Grounded on solid evidence- fossil bones and tools whose ages could be generally agreed upon, man had not arrived in America until well after the end of the last ice age, when the great ice sheets that once blanketed much of North America had disappeared and many of the animals contemporary with them had become extinct.
The discovery that began breaking down the official view of man's postglacial sea voyage to America was made by a man whose name almost never appears in texts of American archeology. The McJunkin - Figgins discovery of the Folsom bison hunters established man's arrival in the New World in the ice age.
A land bridge existed then between Asia and Alaska. It had never appeared when the glaciers of the last ice age were at their peak, locking up in the ice millions of cubic miles of precipitation that would normally have gone into the Ocean. The absence of this water lowered the level of the Bering sea more than 300 feet, enough to turn the shallows of the Bering Strait into a bridge of land connecting the two continents. Folsom culture began nearly 11000 years ago and Clovis a thousand years or earlier. To reach mid-continent by that time, men must have crossed to Alaska no later than about 15000 years ago-about the time that last ice age was ending and the land bridge was being submerged. New discoveries and reassessments of old ones kept pushing the date of man's arrival in America further back in time. And every change in date raised new questions about haw he came.
Artifacts that my be crude stone scrapers and choppers found at Lewisville, Texas, and other scattered sites throughout North and South America have been dated by their surroundings as early as 25000 to 35000 years ago. Thus, strange as it seems, some of the very first huntsmen to reach our own evolutionary level apparently braved the rigours of the ice age Arctic to migrate from Siberia to Alaska and wander south into the center of the continent - all within a few thousand years.
