But, in response to recent discoveries of what seem to be older human artifacts in South America, the archaeology profession has prematurely jettisoned this theory for an alternative view based on theoretical sea travel, says Temple University anthropology professor Anthony Ranere.
"Mine is a somewhat unpopular position, but I think the bulk of the evidence still supports the late entry, fast movement model," says Ranere. "According to the model that I prefer, people first crossed the Bering Strait Land Bridge into North America about 12,000 years ago."
However, older artifacts thought to date to 12,500 years ago have been found in Monte Verde, Chile. How could archaeologists explain these finds? By proposing that ancient travelers boated down the North American West Coast 25,000 or more years ago. "They could hardly have left Alaska any other way during the period from 25,000 to 12,000 years ago since a massive continental ice cap covered the entire upper half of North America, forming a barrier to overland movement," says Ranere.
But Ranere points out that many other sites, once thought to be much older than the 12,000 years before present entry date, have been discredited one by one due to errors in dating. Only Monte Verde stands unchallenged. "If some flaw in the dating of Monte Verde is eventually discovered, which leads to a revision of its antiquity to say, 10,500 years before present, then the late entry model again makes sense," says Ranere.
Ranere argues that, given the amount of game available, once on the North American continent, bands of hunters would have been able to move rapidly into new and strange areas without having to wait generations to gain intimate knowledge of the plants in different climates. "Spear points are not root grubbing tools, they're for killing game, and no specialized plant processing tools have yet to be identified in these early sites," adds Ranere.
Ranere's own painstaking field work at La Mula-West along the central Pacific coast of Panama backs up his claims. He has recovered spear points manufactured with the same technology as early spear points from North America.
"La Mula-West is essentially a workshop for manufacturing stone tools. In order to gear up for hunting, ancient people had to stop near sources of jasper, flint, obsidian, or other suitable rock types, and make large numbers of spear points. Since many points were broken in the manufacturing process, a large amount of workshop debris is left behind for us to analyze. So, if a lot of time had elapsed between occupation of sites in North America and our site in Panama, you would expect to see an evolution of technology, instead of the identical technology we found," says Ranere.
The spear points could be quite deadly weapons. "There is some evidence that ancient people used an additional section of wood called a spear thrower to extend the length of their arms, allowing them to really hurl these spears 70 to 80 meters with some accuracy," notes Ranere.
Ranere will take seven students along when he returns to central Panama this summer. This time, he is looking for remains of early crops that early hunters and gatherers added to their diet between 8,000 and 9,000 years ago.
Ranere presented his views in April at the meeting of the Society of American Archaeology in Nashville.