.)
