If the first Americans migrated south along the coast, they would have had constant and reliable sources of nutritious food as well as an efficient way to travel. |
By Tabitha M. Powledge
Walking on two feet is a defining human characteristic, and two feet carried our progenitors out of Africa to people the planet. Archeologists have long thought that people originally came to the New World as pedestrians, too. This walk was possible because a long-gone land bridge known as Beringia linked Asia with the Americas when seawater locked away in Ice Age glaciers made sea levels hundreds of feet lower than they are now.
And then, the story goes, the immigrants continued to walk: through a temporary ice-free corridor down the interior of Canada, farther south through the United States to Mexico and Central America, then along the spine of the Andes until, after a 10,000-mile hike, they arrived at Monte Verde in southern Chile before 12,800 years ago.
Ten thousand miles is a very long walk in a few hundred years. It's not an impossible trip; moving 20 miles south every year for 500 years would do it. But it would be grueling.
That is one reason why some specialists in New World settlement are reviving an old question. What if some of the first Americans wanted to get from the frigid north to salubrious southern weather as quickly and comfortably as possible? What if they used their heads instead of their feet? What if they came by boat?
The idea that the Americas were settled originally by boat came ashore with Columbus. Most of the early theorists argued for an Atlantic crossing-by the Carthaginians, or the Lost Tribes of Israel, or those perennial imaginary refugees from drowned Atlantis. But as early as the sixteenth century, Jesuit missionary Jose de Acosta speculated that the first Americans came from Asia, largely on foot- with, however, short stretches of navigation.
At its formal beginnings in the mid-nineteenth century, American archeology embraced the idea that Asians immigrated partly by boat. By the end of the century, however, it was known that the Bering Strait had been dry for a time. Boats had not been necessary after all. Ideas about early American migrations have since been dominated by a wholly pedestrian paradigm.
| "There's something about the ice-free corridor, it's just this macho origin myth kind of thing." |
But some of today's archeologists wonder if the missionary's position has merit after all. A quick push south by boat would help untangle some of the perennial puzzles about New World settlement; for example, why the oldest occupation sites seem to be in places like the U.S. Southwest and South America, instead of Alaska, where one might reasonably expect to find them, and how the hemisphere was peopled so swiftly. Immigrants, they think, could have traveled by water at least part of the way, heading south in a series of coastal hops, camping for a time here and there along the shore and even inland, and then moving on.
A small number of scientists have begun to examine this revisionist account of the earliest American migrations. One of them is Jon Erlandson of the University of Oregon, who has led investigations at Daisy Cave, dated at about 10,200 radiocarbon years ago. (All the dates in this article are in radiocarbon years, which are about 2,000 years younger than dates in calendar years.)The site demonstrates the early use of ocean-going watercraft. Daisy Cave is on San Miguel Island in southern California, and the only way to get there, even when the seas were lower, was by boat.
"There are more resources along the coastlines, probably even along the coastlines of Beringia as well. I see it as a potentially more attractive and more productive type of environment that humans could have followed," Erlandson argues. "Hugging the coast, there's always going to be shellfish, there's always going to be fish, there's always going to be sea mammals and sea birds," he says. "If you're adapted to those resources in the North Pacific, you're going to find them in various forms all the way from there to southern South America. That, to me, makes a long-distance migration over a relatively short period much, much easier than taking an interior route."
Research by Carole Mandryk, a paleoecologist at Harvard University, has shown that people could not have headed south through the theoretical ice-free corridor east of the Mackenzie Range in glaciated North America until 12,000 years ago at the earliest.
At 12,800 years old, Monte Verde is now officially acknowledged to be the oldest archeological site in the Americas. "Since the corridor was closed when people had to have been going to Monte Verde, the first people must have gone down the coast," Mandryk argues. "I always like to point out that it's not an either/or kind of question. It can be both. I just think that people came down the coast first, and I think people came down the coast fairly quickly."
The strongest advocate of coastal migration is E. James Dixon, of the Denver Museum of Natural History, who described some of his ideas in Quest for the Origins of the First Americans, published in 1993. He detected a shift in opinion among his colleagues at a 1997 Colorado conference on Beringia. "For the first time I think many scientists felt that this hypothesis better explained the peopling of the Americas than the traditional continental interior model. But there still is not consensus."
Like the pedestrian notion, the boat hypothesis assumes that the first Americans came from Asia some time after 20,000 years ago. It also assumes that they walked-but only sometimes. Part (or much or most) of their journey was by boat. Some theorists think they may have voyaged from Asia along the southern coast of Beringia; others think that's possible but not necessary. Nor were the frigid northern waters a deterrent. "Once they reached the shores of southern Beringia there are no major barriers. Just follow the coastline. We don't have to be talking about long-distance marine voyages," Erlandson says.
The orthodox view had migrants walking over the Bering land bridge and then along an inland corridor through what is now Canada and the United States and down into Central and South America. |
The technology was certainly available. People have been messing about in boats for many thousands of years, on rivers and lakes before they finally went to sea. Boats were an essential tool for one of the most spectacular human migrations ever: the settlement of the Pacific. Homo sapiens voyaged to Australia from the Indonesian archipelago by at least 30,000 years ago. Pacific settlement specialist Peter Bellwood, of Australian National University, suggests that some evidence points to an arrival as early as 50,000 or 60,000 years.
Does that mean America could have been settled by direct Pacific crossings? The archeologists say not. "I don't think you can read anything necessarily from the Pacific situation to the Americas," says Patrick Kirch, of the University of California at Berkeley, specialist in Pacific colonizations of the last few thousand years. He believes Pleistocene occupation of Oceania was deliberate and by boat because it was quick and involved multiple water gaps. "But they never got beyond the end of the Solomons until 3,200 years ago, when the Lapita people charged through with outrigger canoes and sails," Kirch points out. Says Bellwood, "Nothing in eastern Polynesia is over 2,000 years old, and most is closer to 1,000."
Thus the northern coastal route via Beringia is still the first Americans' most plausible channel to the New World.
Bellwood believes the earliest voyaging was by bamboo raft, and the voyages may even have been made without a paddle. So when Mark Twain sent Huck and Jim down the Mississippi on a homemade raft, he was honoring what is probably humanity's oldest aquatic conveyance. Simple canoes are another possibility. By 13,000 years ago, the Pacific islanders had definitely shaped stone adzes into tools for turning huge logs into safe, dry, and comfortable dugout canoes, although the dugout may be considerably older. The sail, fabricated at first perhaps from grass matting, may be ancient, too. Or maybe not; much Pacific island settlement was over short spans of water and could have taken place without sails.
We will probably never know for certain, because watercraft are not well represented in the archeological record. The most ancient discovered so far are only 10,000 years old-log boats that have turned up in Europe. Watercraft can be made out of just about anything that floats, but, unlike the fiberglass in today's boats, these materials are extremely perishable-animal hides stretched over a lightweight wood frame, trees and their bark, basketwork, even pottery. If the first Americans came by boat, the experts think, their craft were likely to have been skin canoes.
The ice-free corridor down through Canada's interior, the most popular depiction of early American migration since the 1950s, is looking more and more like a fable. The corridor once was portrayed as a broad green valley full of mammoths, who had never seen a hunter, guilelessly awaiting the spear and the spit, with your choice of toothsome berries and other meltingly sweet treats for dessert. It was a Disneyesque combination Garden of Eden and Pleistocene superhighway that filled the immigrants' bellies with one delicious mouthful after another while beckoning them onward to the sunny south.
There have always been a few naysayers who doubted that the supposed corridor was an Ice Age Yellow Brick Road. Their skepticism has been validated during the last decade by careful studies of stratigraphy, rockfall patterns, and distribution of plants and animals in Canada and Alaska. These have confirmed that during the last glacial epoch the supposed "corridor" was icebound and impassible. And when the glaciers retreated, they left behind a swampy, stony wasteland that would have been a desperate trial to pass through, a narrow, icy wind-tunnel from Hell, full of frightful barriers-great boulders and frigid meltwater lakes and residual glaciers-and sorely lacking vegetation and the edible animals that feed on it.
The discovery of 12,800-year-old evidence of human occupation at Monte Verde, in southern Chile, raised old questions about how the earliest immigrants to the New World got here, and how they moved south once they arrived. |
Mandryk stumbled accidentally into the ice-free corridor almost a decade ago in pursuit of a dissertation topic. She believed the crucial issue was the corridor's environment. "Even when the ice is starting to disappear, it would be this really swampy, yucky area. But that's not really the problem. The problem is, is there vegetation? Are there animals?"
So she set out to look for them, taking core samples from three fossil lakes in Alberta that would have been at the southern end of the corridor. When Mandryk looked for pollen in the dated layers of her sample cores, she discovered that the study area had remained lifeless for thousands of years after the ice began to pull back. There was not even enough vegetation in 1,000 square miles to support the animals that a band of 15 people (the minimum size for a migrating group, anthropologists have calculated) could live on.
"At 18,000, 16,000, 14,000, and 13,000 years ago there just simply wasn't enough biomass in the environment to support people," Mandryk says. "But very quickly it changed and improved, so that 12,000 years ago they could have made it and 11,000 years ago it was wonderful."
Even if the pollen studies had left the door to the ice-free corridor ajar in southern Canada, recent research in the Richardson and Mackenzie Mountains further north has pretty much slammed it shut. In the past few years, several geologists have shown that the ice reached its maximum extent and blocked the northern portion of the corridor as early as 30,000 years ago and didn't retreat until after 12,000.
Therefore, although it was available to later waves of migrants-and there were probably several such groups-the corridor was the road not taken by the Monte Verdeans' forebears.
Is it possible that the first Americans came much earlier than is customarily thought, before ice blocked the way? The handful of American archeological sites of claimed great age-such as Meadowcroft Rock Shelter in Pennsylvania (20,000 years ago) and Pedra Furada in Brazil (40,000 years ago)-are regarded as dubious, and there is as yet no firm evidence that there were Americans much before Monte Verde's 12,800 years ago. It also appears unlikely that there could have been. "There was nobody to come because there was nobody in western Siberia until 25,000 years ago," Mandryk says. And, she points out, the earliest accepted archeological site in Beringia is only about 14,000 years old.
Since early in this century, geologists have known that the upper Pacific coast of North America was never entirely glaciated during the last Ice Age; in many places, for example, the telltale signs of glacial rock scouring are absent. Some researchers inferred that these ice-free coastal pockets functioned as comparatively temperate and productive sanctuaries that sheltered many animals and plants through the Ice Age, and might well have sheltered people, too.
The coastal migration variant of that idea has been around for almost 40 years. It was proposed-ever so gently-in an exhaustive examination of late-Pleistocene geology and paleo-climatology of the northern Pacific coast of North America, published in 1960 by Calvin J. Heusser of the American Geographical Society. He pulled together many decades' worth of data on North American geology, historical climatology, volcanism, botany, and zoology, and then combined it with his own extensive radiocarbon dating of North American peat deposit stratigraphy and fossil pollen. In the process he showed that even at the height of the last Ice Age, the Pacific Northwest coast had been dotted with unglaciated pockets where unique plants and animals took sanctuary from the perpetual winter inland-and thrived. Heysser also cautiously averred that perhaps people came that way as well: "Some favor is attached here to early coastal migration in preference to the generally accepted belief of passage through the continental interior."
Few New World specialists attended to this diffident suggestion, but in the 1970s Knut Fladmark, of British Columbia's Simon Fraser University, took up the lonely banner. "The coastal route has always seemed to me to be a more reasonable route because no matter what time period you model that movement to have occurred, the coast was always a more inhabitable environment for people to occupy than any interior route, with more access to resources," he says. "That doesn't mean to say that the coast was necessarily an easy route in the Pleistocene, nor that it was always open."
For example, a significant glacial barrier in the south central Gulf of Alaska appears to have blocked any movement south until about 14,000 or 15,000 years ago, Fladmark says. The early date for the Monte Verde site poses no problem for him, however. "Movement along the entire coast could have occurred within 200 years if people were driven. It would have been quite easy for people to do that." Especially by boat.
Recent geological and environmental studies have made a piecemeal but fairly persuasive case that the coast was ice-free, or nearly so, when the terrestrial "ice-free corridor" was completely clogged. Daniel Mann, of the University of Alaska, and Dorothy M. Peteet, of the Goddard Institute for Space Studies, demonstrated in 1994 that even most areas of southwestern Alaska that were covered with ice during the Last Glacial Maximum, from about 23,000 to 19,000 years ago, were free of ice by about 15,000 years ago; vegetation-mostly heaths-reappeared at that time.
As more coastal archeological sites are discovered and dated, a picture of a relatively quick, coastal migration may begin to supplant the assumption of an inland route. |
Daryl Fedje, an archeologist at Parks Canada, participated in a long-term investigation in the Queen Charlotte Islands off the coast of British Columbia. His collaborator, Heiner Josenhans of the Geological Survey of Canada, has shown that glacial ice there was limited to very small local deposits. In a 1997 paper published in Science, they noted, "the Northwest Coast was suitable for human habitation by 13,000 years b.p." The landscape of the late-Paleolithic Queen Charlottes was no Arctic desert, either, but an open tundra with grasses, sedges, willows, and, eventually, trees.
Timothy Heaton of the University of South Dakota, along with Dixon, Erlandson, and others, has demonstrated that living conditions north of the Queen Charlottes, in the Alexander Archipelago, were hospitable enough for several Pleistocene mammals. They have found the remains of 15 grizzly bears whose bones date from 12,300 to 7,200 years ago, and one that appears to be more than 35,000 years old.
Erlandson is particularly happy about the grizzly bears. Like humans, grizzlies dine on both the animal and the vegetable kingdoms. "You have to assume that if the landscape could support brown bears then it could also support humans."
In the summer of 1996, Dixon studied some very old human bones that ancient predators had strewn around one of the hundreds of newly discovered caves in Tongass National Forest in southeast Alaska. A jawbone with its teeth, a bit of pelvis, some fragments of ribs, and a few vertebrae are all that is left of a man who met death at around the age of 20. The remains have been radiocarbon-dated to 9,200 years ago, which makes them the oldest human remains found north of the Canadian border.
This site, at first called, vividly, On-Your-Knees Cave, is now formally known by its Federal site designation, 49-PET-408. It is on Prince of Wales Island, which, despite its royalist moniker, claims to be the third-largest island in the United States. Thus the doomed young man could have reached his final destination only by boat.
Researchers also found remains of campfires, stone tools, and evidence of tool-making at the site. Some of the tools are obsidian, highly prized for its exceptionally sharp edge but available nowhere on Prince of Wales Island. All of which means, Dixon argues, that boat technology must have been well advanced there quite early. People were fully adapted to a maritime economy, engaged in offshore fishing, and had set up an inter-island trade network, all before 10,000 years ago, he says.
Combined with the burgeoning details on northwestern glaciation history, the new finds at the On-Your-Knees Cave are helping to raise the boat hypothesis' profile considerably. "It's really sparked people's interest in the whole idea of coastal occupation," Fedje says. "And there's definitely a smoking gun in the bears and foxes and seals dating to very early times."
Fedje's own research in a now-drowned site in the Queen Charlottes has yielded no bones, human or otherwise. But he has dredged up a sharp stone tool from a portion of sea floor that would have been dry land 10,200 years ago. His is not an occupation site, he suspects, but rather a place where Pleistocene buddies hung out, engaging in guy stuff like fishing and hunting sea mammals, more than 10,000 years ago.
No early coastal sites have yet been found in Washington or Oregon, according to Erlandson. If there were any, he speculates, they may well have been inundated by the rising postglacial seas or pulverized by the region's chronic earthquakes. But further south, in Daisy Cave, the oldest North American coastal archeological site, people were feasting on seafood before 10,500 years ago. They came there to collect shellfish for thousands of years, and could not have done that without boats.
Slightly older South American coastal sites are found in Peru. But the evidence of boat use there is not incontrovertible, as it is at Daisy Cave. The people ate lots of fish, but they were small and could have been caught in nets flung from the shore.
Finally, Monte Verde itself contains firm evidence that people who lived there were also exploiting coastal resources by 12,800 years ago. Although the sea lay 37 miles to the west at that time, the Monte Verdeans either went to the coast themselves or had contact with coastal people. They used flat, discoid beach pebbles as grinding stones, they made use of at least three different species of salt-water seaweeds, and they ate several kinds of plants that grow only in brackish water.
Since Heusser's exhaustive 1960 study, the coastal migration hypothesis has always been plausible enough to deserve a hearing. Yet all but a handful of New World settlement specialists have disdained even to discuss it. The reasons may have more to do with sociology than they do with geology or archeology. Perhaps we have been enraptured by a primeval image of fur-covered hunters, spears at the ready, striding across the landscape in wily pursuit of mammoths.
"There's something about the ice-free corridor, it's just this macho origin myth kind of thing," Mandryk says. "People want to believe in it even though there has never been any evidence to support it. I've encountered people who simply refuse to believe that the corridor was closed," she says. "I've had people flatly tell me it had to be open because people went through it!"
What would count as confirmation of coastal migration by boat? Most of the partisans say they need a maritime human occupation site that-as archeologists like to say-breaks the Clovis barrier. Until Monte Verde was canonized as 12,800 years old in February 1997, Clovis, New Mexico, dated between 11,000 and 11,500 years ago, had since the 1930s held the record for being the oldest American human occupation site. Except for Monte Verde, it still does. So the hunt is on for a coastal site older than Clovis, ideally one that is around 14,000 years old.
"With advances in marine survey archeology, it would certainly be possible to find sites on the continental shelf," Dixon says. And, he points out, sometimes even flooded sites can yield tantalizing glimmers of very ancient coastal life. Fedje's research in the southern Queen Charlottes, at a study area the Haida Indians call Gwaii Hanas, managed to reveal terminal Pleistocene living sites, complete with stone tool kits, just below modern sea level, in the intertidal zone. Dixon noted, "There are underwater caves that are likely looking places. Also, there are elevated beach ridges where the land has actually been uplifted along coastal margins that would be good places to look."
For just that reason, Fedje himself hankers after the mountainous coast of British Columbia. He has hopes for the outer mainland coast, where the shores of 13,000 years ago are now 55 yards high; an investigation is planned for this summer.
University of Kentucky archeologist Thomas Dillehay, whose decades-long and ultimately successful campaign to persuade his colleagues that people lived at Monte Verde 12,800 years ago earns his ideas a respectful hearing, has another notion. He wants to look up the rivers that empty into the Pacific along the Andes or Baja California. "From what we know about prehistoric hunter-gatherer societies," he says, "they tended to go up and down rivers, so it stands to reason that if they were following the coast there must have been periodic movement up and down some of these rivers."
One of the best chances for convincing evidence of coastal migration may lie in Alaska, where Erlandson and his wife, archeologist Madonna Moss, have for the last few years been working with Dixon and other researchers, inventorying the Tongass caves and radiocarbon-dating old shorelines and artifacts. A couple of dozen caves have contained evidence of past human occupation, all of it younger than the human bones and tools at 49-PET-408. "So far we haven't found anything that dates earlier than Clovis. I think that we haven't looked as extensively as we'd like to," Erlandson says. There are hundreds of Tongass caves, and only a small proportion have been explored.
Dixon is convinced that they will find sites older than 49-PET-408. "It would be foolish to assume that we went out and found the very first coastal settlement in all of northwestern North America. There must be something much older than this," he declares.
Erlandson is more detached. Still, he argues, "This is such a fundamental question in American archeology that it really does need to be looked at. It can't just be dismissed any more, as it was for years."
Tabitha M. Powledge, author of Your Brain: How You Got It and How It Works, specializes in genetics, neuroscience, and science policy, but writes about archeology every chance she gets.
© Copyright 1999 by Tabitha M. Powledge. Text and photographic images are intended solely for on-screen viewing by individual user. The video screen content is not to be used for any purpose other than individual print out without the written permission of the copyright holder.
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