Models of migration to the New World

The question of when humans first entered the Americas (the "New World") and how they arrived has been debated for centuries, and will probably continue to be for many more years to come in the anthropological community. A number of theories have been proposed over the years that explain the migration into the Americas, but as new data is recovered, these theories are continually restructured. The following is a basic look at two of the more popular models of migration to the New World.

Two Theories of Migration

To start things off with a simple and broad approach, the variety of models have fallen in place between two different camps. One school of thought believes in a “short chronology,” believing that the first movement into the New World occurred no earlier than 14,000 – 16,000 years ago. On the other hand, the “long chronology” camp posits that people entered the hemisphere at a much earlier date, theorizing the possibility of migration 20,000 years ago or earlier.

Understanding the Debate

Part of the problem that arises between these opposing views is the relationship of archaeological evidence between North and South America. North American sites usually take a uniform techno-complex pattern known as Clovis, evidence of which has been found throughout North America and Central America.

Their South American counterparts, on the other hand, don’t share this consistency and have a large diversity in cultural patterns. Therefore, South American archaeologists didn’t believe the Clovis model applied in the Southern Hemisphere. This brought about new theories that were developed to explain prehistoric sites that didn’t fit into the Clovis tool techno-complex in South America. However, there is now a growing effort to develop a Pan-American colonization model that integrates both North and South American archaeological records.

Land Bridge theory

Many people are familiar with the “short chronology” theory, which 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, ocean levels were 200 feet 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, this culture of big game hunters crossed the Bering Strait around 12,000 years ago and eventually reached the southern tip of South America 11,000 years ago.

Recent evidence from molecular genetics suggests that the entire Amerindian population of the Americas may be derived from an effective founding population that could have been as small as 80 (Source: Hey, 2005).

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 graudually spread southward. Based on linguistic research, some 10,000 years ago, a movement of tribes occurred along the Rocky Mountain foothills and eastward across the Great Plains to the Atlantic seaboard.

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.

Problems with Clovis migration models

However, there are some real 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. Frustrating matters more, in 1997 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.

A recent discovery of a very old site (pre-Clovis) indicates that migration to the Americas occurred much earlier (before the Bering Strait was exposed).

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 recent pre-Clovis sites have been found in South America.

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.

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 and Tiama-Tiama. Monte Verde consists of two cultural components. 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 archaeologists have proposed 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 are claimed to have overspread much of South America before being nearly exterminated by the Siberian migrants coming from the north.

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). According to Matson and Coupland (1995) the New World was populated by a people, later known as Clovis, who 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 (Ibid). A second migration of the Denali culture at around 10,700 b.p. brought peoples down the coast from Alaska (Matson & Coupland, 1995). Carlson (Ibid.) 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. Carlson argues that this would account for the earliest components at Ground Hog Bay in SE Alaska and Namu, about 800 km south of Ground Hog Bay near modern Bella Colla. The earliest component at Ground Hog Bay dates to 10,180 +/- 800 b.p. and contains mostly biface fragments (Matson & Coupland, 1995:62). Namu's earliest component dates from around 9700 b.p. and contains remains of a pebble tool tradition (Ibid). However compelling the Namu and Ground Hog Bay data is, the dates recovered do not discount Matson and Coupland's (1995) ice free corridor hypothesis. According to the Matson and Coupland (1995) 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. Was there enough ice free land to support migrating groups of people prior to 10,000 years b.p.? What resources if any would be available and what were the technological capabilities of the migrating populations?

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 13000 and 11000 b.p. as the ice sheets began retreating (Matson & Coupland, 1995:64). Between 13000 and 10500 b.p. Haida Gwaii had more than double its current landmass (Fedje & Christensen, 1999:638). This area was flooded as the ice sheets began to melt between 11000 and 9000 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 13000 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 13000 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 13000 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 or the fact that there were no boats built 13000 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 12000 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. Therefore, human occupation was possible at this time. Fedje and Christensen (1999) state that further intertidal and underwater investigations will produce sites older than 11000 b.p. Coastal occupation prior to 13000 b.p. would allow for people to migrate further south and account for the early South American sites.

More compelling evidence comes from Bella Bella oral tradition 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. It is interesting that this description survived in Bella Bella oral history up to Boas' time. This suggests that colonization of the Northwest coast occurred during the last ice age. Obviously the ice sheets left a significant impression if their description became part of the Bella Bella origin stories.

Works Cited 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.

Atlantic coastal model

Archaeologists Dennis Stanford and Bruce Bradley champion the coastal Atlantic route. However, their theory 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.

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.

Conclusion

Although it may seem that there is still a great deal of guesswork associated with these migration models, the theories are constantly being revised and a greater emphasis in using New Archaeology has been applied. North and South American archaeologists now have a greater exchange of ideas and even look toward their European peers for new insight into this topic. However, there will probably always be debate surrounding this issue until more evidence is gathered. In conclusion, the point is not favoritism towards any one particular model, but awareness of the possibility of the antiquity of people in the New World and a continuing need for future archaeologists to further investigate the matter.

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).

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