"Coastal Navigators--The First Americans May Have Come by Water"
If the foragers who created Clovis culture walked into North America, they had to pass through the long-described “ice-free corridor.”But a growing body of evidence indicates that pathway between the great glaciers of the last Ice Age was closed — in fact, the way south may have been blocked until centuries after the dawn of Clovis. If the first Americans could not walk into the New World, how did they get there? Coastal or ocean routes navigated by watercraft are the most likely explanation.
No reliably dated human remains from the Americas are older than about 11,500 radiocarbon years (13,350 calendar years). This, along with other evidence, suggests humans first arrived in the Americas not more than 15,000 years ago (17,950 cal BP), near the end of the last Ice Age, the Late Wisconsin.
The climate was much colder then, and massive glaciers in the east and west formed a huge ice sheet covering most of Canada. The ice blocked access between what is today Alaska and the continental United States. Polar sea ice extended south into the Atlantic, covering Greenland, Iceland, and all but the southernmost areas of Ireland and England.
Because much of the earth’s water was trapped in glacial ice, sea level was lower. The continental shelves and the floor of the Bering and Chukchi seas were exposed, creating the Bering Land Bridge. The geography of the Ice Age limited possible migration routes into the Americas to the following: the Beringian mid-continental, the Northwest Coastal, the Pacific, and the Atlantic routes. The Beringian mid-continental route presumes that hunters and gatherers first entered North America from Asia across the Bering Land Bridge.
They then moved south into central-western Canada through the hypothetical ice-free corridor. But geologists working in Canada have recently demonstrated that the “ice-free corridor” did not exist at that time, and that connections between eastern Beringia and areas south of the continental glaciers were not established until about 11,000 years ago (13,020 cal BP).
Supporting this conclusion, paleontologists have found no animal bones dating between about 21,000 to 11,500 years ago in the region formerly believed to have been the ice-free corridor. This evidence demonstrates fairly conclusively that the ice-free corridor did not exist during the last Ice Age. And it precludes a mid-continental route for human entry before about 11,000 years ago.
Deglaciation along the Northwest Coast of North America had begun by about 14,000 years ago (16,800 cal BP) and was sufficiently advanced to enable humans using watercraft to colonize coastal areas by 13,000 years ago (15,350 cal BP). The remains of land and sea mammals, birds, and fish dating to this time have been discovered along the Northwest Coast, demonstrating sufficient resources existed along the coast for people to have survived.
Because earlier geologic interpretations had indicated that the region had been entirely glaciated until about 10,000 years ago (11,350 cal BP), very little
archaeological work has been undertaken to explore this region as a possible migration route. So far, no sites have been found that are older than about 10,500 to 10,000 years ago.
Some researchers believe humans may have crossed the vast expanse of the Pacific and colonized South America before anyone reached North America. Support for this theory is based on sites such as Monte Verde in southern Chile and Tiama-Tiama in northern Venezuela, which may be older than the oldest sites in North America. Biological evidence suggests some of the earliest skeletons in South America may share similarities with inhabitants of Polynesia and Australia.
The Atlantic route is championed by archaeologists Dennis Stanford and Bruce Bradley, who have documented a surprising number of technological traits shared between the Clovis complex of North America dating to between 11,500 and 10,900 years ago and the Solutrean tradition of Europe, which ended possibly as late as 16,000 years ago (19,100 cal BP). They hypothesize that Solutrean maritime hunters and fishers may have worked their way along the southern margins of the Atlantic sea ice to the New World during the Late Wisconsin.
The preponderance of linguistic and biological evidence indicates that Native Americans most likely originated somewhere in northeastern Asia. Only the Northwest Coastal and mid-continental routes lead from there to the Americas. Because the mid-continental route was not open until about 11,000 years ago, the most plausible route for the initial colonization of the Americas seems to be along the Northwest Coast.
The colonization of continents is a complex process that spans a long period of time and probably involves many groups of people from different places. Archaeologists must keep their minds open to the many ideas being offered to explain the peopling of the New World.
There are tantalizing biological and technological clues that suggest possible contact, perhaps even colonization, between the Americas and Australia, Polynesia, Europe, and even Africa. The timing and processes of the colonization of the Americas are important because the cultural adaptations of the New World’s first populations established the foundation for all subsequent cultural development in the Americas and for the rich and diverse cultures that followed.
E. JAMES DIXON is Curator of Archaeology at the Denver Museum of Natural History. His latest book, Bones, Boats & Bison: Archeology and the First Colonization of Western North America, is in publication by University of New Mexico Press.
The Solutrean Solution--Did Some Ancient Americans Come from Europe?
by Dennis Stanford and Bruce Bradley
For half a century, archaeologists have assumed that ancestors of the Clovis people — long considered the first Americans — crossed the Bering Land Bridge from northeast Asia some 14,000 calendar years ago, then spread southward across the continent. But there is something wrong with that picture.
Years of research in eastern Asia and Alaska have produced little evidence of any historical or technological connection between the Asian Paleolithic (Stone Age) and Clovis peoples. Also, the southeastern United States has produced more Clovis sites than the West, and a few radiocarbon dates suggest some of them may predate those in the western states. If correct, that hardly fits the notion that Clovis technology originated in northeast Asia or Alaska.
Over the years, various scholars have noted similarities between Clovis projectile points and “Solutrean” points, the product of a Paleolithic culture on the north coast of Spain between 22,000 and 16,500 years ago. Little credence has been given to suggestions of a direct connection between these technologies because of the 4,500-year time gap between the last of Solutrean and the first of Clovis, and because of doubts that people of the Upper Paleolithic could navigate the Atlantic Ocean.
But indirect evidence for Paleolithic ocean travel has been mounting. Although no boats have been found, we now know that by at least 40,000 years ago, watercraft carried a founding population to Australia. By 28,000 years ago, flintknappers were collecting raw materials from islands far off the Japanese coast. And closer to Spain, Paleolithic peoples inhabited some of the Mediterranean islands at least 14,000 years ago.
Solutrean peoples could have used this knowledge of watercraft to travel and exploit marine resources, which would have been especially important during the last glacial maximum, about 18,000 years ago, when most of Europe was covered with ice and competition for diminishing land resources must have been intense. Given these facts, we believe the hypothesis of a western Old World ancestry for Clovis should be reconsidered.
To determine whether the idea was worth additional study, we examined archaeological collections in Spain, France, and Portugal, looking for technological affinities between the European Upper Paleolithic and Clovis. Our cursory examination revealed an amazing correspondence between Solutrean and Clovis; in fact, Solutrean has more in common with Clovis than with Paleolithic technologies that followed it in Europe.
Solutrean and Clovis flintknappers used nearly identical stoneworking technologies. We observed a high degree of correspondence between stone and bone tools, as well as engraved limestone tablets, and caching of extra large bifaces and other tool stock. The Solutrean toolkit is, with a few exceptions, nearly identical to that of Clovis. Although some of the Solutrean concave-base projectile points are heavily thinned, none that we saw exhibited a well-developed Clovis-style flute. Clovis assemblages lack shouldered points and the Solutrean laurel-leaf knife.
A Solutrean origin for the Clovis culture seems a more parsimonious explanation of the evidence than an Asian ancestry. Certainly, if Solutrean industries were found in Siberia, no one would question their historical relationship with Clovis.
The ultimate test of this hypothesis may be found in genetic research on ancient human remains. Michael Brown and colleagues reported in 1998 that mitochrondrial-DNA haplogroup X (a genetic marker of population groups) is found in low frequencies in both European and Native American populations, but not among Asians. This indicated to them that some of the American founders may have come from Europe between 36,000 and 12,000 years ago.
Regardless of whether a Solutrean-Clovis link is eventually proven, exploring this hypothesis should increase our understanding of the development of technological innovations and broaden our knowledge of early peoples of the New World.
DENNIS STANFORD is Chairman of the Anthropology Department at the National Museum of Natural History, Smithsonian Institution.