 |
|
High-tech undersea search for the first Americans
Ocean archeologist Robert Ballard is searching the floor of the Gulf of Mexico, via remote control.
from the March 14, 2007 edition
Page 2 of 4
Dwellers on an ancient coast
An abundant amount of salt left from an even earlier time when a closed-off Gulf of Mexico completely evaporated would have provided an invaluable resource for preserving meat. Salt licks also would have attracted grazing animals and potential game. Inhabitants would have also found the coastal estuary full of easily harvestable shellfish, and if they ate shellfish, they probably left behind large piles of discarded shells that scientists can radiocarbon date. Because of the continental shelf's gradual incline in the area, rising seas would have quickly inundated the land, increasing the chances that artifacts were preserved.
This is Ballard's high-tech quest: proof of human habitation in the Gulf. That might refute the classic hypothesis that the first humans in the Americas were Siberian hunters, who followed herds over the Bering land bridge some 11,500 years ago. The hunters, the theory goes, passed into the interior of the continent via an ice-free corridor on the east side of the Canadian Rockies. Archaeologists call them the Clovis culture, after a distinctive spear point found near Clovis, N.M., in the 1930s.
But in the past 20 years, archaeologists have excavated many sites with radiocarbon dates older than the Clovis culture. Tools and shelters at Monte Verde in Chile are 12,500 years old. Stone flakes and fire pits found at the Meadowcroft Rockshelter in Pennsylvania date to 14,000 years ago – before the corridor to the interior would have been open. This observation gave birth to an alternate hypothesis: Perhaps the first Americans skirted the glaciers in boats.
An ice-free corridor inland
Bolstering this possibility, scientists now think that a sliver of coast between the great Cordilleran glacier on the Canadian Rockies and the Pacific Ocean remained clear during the Ice Age.
In 1997, Daryl Fedje of the Canadian Parks service pulled up a stone tool from the seafloor 170 feet down. The tool could have fallen there, but the seafloor itself, which was dotted with tree stumps and littered with pine cones, was clear evidence of an inhabitable ice age forest along the coast. Early seafarers could have occasionally pulled up to land during their migration.
But nothing has complicated the picture more than genetic evidence. Studies of native American groups indicate that up to five waves of people arrived at different times. Four of them – A, B, C, and D – are related to populations in Asia. Several of these groups share genetic markers with people in modern-day Indonesia, Australia, and the Pacific Islands – places scientists think were settled by seafaring people.
Further confusing the picture, this fifth group, called "X," also shares genetic markers with European populations. Although controversial, this evidence lends credence to another, stranger possibility: Stone Age Europeans sailed west and made landfall in what was, even then, a land of immigrants.
RSS feed