Settling America by Sea?

The big game hunters called Clovis people--whose ancestors crossed the Bering land bridge and swept southward through the Americas perhaps 11,200 years ago--have long been considered the first Americans. But now two independent teams working in Chile report in tomorrow's Science the first hard evidence for a shadowy alternative: that the first Americans arrived by boat, leaving few traces of their journey.

The theory of coastal exploration has been hard to verify, because most of the clues left by ancient coastal explorers would now be underwater, drowned some 10,000 years ago by sea levels rising after the last ice age. Along the southern coast of Peru, however, the sea floor slopes steeply away from the coast. As a result, "very little land horizontally was lost to rising sea level," says archaeologist Daniel Sandweiss of the University of Maine, Orono. "This is one of the reasons I was looking for sites in this region," he says.

The hunch paid off: His U.S.-Peruvian team found an ancient maritime campsite that is 11,100 years old (Quebrada Jaguay). Then David Keefer of the U.S. Geological Survey in Menlo Park, California, and his colleagues found a similar site dating to 10,700 years (Quebrada Tacahuay). So intently did these people focus on the ocean that 99.8% of the bones at the older site belong to marine creatures, such as anchovies and seabirds. At both sites the teams found remains of small, calorie-rich fish, indicating an early net fishery--a very specialized maritime occupation, notes Keefer.

Both the early dates and the maritime lifestyle make it unlikely that these people were the descendants of land-lubbing Clovis people, says Anna Roosevelt, an archaeologist at the University of Illinois, Chicago. Even researchers who have searched for the earliest South Americans in highland sites are now giving the maritime idea serious consideration. "I've long pushed the idea of people moving down the flanks of the mountain zone," says archaeologist Tom Lynch, director of the Brazo Valley Natural History Museum in Bryan, Texas. "But it may be that people actually came along the coastal fringe."