Sea's Bounty, Not the Mammoth, May Have Drawn Nomads to Alaska
By JOHN NOBLE WILFORD
Published: December 26, 1989
A PREHISTORIC tableau is etched in the popular mind. On a bleak plain, hunters wrapped in animal skins and carrying spears lean into the frigid wind as they pursue the caribou and woolly mammoth; women and children follow them. These are the first migrants crossing from Asia to North America many thousands of years ago over the connecting bridge of land where the Bering Strait is now.
''That image is almost certainly all wrong,'' said Dr. William W. Fitzhugh, an anthropologist and director of Arctic research at the Smithsonian Institution.
New interpretations of archeological and geological discoveries have led some scientists to conclude that many, if not all, of the first Americans were not primarily big-game hunters but a maritime people. They presumably came across in the last Ice Age, sometime between 25,000 and 12,000 years ago, when much of Europe, Siberia and northern North America were covered by great masses of ice. With so much water locked up in ice, sea levels plunged more than 300 feet, exposing the sea floor between Siberia and Alaska and creating a dry connecting plain at least 1,000 miles wide.
The migrants did not cross the interior tundra of some narrow land bridge, according to the emerging hypothesis, but followed by foot or perhaps with skin boats the more hospitable southern coast of the exposed land mass that extended south in the present Bering Sea, at times as far as the Aleutian Island chain. Along this coast, they lived on the more plentiful supply of fish, sea mammals and birds.
''To some degree we're speculating,'' Dr. Fitzhugh said. ''But the data we are getting is moving us away from the hunters-on-the-tundra scenario.''
Studies of fossilized pollen show that the land bridge interior was so bitterly cold then that vegetation was probably too sparse to attract enough caribou and other large animals to have supported migrant hunters. No stone weapons or other human artifacts have been found in the North American Arctic that can be definitely associated with bones from mammoth kills. Soviet excavations in Asia indicate that the early people there were not necessarily nomadic hunters; most of their preserved weapons and art suggest they hunted small game like rabbits.
Moreover, archeologists are turning up increasing evidence that people who lived on the American coasts of the Bering Sea and Pacific Ocean 6,000 to 8,000 years ago had relatively advanced maritime cultures. They made fish hooks and harpoons of bone and hunted whales, which meant they must have had boats. Archeologists say the complexity of these societies indicates that they descended from people with a much more ancient maritime tradition, complete with a boat-building technology.
''The resources of the coasts have been almost totally overlooked in studies of early man in America,'' said Dr. William S. Laughlin, an anthropologist at the University of Connecticut in Storrs and one of the earliest proponents of the maritime hypothesis.
Dr. Knut R. Fladmark, professor of archeology at Simon Fraser University in Burnaby, British Columbia, conceded that most experts remained committed to the idea of the first migrants being big-game hunters crossing the dry interior of the land bridge.
''Archeologists by the nature of their business look to the land instead of the sea,'' Dr. Fladmark said. To substantiate the coastal scenario, archeologists would have to go to the bottom of the Bering Sea for the strongest evidence, for the coastlines of the time of the great migrations, and any remains of those earliest settlers, are now submerged. Model Might Be Valid
Dr. Brian M. Fagan, an anthropologist at the University of California at Santa Barbara and author of ''The Great Journey: The Peopling of Ancient America,'' conceded that the customary land bridge hypothesis may be ''simplistic, but it's probably still a valid model at this time.'' He noted that it is not known when humans began to live off the sea, but in Europe it was probably no earlier than 10,000 years ago.
''Whether or not the first Americans were coastal or not, we simply do not know,'' Dr. Fagan said. ''I still think probably the people were land hunters who may have taken some sea mammals and fish seasonally, but the specialized maritime people probably evolved after the migrations.''
Of course, no one is sure when the migration began. The earliest firmly documented evidence for human occupation of America, fluted stone projectile points, puts the date at no more recently than 12,000 years ago. Since the continental land connection began to break apart 14,000 years ago, the crossing or crossings presumably came earlier. Discoveries of human artifacts in South America dating back 30,000 years or more have not been generally accepted by archeologists.
The prevailing theory has been that at least three separate waves of Asian migrants cross into North America, following the game through an ice-free corridor that ran across the land bridge and down the interior of Alaska and Canada into what is now the United States. Several sites of mammoth kills with stone weapons have been found in the Western states. Only later, archeologists have assumed, did some people branch off and head for the coastal life.
Dr. Fitzhugh, who is curator of ''Crossroads of Continents: Cultures of Siberia and Alaska,'' an exhibit at the American Musuem of Natural History in New York City that is running through March 25, said the most impressive new evidence for coastal migrations comes from recent excavations of settlements 6,500 to 8,000 years ago. In particular, he said, a site on Kodiak Island in the Pacific Ocean off Alaska is yielding thousands of stone and bone remnants of a ''very mature'' society that lived off the sea and seemed to have a more advanced culture than contemporaries in the American interior.
Philomena Knecht, an archeologist who is conducting research at Kodiak Island for her doctoral degree at Harvard University, said that from its tool remains the Ocean Bay culture that thrived on the island at least 6,500 years ago seemed to be as advanced in its technology then as were the first Eskimos encountered by the Russians in the late 18th century.
Among the 30,000 identifiable pieces of material Mrs. Knecht has found are bone tools and fish hooks, bone harpoons, tiny stone blades comparable to those found earlier in Siberia and the bones of the whales, seals, otters, walruses, fish and birds that the culture killed and ate. The people also had devised stone lamps that burned oil from sea mammals, suggesting these could have been the earliest Eskimos.
''We have definitive evidence of an early maritime culture,'' Mrs. Knecht said. ''Maybe they came here and developed that technology, but it looks more like they came here with that technology already in hand. They probably could not have crossed to Kodiak without strong boats and long experience using them.'' Kodiak Evidence Is Encouraging
Mrs. Knecht is excavating the settlement with the assistance of her husband, Rick Knecht, an archeologist with the Kodiak Area Native Association, and Dr. Donald Clark, curator of Yukon archeology at the Canadian National Museum of Man in Ottawa. She said she would leave it to others to speculate on the significance of the Ocean Bay culture in explaining the earliest migrations.
But proponents of the maritime hypothesis, like Dr. Fitzhugh and Dr. Loughlin, find the Kodiak evidence encouraging. Even more ancient artifacts, 8,000-year-old stone tools, have been found on the Aleutian island of Anangula, which must have had a maritime culture.
Although the presumed early maritime migrants did not necessarily need boats, advocates of the hypothesis argue that there is no reason to assume they could not have developed sturdy boats made of hides. To support their idea they point to the sea migrations of Asians to Australia nearly 40,000 years ago. But Dr. Fagan cautioned that traveling by boat in tropical waters would have been a much easier accomplishment than any migration by boat in frigid waters.
Dr. Thomas Ager, an expert in Arctic studies and head of the climate-change program at the United States Geological Survey in Reston, Va., said investigations into the ecology of the Bering Strait region 25,000 to 13,000 years ago ''paint a pretty grim picture of climate conditions'' for a crossing either at the interior of the land bridge or along the southern coast. There would have been few large animals in the interior, he explained, and the coast would have been ice-bound most of the year, which would limit the types and number of organisms for sustaining a rich sea life.
Looking at both sides of the argument, Dr. Steven Young, a paleoecologist at the Center for Northern Studies near Stowe, Vt., concluded: ''There's almost nothing by way of hard evidence to back up either scenario. In view of this, we don't have to make a choice. It may be very likely that both groups, hunters and maritime people, came across at about the same time.''
But Dr. Young agreed that the image of the first migrants is changing because of new discoveries of settlements in Siberia at this time. ''We're beginning to understand that these were not just a bunch of poor Stone Age hunters straggling along at the fringe of existence,'' he said.