Models of migration to the New World
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This article is a basic look at the more popular models of migration to the New World.
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[edit] Overview
The question of how and when humans first entered the Americas has been debated for centuries. A number of hypotheses have been proposed by the anthropological community that explain migration into the Americas. As new data is discovered, these hypotheses are constantly reevaluated.
[edit] Understanding the Debate
The chronology of migration models is divided into two general schools of thought. One school believes in a “short chronology,” with the first movement into the New World occurring no earlier than 14,000 – 16,000 years ago. The “long chronology” camp posits that people entered the hemisphere at a much earlier date, possibly 20,000 years ago or earlier.
One factor fueling the debate is the discontinuity of archaeological evidence between North and South America. North American sites tend to reflect a more or less uniform techno-complex pattern known as Clovis from at least 13,500 years ago onwards, evidence of which has been found throughout North America and Central America.
Their South American counterparts, on the other hand, do not share the same consistency and exhibit more diverse cultural patterns. Thus, many archaeologists conclude that the Clovis model is not valid for the Southern Hemisphere, calling for new theories to explain prehistoric sites that do not fit into the Clovis tool techno-complex in South America. Some theorists are seeking to develop a Pan-American colonization model that integrates both North and South American archaeological records.
[edit] Land Bridge theory
The “short chronology” theory has been widely accepted since the 1930s. This model of migration into the New World proposes that people wandered from Siberia into Alaska, tracking big game animal herds. They were able to cross between the two continents by a land bridge called the Bering Land Bridge, which spanned what is now the Bering Strait. During the Wisconsin glaciation, the last major stage of the Pleistocene beginning 50,000 years ago and ending some 10,000 years ago, when ocean levels were 60 meters lower than today. This information is gathered using oxygen isotope records from deep-sea cores. An exposed land bridge that was at least 1,000 miles wide existed between Siberia and the western coast of Alaska. From the archaeological evidence gathered, it was concluded that this culture of big game hunters crossed the Bering Strait around 12,000 years ago and must have eventually reached the southern tip of South America by 11,000 years ago.
A recent molecular genetics study suggests that the Amerindian population in the Americas may be derived from a theoretical founding population with an effective size of as small as 70[1]. The Hey study is restricted to 9 genomic regions (or loci) in the Americas and Asia, and excludes speakers of Na-Dene and Eskimo-Aleut languages. The study does not address the question of separate migrations for these groups, and excludes other DNA datasets not sampled in the source literature.
It has been noted that Amerindian groups in the Arctic exhibit perhaps the strongest DNA or mitochondrial DNA relations to Siberian peoples. Amerindian groups in other geographical locations (such as Southwestern USA, Mesoamerica, and South America) share fewer genetic traits with arctic Amerindians and Siberians.
[edit] Synopsis
At the height of the last Ice Age, about 17,000 years ago, as the ice sheets advanced and sea levels fell, people first migrated from the Eurasian landmass to the Americas. These nomadic hunters were following game herds from Siberia across what is today the Bering Strait into Alaska, and then gradually spread southward. Based upon the distribution of Amerind languages and langugage families, a movement of tribes along the Rocky Mountain foothills and eastward across the Great Plains to the Atlantic seaboard is assumed to have occured some 10,000 years ago.
[edit] Clovis Culture
This big game hunting culture was known as Clovis, which is identified with fluted projectile points. It received its name from Clovis artifacts found near Clovis, New Mexico, the first evidence of this tool complex, excavated in 1932. Clovis ranged over much of North America and even appeared in South America. The culture is identified by distinctive "Clovis point", a notched flute in flint spear-points where a shaft was inserted. This flute is one characteristic that defines the Clovis point complex.
[edit] Problems with Clovis migration models
However, there are significant problems with the Clovis migration model. If Clovis people radiated south after entering the New World and eventually ended up at the southern tip of South America by 11,000 years ago, this leaves only a short time span to populate the entire hemisphere. Another complication for the Clovis-only theory arose in 1997, when a panel of authorities inspected the Monte Verde site in Chile, concluding that the radiocarbon evidence predates Clovis by at least 1,000 years. This makes it difficult to defend the theory of a north-to-south population movement. It is also worth noting that many excavations have uncovered evidence that early hunters also consumed less glamorous foods, such as turtles, shellfish, and tubers. This is quite a change of diet from the big game mammoths, long-horn bison, horse, and camels that early Clovis hunters apparently followed east into the New World.
At a site named "Topper" along the Savannah River near Allendale, South Carolina by University of South Carolina archaeologist Dr. Albert Goodyear have found traces of carbon among human artifacts. The charcoal material has been radiocarbon dated by the University of California at Irvine Laboratory to be at least 50,000 years old. This indicates the presence of humans well before the last Ice Age. Other pre-Clovis sites have been found recently in South America.
[edit] Watercraft Migration theories
This leads to a pre-Clovis culture theory and a variety of differing migration models to explain the problems associated with the Clovis-based theory. Moving into a “long chronology” model requires a new way of looking at the Americas. One method is to look toward an entirely different continent, Australia. There have been well-dated stratigraphic studies that point to people entering Australia some 40,000 years ago. At this period Australia was not connected to another continent, which leads to the assumption that it was reached by watercraft. If Australia was reached in this fashion, it only seems reasonable that the same could be applied to models of migration to the New World. This school of thought has developed a coastal migration route of pre-Clovis culture.
A recent study by Brian Kemp and colleagues (to be published in The American Journal of Physical Anthropology) reports new DNA-based research that uniquely links the DNA retrieved from a 10,000-year-old fossilized tooth from an Alaskan island, with specific coastal tribes in Tierra del Fuego, Ecuador, Mexico and California.[2] Unique markers found in DNA recovered from the Alaskan tooth were found in these specific coastal tribes, and were rare in any of the other indigenous peoples in the Americas. This finding lends substantial credence to a migration theory that at least one set of early peoples moved south along the west coast of the Americas in boats. A previous study (Eshleman et al. 2004) showed that mtDNA from indigenous populations in coastal British Columbia showed similarities to coastal populations in Southern California, while inland populations in both localities differed markedly.
[edit] Pacific coastal model
The Pacific coastal model proposes that people reached South America before North America following a Pacific route of water travel. Support for this argument is based on sites such as Monte Verde in southern Chile and Taima-Taima in western Venezuela. Two cultural components were discovered at Monte Verde. The youngest layer is radiocarbon dated at 12,500 years, while the older component possibly dates back as far as 33,000 B.P. However, the older dates associated with the site are still debated.
Some anthropologists propose that peoples of Oceania or southeast Asia crossed the Pacific Ocean and arrived in South America long before the Siberian hunter-gatherers. These hypothetical Pre-Siberian American Aborigines populated much of South America before being nearly exterminated and/or absorbed by the Siberian migrants coming from the north. Some of the theories involve a southward migration from Australia and Tasmania, hopping Subantarctic islands and then proceeding along the coast of Antarctica to the tip of South America sometime during the last glacial maximum.
Other coastal models deal specifically with the peopling of the Northwest Coast. Carlson (1990 in Matson and Coupland, 1995:61-61), argues for a coastal migration from Alaska pre-10,000 B.P. that predates the migration of Clovis people moving south through an ice-free corridor located near the continental divide (Matson & Coupland, 1995:64). These people were followed by the Clovis culture, which moved south from Alaska through an ice-free corridor located between modern British Columbia and Alberta. As the ice sheets began to melt, it became possible for these riverine-adapted peoples to move west to the Northwest coast. A second migration of the Denali culture at around 10,700 b.p. brought peoples down the coast from Alaska. Carlson hypothesizes that a population with a maritime adaptation would have travelled south from Alaska down the coastal islands by watercraft, settling as the ice receded, then moving up rivers to the interior. This would account for early finds at Ground Hog Bay in SE Alaska and Namu, about 800 km south of Ground Hog Bay near modern Bella Colla dating to 10,180 +/- 800 b.p. and 9700 b.p., respectively. According to the Matson and Coupland dual migration hypothesis, Namu and Ground Hog Bay represent a second migration while the initial migration route south was through the ice free corridor. Part of the difficulty is the lack of site data prior to 10,000 b.p. as well as the limited number of archaeological investigations into the coastal migration model. Other factors affecting migration models are sea level changes and the question of available land mass to support migrating groups of people.
Evidence from Haida Gwaii, also known as the Queen Charlotte Islands in British Columbia, provides some data about food and land resources during the last glacial maximum. Fedje and Christensen (1999) have identified several sites on Haida Gwaii that date to post 9000 b.p. (642). Their data suggests that there are a number of submerged sites just beyond the shorelines of Haida Gwaii (Fedje & Christensen, 1999). Paleoecological evidence suggests that travel along the coast would have been possible between 13,000 and 11,000 b.p. as the ice sheets began retreating (Matson & Coupland, 1995:64). Between 13,000 and 10,500 b.p. Haida Gwaii had more than double its current land mass (Fedje & Christensen, 1999:638). This area was flooded as the ice sheets began to melt between 11,000 and 9,000 b.p. (Ibid). Therefore any evidence of human occupation would now be below sea level. Conversely, older sites that are located near modern shorelines would have been approximately 15m from the coast (Ibid). The antiquity of the lithic scatters that Fedje and Christensen (1999) have reported finding in intertidal zones along the Haida Gwaii coast is suggestive of early human occupation of the area.
Fedje and Christensen (1999) support Carlson (1990), and Fladmark's (1975, 1979 &1989) initial coastal migration model rather than the ice free corridor model proposed by Matson and Coupland (1995) through their investigations of intertidal zones on Haida Gwaii (in Fedje & Christensen, 1999:648). The coastal region was quite hospitable by 13,000 b.p. to peoples with watercraft and a maritime adaptation (Fedje & Christensen, 1999:648). Furthermore, Fedje and Christensen (1999) argue that the coast was likely colonized before 13,000 b.p. (648). This assertion is based largely on watercraft evidence from Japan and Australia before 13000 b.p. (Fedje & Christensen, 1999:648). It is speculated that if peoples elsewhere at 13,000 b.p. could build boats then the possibility exists that migrating human groups could have produced watercraft to travel south from Beringia. There have been no water vessels recovered along the Northwest coast from this time. This may be due to poor preservation of organic materials, the inundation of coastal areas mentioned above, or that boats were not common 13,000 years ago. We can only infer water travel based on the presence of stone tools manufactured by humans found on island sites.
Other evidence comes from zooarchaeological finds along the Northwest coast. Goat remains as old as 12,000 b.p. have been found on Vancouver Island, British Columbia as well as bear remains dating to 12,500 b.p. in the Prince of Whales Archipelago, British Columbia (Ibid.). This means that there were enough land mass and floral resources to support large land mammals and theoretically, humans. Further intertidal and underwater investigations may produce sites older than 11,000 b.p.. Coastal occupation prior to 13,000 b.p. would allow for people to migrate further south and account for the early South American sites.
More compelling evidence comes from the surviving Bella Bella oral tradition as recorded by Franz Boas in 1898. "In the beginning there was nothing but water and ice and a narrow strip of shoreline" (Boas, 1898:883 in Fedje & Christensen, 1999:635). This story most likely describes the Northwest coast during the last glacial maximum and suggests that the Northwest coast colonization occurred during the last ice age.
[edit] Atlantic coastal model
Archaeologists Dennis Stanford and Bruce Bradley champion the coastal Atlantic route. However, their hypothesis still bases evidence from the Clovis complex, but associates it with the Europeans’ Solutrean tradition. They have hypothesized that Solutrean hunters and fishers may have worked their way along the southern margins of the Atlantic sea ice into the New World. Their argument is based on the similarities between the Solutrean and Clovis flint knapping techniques.
[edit] Problems with coastal migration models
The coastal migration models have provided a new look at migration in the New World, but they are not without their own problems. One of the biggest problems is collecting data for these theories. The coastline of the Pleistocene is now under 60 meters of water. This makes excavation rather difficult and probably unreachable until the utilization of underwater technology advances. If there was an early pre-Clovis coastal migration, there is always the possibility of a “failed colonization.” Of course as mentioned, evidence of this would be under 60 meters of water. Another problem that arises is the lack of hard evidence found for a “long chronology” theory. No sites have been able to produce a consistent date that is older than 12,000 years. When one considers the number of academic and CRM projects constantly producing radiocarbon dates, this becomes a staggering blow to the theory. There is also the possibility that archaeologists aren’t even identifying the tool technology of pre-Clovis sites. Early tools might have been crude stone flakes, edge-trimmed cobble tools, and tools of perishable bone that North and South American archaeologists could easily overlook.
[edit] Other theories
In his book "Columbus Came Last", Hans-Joachim Zillmer discusses the presence of Celtic peoples since the 3rd millennium B.P. in North America, i.e. the Celts-in-America theory. Zillmer identifies purported Celtic menhirs and dolmen sites as well as discoveries of Roman and Celtic coins in America. During this period, according to Zillmer, there was a land connection between North America’s East coast via Greenland and Iceland all the way to Europe, the so-called "Greenland bridge". This land bridge allowed the Celts to travel to both Europe and North America from their arctic homeland, the "Land of Eternal Spring." Zillmer's theory is not taken seriously by most scholars.
[edit] Notes
[edit] See also
- Pre-Columbian trans-oceanic contact
- Haplogroup X (mtDNA)
- Pre-Siberian American Aborigines
- Paul Rivet, one of the first ethnologists to tie the migration to America to Australia and Melanesia
[edit] References
- Jason A. Eshleman, Ripan S. Malhi, and David Glenn Smith, "Mitochondrial DNA Studies of Native Americans: Conceptions and Misconceptions of the Population Prehistory of the Americas", Evolutionary Anthropology, 12:7–18 (2003)
- Jody Hey, "On the Number of New World Founders: A Population Genetic Portrait of the Peopling of the Americas", Public Library of Science Biology, 3(6):e193 (2005).
- Hans-Joachim Zillmer: Columbus came last Celts-in-America-Theory.
- Matson and Coupland. The Prehistory of the Northwest Coast. Academic Press. New York. 1995.
- Fedje, & Christensen. Modeling Paleoshorelines and Locating Early Holocene Coastal Sites in Haida Gwaii. American Antiquity, Vol. 64, #4, 1999. Pp. 635-652.
[edit] Further reading
- Adovasio, J. M., with Jake Page. The First Americans: In Pursuit of Archaeology’s Greatest Mystery. New York: Random House, 2002.
- Lauber, Patricia. Who Came First? New Clues to Prehistoric Americans. Washington, D.C.: National Geographic Society, 2003.
- Snow, Dean R. “The First Americans and the Differentiation of Hunter-Gatherer Cultures.” In Bruce G. Trigger and Wilcomb E. Washburn, eds., The Cambridge History of the Native Peoples of the Americas, Volume I: North America (Cambridge: Cambridge University Press, 1996), 125-199.
- Sorenson, John L. and Johannessen, Carl L. (2006) "Biological Evidence for Pre-Columbian Transoceanic Voyages." In: Contact and Exchange in the Ancient World. Ed. Victor H. Mair. University of Hawai'i Press. Pp. 238-297. ISBN-13: ISBN 9780824828844; ISBN-10: ISBN 0824828844
