Settlement of the Americas
The question of how, when, where and why humans first entered the Americas is of intense interest to archaeologists and anthropologists, and has been a subject of heated debate for centuries. Several models for the Paleo-Indian settlement of the Americas have been proposed by various academic communities. Modern biochemical techniques, as well as more thorough archaeology, have shed progressively more light on the subject.
Current understanding of human migration to and throughout the Americas derives from advances in four interrelated disciplines: archeology, physical anthropology, DNA analysis and linguistics. While there is general agreement that the Americas was first settled from Asia by people who migrated across Beringia, the pattern of migration, its timing, and the place of origin in Asia of the people who migrated to the Americas remains unclear. In recent years, researchers have sought to use familiar tools to validate or reject established theories, such as Clovis first. As new discoveries come to light, past hypotheses are reevaluated and new theories constructed. The archeological evidence suggests that the Paleo-Indians' first "widespread" habitation of the Americas occurred during the end of the last glacial period or, more specifically, what is known as the late glacial maximum, around 16,500–13,000 years ago.
- 1 Understanding the debate
- 2 Genetics and blood type
- 3 Land bridge theory
- 4 Watercraft migration theories
- 5 Notes and references
- 6 Bibliography
- 7 See also
- 8 External links
Understanding the debate
The chronology of migration models is currently divided into two general approaches. The first is the short chronology theory, with the first movement beyond Alaska into the New World occurring no earlier than 15,000–17,000 years ago, followed by successive waves of immigrants. The second belief is the long chronology theory, which proposes that the first group of people entered the Americas at a much earlier date, possibly 21,000–40,000 years ago, with a much later mass secondary wave of immigrants.
One factor fueling the debate is the discontinuity of archaeological evidence between North and South American Paleo-Indian sites. A roughly uniform techno-complex pattern, known as Clovis, appears in North and Central American sites from at least 13,500 years ago onwards. South American sites of equal antiquity do not share the same consistency and exhibit more diverse cultural patterns. Archaeologists conclude that the "Clovis-first", and Paleo-Indian time frame do not adequately explain complex lithic stage tools appearing in South America. Some theorists seek to develop a colonization model that integrates both North and South American archaeological records.
|Dates BCE||Beringia "Land Bridge"||Coastal route||Mackenzie Corridor|
Indigenous Amerindian genetic studies indicate that the "colonizing founders" of the Americas emerged from a single-source ancestral population that evolved in isolation, likely in Beringia. Age estimates based on Y-chromosome micro-satellite place diversity of the American Haplogroup Q1a3a (Y-DNA) at around 10,000 to 15,000 years ago. This does not address if there were any previous failed colonization attempts by other genetic groups, as genetic testing can only address current population ancestral heritage.
Migrants from northeastern Asia could have walked to Alaska with relative ease when Beringia was above sea level. But traveling south from Alaska to the rest of North America may have posed significant challenges. The two main possible southward routes proposed for human migration are: down the Pacific coast; or by way of an interior passage (Mackenzie Corridor) along the eastern flank of the Rocky Mountains. When the Laurentide and Cordilleran ice sheets were at their maximum extent, both routes were likely impassable. The Cordilleran sheet reached across to the Pacific shore in the west, and its eastern edge abutted the Laurentide, near the present border between British Columbia and Alberta.
Geological evidence suggests that the Pacific coastal route was open for overland travel before 23,000 years ago and after 15,000 years ago. During the coldest millennia of the last ice age, roughly 23,000 to 19,000 years ago, lobes of glaciers hundreds of kilometers wide flowed down to the sea. Deep crevasses scarred their surfaces, making travel across them dangerous. Even if people traveled by boat—a claim for which there is currently no direct archaeological evidence, as sea level rise has hidden the old coastline—the journey would have been difficult with abundant icebergs in the water. Around 15,000 to 13,000 years ago, the coast is presumed to have been ice-free. Additionally, by this time the climate had warmed, and lands were covered in grass and trees. Early Paleo-Indian groups could have readily replenished their food supplies, repaired clothing and tents, and replaced broken or lost tools.
Coastal or "watercraft" theories have broad implications, one being that Paleo-Indians in North America may not have been purely terrestrial big-game hunters, but instead were already adapted to maritime or semi-maritime lifestyles. Additionally, it is possible that "Beringian" (western Alaskan) groups migrated into the northern interior and coastlines only to meet their demise during the last glacial maximum, approximately 20,000 years ago, leaving evidence of occupation in specific localized areas. However, they would not be considered a founding population unless they had managed to migrate south, populate and survive the coldest part of the last ice age.
Timeline of selected archaeological, geological and genetic evidence
|30,000–20,000 years ago:
(Note: The conclusions reached in Alberta on dates have not been accepted by the entire archaeology community.)
|23,000–16,500 years ago:
|16,500–13,000 years ago:
|15,000–13,000 years ago:
|13,500–12,000 years ago:
|12,000–10,000 years ago:
|9,000–8,000 years ago:
Genetics and blood type
By the 1920s studies indicated that blood type O was predominant in pre-Columbian populations, with a small admixture of type A in the north. Further blood studies combining statistics and genetic research were pioneered by Luigi Cavalli-Sforza and applied to population migrations predating historical records. This led Jacob Bronowski to assert in 1973 (in The Ascent of Man) that there were at least two separate migrations:
"I can see no sensible way of interpreting that but to believe that a first migration of a small, related kinship group (all of blood group O) came into America, multiplied, and spread right to the South. Then a second migration, again of small groups, this time containing either A alone or both A and O, followed them only as far as North America."
Modern Amerindian genetics studies focus primarily on human Y-chromosome DNA haplogroups (yDNA haplogroups) and human mitochondrial DNA haplogroups (mtDNA haplogroups). The genetic pattern emerging shows two very distinctive genetic episodes occurred, first with the initial peopling of the Americas, and secondly with European colonization of the Americas. The former is the determinant factor for the number of gene lineages, zygosity mutations and founding haplotypes present in today's indigenous Amerindian populations.
Genetics and blood studies indicate human settlement of the New World occurred in stages from the Bering sea coastline, with an initial layover on Beringia for the small founding population. The micro-satellite diversity and distributions of the Y lineage specific to South America indicates that certain Amerindian populations have been isolated since the initial colonization of the region. The Na-Dené, Inuit and Indigenous Alaskan populations exhibit haplogroup Q (Y-DNA) mutations, but are distinct from other indigenous Amerindians with various mtDNA and autosomal DNA (atDNA) mutations. This suggests that the earliest migrants into the northern extremes of North America and Greenland derived from later migrant populations.
Land bridge theory
Also known as the Bering Strait Theory or Beringia theory, the Land Bridge theory has been widely accepted since the 1930s. The idea was first postulated in a rudimentary fashion in 1590 by the Jesuit scholar José de Acosta. This model of migration into the New World proposes that people migrated 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 metres (200 ft) 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 (1,600 km) wide existed between Siberia and the western coast of Alaska. In the "short chronology" version, from the archaeological evidence gathered, it was concluded that this culture of big game hunters crossed the Bering Strait at least 12,000 years ago and could have eventually reached the southern tip of South America by 11,000 years ago.
Crossings by foot of the Bering Sea, however, are also possible when the sea is frozen.
At some point during 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 language families, a movement of tribes along the Rocky Mountain foothills and eastward across the Great Plains to the Atlantic seaboard is assumed to have occurred at least some 13,000 to 10,000 years ago.
This big game-hunting culture has been labeled the Clovis culture, and is primarily identified by its artifacts of fluted projectile points. The culture received its name from artifacts found near Clovis, New Mexico, the first evidence of this tool complex, excavated in 1932. The Clovis culture ranged over much of North America and appeared in South America. The culture is identified by a distinctive Clovis point, a flaked flint spear-point with a notched flute by which it was inserted into a shaft. It could be removed from the shaft for traveling. This flute is one characteristic that defines the Clovis point complex.
Dating Clovis materials has been by association with animal bones and by carbon dating. Recent reexaminations of Clovis materials using improved carbon-dating methods produced results of 11,050 and 10,800 radiocarbon years B.P. (before present). This evidence suggests that the culture flowered somewhat later and for a shorter period of time than previously believed. Michael R. Waters of Texas A&M University in College Station and Thomas W. Stafford Jr., proprietor of a private-sector laboratory in Lafayette, Colorado and an expert in radiocarbon dating, attempted to determine the dates of the Clovis period. The heyday of Clovis technology has typically been set between 11,500 and 10,900 radiocarbon years B.P. (The radiocarbon calibration is disputed for this period, but the widely used IntCal04 calibration puts the dates at 13,300 to 12,800 calendar years B.P.). In a controversial move, Waters and Stafford conclude that no fewer than 11 of the 22 Clovis sites with radiocarbon dates are "problematic" and should be disregarded—including the type site in Clovis, New Mexico. They argue that the datable samples could have been contaminated by earlier material. This contention was considered highly controversial by many in the archaeological community.
In 2014, the autosomal DNA of a 12,500+-year-old infant from Montana was sequenced. The DNA was taken from a skeleton referred to as Anzick-1, found in close association with several Clovis artifacts. Comparisons showed strong affinities with DNA from Siberian sites, and virtually ruled out any close affinity with European sources (the so-called "Solutrean hypothesis"). The DNA also showed strong affinities with all existing Native American populations, which indicated that all of them derive from an ancient population that lived in or near Siberia, the Upper Palaeolithic Mal'ta population. The data indicate that Anzick-1 is from a population directly ancestral to present South American and Central American Native American populations, ruling out hypotheses which posit that invasions subsequent to the Clovis culture overwhelmed or assimilated previous migrants into the Americas. Anzick-1 is less closely related to present North American Native American populations, suggesting an early divergence between North American and Central plus South American populations, with the North American populations being basal to the rest.
Problems with Clovis migration models
Significant problems arise with the Clovis migration model. If Clovis people radiated south after entering the New World and eventually reached 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. They concluded that the radiocarbon evidence predates Clovis sites in the North American Midwest by at least 1,000 years. This supports the theory of a primary coastal migration route people used to move south along the coastline faster than those who migrated inland into the central areas of the Americas. Many excavations have uncovered evidence that subsistence patterns of early Americans included foods such as turtles, shellfish, and tubers. This is 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 the Topper archaeological site (located along the banks of the Savannah River near Allendale, South Carolina) investigated by University of South Carolina archaeologist Dr. Albert Goodyear, charcoal material recovered in association with purported human artifacts returned radiocarbon dates of up to 50,000 years before the present (BP). This would indicate the presence of humans well before the last glacial period. Considerable doubt over the validity of these findings has been raised by many other researchers, and the pre-Clovis Topper dates remain controversial. Charcoal could have originated from forest fires, and the crude stone artifacts may be misinterpreted geofacts.
Pre-Clovis dates have been claimed for several sites in South America, but these early dates have not been verified unequivocally.
Discoveries in 2002 and 2003 of human coprolites (fossilized feces) as well as hunting tools found deeply buried in the Paisley Caves in Oregon indicate the presence of humans in North America as much as 1,200 years prior to the Clovis culture.
Watercraft migration theories
Earlier finds have led to a pre-Clovis culture theory encompassing different migration models with an expanded chronology to supersede the "Clovis-first" theory.
Pacific coastal models
Pacific models propose that people first reached the Americas via water travel, following coastlines from northeast Asia into the Americas. Coastlines are unusually productive environments because they provide humans with access to a diverse array of plants and animals from both terrestrial and marine ecosystems. While not exclusive of land-based migrations, the Pacific 'coastal migration theory' helps explain how early colonists reached areas extremely distant from the Bering Strait region, including sites such as Monte Verde in southern Chile and Taima-Taima in western Venezuela. Two cultural components were discovered at Monte Verde near the Pacific Coast of Chile. The youngest layer is radiocarbon dated at 12,500 radiocarbon years (~14,000 cal BP) and has produced the remains of several types of seaweeds collected from coastal habitats. The older and more controversial component may date back as far as 33,000 years, but few scholars currently accept this very early component.
Other coastal models, dealing specifically with the peopling of the Pacific Northwest and California coasts, have been advocated by archaeologists Knut Fladmark, Roy Carlson, James Dixon, Jon Erlandson, Ruth Gruhn, and Daryl Fedje. In a 2007 article in the Journal of Island and Coastal Archaeology, Erlandson and his colleagues proposed a corollary to the coastal migration theory—the "kelp highway hypothesis"—arguing that productive kelp forests supporting similar suites of plants and animals would have existed near the end of the Pleistocene around much of the Pacific Rim from Japan to Beringia, the Pacific Northwest, and California, as well as the Andean Coast of South America. Once the coastlines of Alaska and British Columbia had deglaciated about 16,000 years ago, these kelp forest (along with estuarine, mangrove, and coral reef) habitats would have provided an ecologically similar migration corridor, entirely at sea level, and essentially unobstructed.
East Asians: Paleoindians of the coast
The boat-builders from Southeast Asia may have been one of the earliest groups to reach the shores of North America. One theory suggests people in boats followed the coastline from the Kurile Islands to Alaska down the coasts of North and South America as far as Chile [2 62; 7 54, 57]. The Haida nation on the Queen Charlotte Islands off the coast of British Columbia may have originated from these early Asian mariners between 25,000 and 12,000. Early watercraft migration would also explain the habitation of coastal sites in South America such as Pikimachay Cave in Peru by 20,000 years ago and Monte Verde in Chile by 13,000 years ago [6 30; 8 383].
- "'There was boat use in Japan 20,000 years ago,' says Jon Erlandson, a University of Oregon anthropologist. 'The Kurile Islands (north of Japan) are like stepping stones to Beringia,' the then continuous land bridging the Bering Strait. Migrants, he said, could have then skirted the tidewater glaciers in Canada right on down the coast." [7 64]'
Atlantic coastal model
Archaeologists Dennis Stanford and Bruce Bradley champion the coastal Atlantic route. Their Solutrean Hypothesis is also based on evidence from the Clovis complex, but instead traces the origins of the Clovis toolmaking style to the Solutrean culture of Ice Age Western Europe. The theory suggests that early European people (or peoples) may have been among the earliest settlers of the Americas. Citing evidence that the Solutrean culture of prehistoric Europe may have provided the basis for the tool-making of the Clovis culture in the Americas, the theory suggests that Ice Age Europeans migrated to North America by using skills similar to those possessed by the modern Inuit peoples and followed the edge of the ice sheet that spanned the Atlantic. The hypothesis rests upon particular similarities in Solutrean and Clovis technology that have no known counterparts in Eastern Asia, Siberia or Beringia, areas from which, or through which, early Americans are known to have migrated. Most professionals discount the theory for a variety of reasons—including the fact that the differences between the two tool-making traditions far outweigh the similarities, the several thousand miles of the Atlantic Ocean they would have had to cross, and the 5,000-year-span that separates the two cultures. Genetic studies of Native American populations have also shown that the Solutrean theory is unlikely, showing instead that the five main mtDNA haplogroups found in the Americas were all part of one gene pool migration from Asia.
Problems with evaluating coastal migration models
The coastal migration models provide a different perspective on migration to the New World, but they are not without their own problems. One of the biggest problems is that global sea levels have risen over 100 metres since the end of the last glacial period, and this has submerged the ancient coastlines that maritime people would have followed into the Americas. Finding sites associated with early coastal migrations is extremely difficult—and systematic excavation of any sites found in deeper waters is challenging and expensive. On the other hand, there is evidence of marine technologies found in the hills of California's Channel Islands, circa 10,000 BCE. If there was an early pre-Clovis coastal migration, there is always the possibility of a "failed colonization". Another problem that arises is the lack of hard evidence found for a "long chronology" theory. No sites have yet produced a consistent chronology older than about 12,500 radiocarbon years (~14,500 calendar years), but research has been limited in South America related to the possibility of early coastal migrations.
Notes and references
- Goebel, Ted; Waters, Michael R.; O'Rourke, Dennis H. (2008). "The Late Pleistocene dispersal of modern humans in the Americas" (PDF). Science 319 (5869): 1497–1502. doi:10.1126/science.1153569. PMID 18339930. Retrieved 2010-02-05.
- "Pause Is Seen in a Continent’s Peopling". New York Times. 13 Mar 2014.
- Gremillion, David H. (2008-09-25). Archaeolog: Pre Siberian Human Migration to America: Possible validation by HTLV-1 mutation analysis. Traumwerk.stanford.edu. doi:10.1371/journal.pgen.1000078. Retrieved 2010-10-12.
- Bonatto, Sandro L.; Salzano, Francisco M. (1997). "A single and early migration for the peopling of the Americas supported by mitochondrial DNA sequence data". Proceedings of the National Academy of Sciences 94: 1866–1871. doi:10.1073/pnas.94.5.1866. PMC 20009. PMID 9050871.
- Phillip M. White (2006). American Indian chronology: chronologies of the American mosaic. Greenwood Publishing Group. p. 1. ISBN 978-0-313-33820-5. Retrieved 29 November 2011.
- Wells, Spencer; Read, Mark (2002). The Journey of Man - A Genetic Odyssey (Digitised online by Google books). Random House. pp. 138–140. ISBN 0-8129-7146-9. Retrieved 2009-11-21.
- "Chaw joins poop in archaeology arsenal". University of Wisconsin.
- Axelrod, Alan (2003). The Complete Idiot's Guide to American History. Alpha Books. ISBN 0-02-864464-6. Retrieved 2010-02-05.
- "Introduction". Government of Canada. Parks Canada. 2009. Retrieved 2010-01-09. "Canada's oldest known home is a cave in Yukon occupied not 12,000 years ago like the U.S. sites, but at least 20,000 years ago"
- "Pleistocene Archaeology of the Old Crow Flats". Vuntut National Park of Canada. 2008. Retrieved 2010-01-10. "However, despite the lack of this conclusive and widespread evidence, there are suggestions of human occupation in the northern Yukon about 24,000 years ago, and hints of the presence of humans in the Old Crow Basin as far back as about 40,000 years ago."[dead link]
- "Atlas of the Human Journey". National Genographic.
- "First Americans". Southern Methodist University-David J. Meltzer, B.A., M.A., Ph.D. Archived from the original on 2009-11-01.
- "Jorney of mankind". Brad Shaw Foundation.
- Lister, Adrian; Bahn, Paul G (2007-11-10). "Mammoths: Giants of the Ice Age". By Adrian Lister, Paul G. Bahn. ISBN 978-0-7112-2801-6.
- Jordan, David K (2009). "Prehistoric Beringia". University of California-San Diego. Retrieved 2010-04-15.
- 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)
- "Beringian Standstill and Spread of Native American Founders". PLoS ONE (eISSN-1932-6203).
- Than, Ker (2008). "New World Settlers Took 20,000-Year Pit Stop". National Geographic Society. Retrieved 2010-01-23. "Over time descendants developed a unique culture—one that was different from the original migrants' way of life in Asia but which contained seeds of the new cultures that would eventually appear throughout the Americas"
- "The peopling of the Americas: Genetic ancestry influences health". Scientific American.
- "First Americans Endured 20,000-Year Layover - Jennifer Viegas, Discovery News". Retrieved 2009-10-05.
- (2003) "Y-Chromosome Evidence for Differing Ancient Demographic Histories in the Americas," (pdf) Maria-Catira Bortolini, Francisco M. Salzano, Mark G. Thomas, Steven Stuart, Selja P. K. Nasanen, Claiton H. D. Bau, Mara H. Hutz, Zulay Layrisse, Maria L. Petzl-Erler, Luiza T. Tsuneto, Kim Hill, Ana M. Hurtado, Dinorah Castro-de-Guerra, Maria M. Torres, Helena Groot, Roman Michalski, Pagbajabyn Nymadawa, Gabriel Bedoya, Neil Bradman, Damian Labuda, Andres Ruiz-Linares. Department of Biology, University College, London; Departamento de Genética, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil; Instituto Venezolano de Investigaciones Científicas, Caracas, Venezuela; Departamento de Genética, Universidade Federal do Paraná, Curitiba, Brazil; 5Department of Anthropology, University of New Mexico, Albuquerque; 6Laboratorio de Genética Humana, Universidad de los Andes, Bogotá; Victoria Hospital, Prince Albert, Canada; Subassembly of Medical Sciences, Mongolian Academy of Sciences, Ulaanbaatar, Mongolia; Laboratorio de Genética Molecular, Facultad de Medicina, Universidad de Antioquia, Medellín, Colombia; Université de Montréal, Montreal. 73:524-539. Retrieved 2010-01-22.
- Dyke, A.S., A. Moore, and L. Robertson, 2003, Deglaciation of North America, Geological Survey of Canada Open File, 1574. (Thirty-two digital maps at 1:7,000,000 scale with accompanying digital chronological database and one poster (two sheets) with full map series.)
- "First Americans Endured 20,000-Year Layover - Jennifer Viegas, Discovery News". Retrieved 2009-11-18. "Archaeological evidence, in fact, recognizes that people started to leave Beringia for the New World around 40,000 years ago, but rapid expansion into North America didn't occur until about 15,000 years ago, when the ice had literally broken" page 2
- Linda Crawford Culberson (2009). Arrowheads and Spear Points in the Prehistoric Southeast: A Guide to Understanding Cultural Artifacts. Univ. Press of Mississippi. pp. 40–44. ISBN 978-1-60473-485-0.
- Terry L. Jones; Kathryn Klar; Society for California Archaeology (2007). California Prehistory: Colonization, Culture, and Complexity. Rowman Altamira. p. 62. ISBN 978-0-7591-0872-1.
- Norman Herz; Ervan G. Garrison (1998). Geological methods for archaeology. Oxford University Press. p. 125. ISBN 978-0-19-509024-6.
- Robert Andrew Foley; Roger Lewin (2013). Principles of Human Evolution. John Wiley & Sons. p. 663. ISBN 978-1-118-68799-4.
- "Palaeo-Indian archaeology". Canadian Studies Program, Canadian Heritage.
- C. Michael Barton (2004). The Settlement of the American Continents: A Multidisciplinary Approach to Human Biogeography. University of Arizona Press. p. 72. ISBN 978-0-8165-2323-8.
- "The Topper Site in South Carolina". Ohio Archaeological Inventor.
- Gibbon, Guy E; Ames, Kenneth M (1998). "Archaeology of Prehistoric Native America: An Encyclopedia". By Guy E. Gibbon, Kenneth M. Ames (1998). ISBN 978-0-8153-0725-9.
- Peter N. Jones (2005). Respect for the Ancestors: American Indian Cultural Affiliation in the American West. Bauu Institute. p. 52. ISBN 978-0-9721349-2-7.
- Dickason, Olive. Canada's First Nations: A History of the Founding Peoples from the Earliest Times. 2nd edition. Toronto: Oxford University Press, 1997.
- "Alberta History pre 1800 - Jasper Alberta". AlbertaJasper.com.
- "pre glaciology in Alberta". Calgary university.
- "An mtDNA view of the peopling of the world by Homo sapiens". Cambridge DNA Services. 2007. Retrieved 2011-06-01.
- Richmond, G.M., Fullerton, D.S. (1986). "Summation of Quaternary glaciations in the United States of America". Quaternary Science Reviews 5: 183–196. doi:10.1016/0277-3791(86)90184-8.
- Tamm E, Kivisild T, Reidla M, et al. (2007). "Beringian Standstill and Spread of Native American Founders". PLoS ONE 2 (9): e829. doi:10.1371/journal.pone.0000829. PMC 1952074. PMID 17786201.
- "Beginnings to 1500 C.E.". Encyclopedia of Canada's Peoples.
- Fagundes, Nelson J.R.; Ricardo Kanitz, Roberta Eckert, Ana C.S. Valls, Mauricio R. Bogo, Francisco M. Salzano, David Glenn Smith, Wilson A. Silva, Marco A. Zago, Andrea K. Ribeiro-dos-Santos, Sidney E.B. Santos, Maria Luiza Petzl-Erler, and Sandro L. Bonatto (2008). "Mitochondrial Population Genomics Supports a Single Pre-Clovis Origin with a Coastal Route for the Peopling of the Americas". American Journal of Human Genetics 82 (3): 583–592. doi:10.1016/j.ajhg.2007.11.013. PMC 2427228. PMID 18313026.
- "Vertebrate paleontology and the alleged ice-free corridor: The meat of the matter". ScienceDirect a registered trademark of Elsevier B.V.
- # Martin, Paul S. (2005): Twilight of the mammoths: Ice Age extinctions and the rewilding of America. University of California Press, Berkeley. ISBN 0-520-23141-4
- Fiedal, Stuart (2009). "Sudden Deaths: The Chronology of Terminal Pleistocene Megafaunal Extinction". In Haynes, Gary. American Megafaunal Extinctions at the End of the Pleistocene. Springer. pp. 21–37. doi:10.1007/978-1-4020-8793-6_2. ISBN 978-1-4020-8792-9.
- "Meadowcroft Rockshelter, Pennsylvania.". Bradshaw Foundation.
- "Chilean Field Yields New Clues to Peopling of Americas". The New York Times. By John Noble Wilford.
- "Cactus Hill Update". Archaeological Institute of America.
- "Taimataima site". Dr. José R. Oliver.
- Connor, Steve (3 December 2002). "Does skull prove that the first Americans came from Europe?". The Independent (London). Retrieved 23 June 2011.
- George Weber. "Tibito and El Abra sites (Colombia )". The Andaman Association.
- "Evidence Supports Earlier Date for People in North America". New York Times. 2008-04-04. Retrieved 2010-05-13.
- Ruhlen M (November 1998). "The origin of the Na-Dene". Proceedings of the National Academy of Sciences of the United States of America 95 (23): 13994–6. doi:10.1073/pnas.95.23.13994. PMC 25007. PMID 9811914.
- William Brandon (2012). The Rise and Fall of North American Indians: From Prehistory through Geronimo. Roberts Rinehart. p. 9. ISBN 978-1-57098-453-2.
- "Worldwide glacier retreat". RealClimate.
- "First Americans". National Geographic society.
- C.J. Heusser (2003). Ice Age Southern Andes: A Chronicle of Palaeoecological Events. Elsevier. p. 80. ISBN 978-0-08-053438-1.
- "Early North American Cultures". Minnesota State University.
- "Debert Palaeo-Indian Site". Nova Scotia Museum.
- "Lagoa Santa sites (Minas Gerais, Brazil)". Andaman Association.
- "Oldest North American Mummy". Archaeological Institute of America.
- "On Your Knees Cave". Timothy H. Heaton. The University of South Dakota. 2002. Retrieved 2009-11-21. "The American Journal of Physical Anthropolog reports new DNA-based research that 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. 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 showed that mtDNA (human mitochondrial DNA) from indigenous populations in coastal British Columbia showed similarities to coastal populations in Southern California, while inland populations in both localities differed markedly. Dates of 9,730 and 9,880 years BP were obtained on the human remains, making them the oldest ever found in Alaska or Canada. The associated bone tool was dated to 10,300 years old"
- Custred, Glynn (2000). "The Forbidden Discovery of Kennewick Man". Academic Questions 13 (3): 12–30. doi:10.1007/s12129-000-1034-8.
- "America: 8000 to 5000 B.C.". Rice University.
- Bronowski, Jacob (1975). The Ascent of Man. British Broadcasting Corporation. pp. 92–94. ISBN 0-563-10498-8.
- "Learn about Y-DNA Haplogroup Q. Genebase Tutorials" (Verbal tutorial possible). Genebase Systems. 2008. Retrieved 2009-11-21.
- Orgel L (2004). "Prebiotic chemistry and the origin of the RNA world" (PDF). Crit Rev Biochem Mol Biol 39 (2): 99–123. doi:10.1080/10409230490460765. PMID 15217990. Retrieved 2010-01-19.
- "Summary of knowledge on the subclades of Haplogroup Q". Genebase Systems. 2009. Retrieved 2009-11-22.
- Zegura SL, Karafet TM, Zhivotovsky LA, Hammer MF (January 2004). "High-resolution SNPs and microsatellite haplotypes point to a single, recent entry of Native American Y chromosomes into the Americas". Molecular Biology and Evolution 21 (1): 164–75. doi:10.1093/molbev/msh009. PMID 14595095.
- "mtDNA Variation among Greenland Eskimos. The Edge of the Beringian Expansion". Laboratory of Biological Anthropology, Institute of Forensic Medicine, University of Copenhagen, Copenhagen, McDonald Institute for Archaeological Research,University of Cambridge, Cambridge, University of Hamburg, Hamburg. 2000. doi:10.1086/303038. Retrieved 2009-11-22.
- "The peopling of the New World - Perspectives from Molecular Anthropology". Department of Anthropology, University of Pennsylvania (Annual Review of Anthropology): Vol. 33, 551–583. 2004. doi:10.1146/annurev.anthro.33.070203.143932. Retrieved 2010-02-03.
- "Native American Mitochondrial DNA Analysis Indicates That the Amerind and the Nadene Populations Were Founded by Two Independent Migrations". Center for Genetics and Molecular Medicine and Departments of Biochemistry and Anthropology, Emory University School of Medicine, Atlanta, Georgia. Genetics Society of America. Vol 130, 153-162. Retrieved 2009-11-28.
- Charles C. Mann (2006), 1491: new revelations of the Americas before Columbus, Random House Digital, p. 143, ISBN 978-1-4000-3205-1
- "Epic explorer crosses frozen sea". BBC News. 2006-04-03.
- Raff, J. A.; Bolnick, D. A. (2014-02-13). "Palaeogenomics: Genetic roots of the first Americans". Nature 506 (7487): 162–163. doi:10.1038/506162a.
- Callaway, E. (2014-02-12). "Ancient genome stirs ethics debate". Nature 506 (7487): 142–143. doi:10.1038/506142a.
- Watson, T. (2014-02-13). "New theories shine light on origins of Native Americans". USA Today web site. Gannett Company. Retrieved 2014-02-15.
- Rasmussen, M.; Anzick, S. L.; Waters, M. R.; Skoglund, P.; DeGiorgio, M.; Stafford, T. W.; Rasmussen, S.; Moltke, I.; Albrechtsen, A.; Doyle, S. M.; Poznik, G. D.; Gudmundsdottir, V.; Yadav, R.; Malaspinas, A. S.; White, S. S.; Allentoft, M. E.; Cornejo, O. E.; Tambets, K.; Eriksson, A.; Heintzman, P. D.; Karmin, M.; Korneliussen, T. S.; Meltzer, D. J.; Pierre, T. L.; Stenderup, J.; Saag, L.; Warmuth, V. M.; Lopes, M. C.; Malhi, R. S.; Brunak, S. R.; Sicheritz-Ponten, T.; Barnes, I.; Collins, M.; Orlando, L.; Balloux, F.; Manica, A.; Gupta, R.; Metspalu, M.; Bustamante, C. D.; Jakobsson, M.; Nielsen, R.; Willerslev, E. (2014-02-13). "The genome of a Late Pleistocene human from a Clovis burial site in western Montana". Nature 506 (7487): 225–229. doi:10.1038/nature13025. PMID 24522598.
- Diamond, Jared M. (1991). The Rise and Fall of the Third Chimpanzee. Radius. p. 308. ISBN 978-0-09-174268-3. OCLC 21594215.
- Dillehay, Thomas (2000). The Settlement of the Americas: A New Prehistory. New York: Basic Books. ISBN 0-465-07669-6.
- "Faeces hint at first Americans". BBC. April 3, 2008. Retrieved October 21, 2011.
- Jenkins / Willerslev et al. "Clovis Age Western Stemmed Projectile Points and Human Coprolites at the Paisley Caves" Science (Magazine), 13 July 2012. Retrieved: 13 July 2012.
- Wilford, John Noble. "Spearheads and DNA Point to a Second Founding Society in North America" New York Times, 12 July 2012. Retrieved: 13 July 2012.
- Thomas H. Maugh II. "Who lived here first? New info on North America's earliest residents" Los Angeles Times, 12 July 2012. Retrieved: 13 July 2012.
- Joseph F. Powell (November 14, 2005), The first Americans: race, evolution, and the origin of Native Americans, Cambridge University Press, p. 123, ISBN 978-0-521-82350-0
- Bruce Bradley; Dennis Stanford (2004). "The North Atlantic ice-edge corridor: a possible Palaeolithic route to the New World". World Archaeology. 36(4): 459–478. doi:10.1080/0043824042000303656.
- Carey, Bjorn (2006-02-19). "First Americans may have been European". Life Science.com. Retrieved 2010-10-13.
- Lawrence Guy Straus; David J. Meltzer; Ted Goebel, Ice Age Atlantis? Exploring the Solutrean-Clovis ‘connection’, retrieved 2011-04-24, "Bradley and Stanford (2004) have raised now, in several instances, the claim that European Upper Paleolithic Solutrean peoples colonized North America, and gave rise to the archaeological complex known as Clovis. They do so in the face of some obvious challenges—notably the several thousand miles of ocean and the 5000 radiocarbon years that separate the two. And yet they argue in their recent paper that the archaeological evidence in support of a historical connection is ‘overwhelming’. We are profoundly skeptical of this claim; we believe that the many diﬀerences between Solutrean and Clovis are far more significant than the few similarities, the latter being readily explained by the well-known phenomenon of technological convergence or parallelism. The origin and arrival time of the ﬁrst Americans remain uncertain, but not so uncertain that we need to look elsewhere other than north-east Asia."
- Carl Waldman. ATLAS OF THE NORTH AMERICAN INDIAN (3 ed.). Facts on File, Inc. p. 2. ISBN 978-0-8160-6858-6.
- Nelson J.R. Fagundes; Ricardo Kanitz; Roberta Eckert; Ana C.S. Valls; Mauricio R. Bogo; Francisco M. Salzano; David Glenn Smith; Wilson A. Silva Jr.; Marco A. Zago; Andrea K. Ribeiro-dos-Santos; Sidney E.B. Santos; Maria Luiza Petzl-Erler (2008-03-03), Mitochondrial Population Genomics Supports a Single Pre-Clovis Origin with a Coastal Route for the Peopling of the Americas, Elsevier, doi:10.1016/j.ajhg.2007.11.013, PMC 2427228, PMID 18313026, retrieved 2011-04-24, "Our results strongly support the hypothesis that haplogroup X, together with the other four main mtDNA haplogroups, was part of the gene pool of a single Native American founding population; therefore they do not support models that propose haplogroup-independent migrations, such as the migration from Europe posed by the Solutrean hypothesis."
- "California islands give up evidence of early seafaring: Numerous artifacts found at late Pleistocene sites on the Channel Islands," ScienceDaily, March 4, 2011. http://www.sciencedaily.com/releases/2011/03/110303141540.htm
- Jared Diamond, Guns, germs and steel. A short history of everybody for the last 13'000 years, 1997.
- Dixon, E. James. Quest for the Origins of the First Americans. University of New Mexico Press. 1993.
- Dixon, E. James. Bones, Boats, and Bison: the Early Archeology of Western North America. University of New Mexico Press. 1993.
- Erlandson, Jon M. Early Hunter-Gatherers of the California Coast. Plenum Press. 1994.
- Erlandson, Jon M. The Archaeology of Aquatic Adaptations: Paradigms for a New Millennium. Journal of Archaeological Research, Vo. 9, 2001. pp. 287–350.
- Erlandson, Jon M. Anatomically Modern Humans, Maritime Migrations, and the Peopling of the New World. In The First Americans: The Pleistocene Colonization of the New World, edited by N. Jablonski, 2002. pp. 59–92. Memoirs of the California Academy of Sciences. San Francisco.
- Erlandson, Jon. M., M. H. Graham, Bruce J. Bourque, Debra Corbett, James A. Estes, & R. S. Steneck. The Kelp Highway Hypothesis: Marine Ecology, The Coastal Migration Theory, and the Peopling of the Americas. Journal of Island and Coastal Archaeology, Vo. 2, 2007. pp. 161–174.
- 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)
- Fedje, & Christensen. Modeling Paleoshorelines and Locating Early Holocene Coastal Sites in Haida Gwaii. American Antiquity, Vol. 64, #4, 1999. pp. 635–652.
- E. F. Greenman, "The Upper Palaeolithic and the New World", Current Anthropology, 4: 41–66 (1963)
- 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).
- Jones, Peter N. Respect for the Ancestors: American Indian Cultural Affiliation in the American West. Bauu Institute Press. 2005.
- Matson and Coupland. The Prehistory of the Northwest Coast. Academic Press. New York. 1995.
- Adovasio, J. M., with Jake Page. The First Americans: In Pursuit of Archaeology's Greatest Mystery. New York: Random House, 2002.
- Bradley, B.; Stanford, D. "The North Atlantic ice-edge corridor: a possible Palaeolithic route to the New World". World Archaeology 36 (4): 2004. doi:10.1080/0043824042000303656.
- Bradley, B.; Stanford, D. "The Solutrean-Clovisct=result connection: reply to Straus, Meltzer and Goebel". World Archaeology 38. JSTOR 40024066.
- 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.
- Jones, Peter N. "Respect for the Ancestors: American Indian Cultural Affiliation in the American West." Boulder, Colorado: Bauu Press. 2004
- Dixon, E. James. Bones, Boats and Bison: the Early Archeology of Western North America. University of New Mexico Press. 1999.
- Evidence Supports Earlier Date for People in North America, April 4, 2008
- Dennis J. Stanford, Bruce Bradely, Pre-Clovis First Americans: The Origin of America's Clovis Culture (University of California Press, 2012). ISBN 978-0-520-22783-5
- Dennis J. Stanford, Bruce A. Bradley, Across Atlantic Ice: The Origin of America's Clovis Culture (University of California Press (2012). ISBN 978-0-520-22783-5
- First peoples in a new world: colonizing ice age America - by David J Meltzer - University of California, Berkeley, 2009 ISBN 0-520-25052-4
- The First Americans: The Pleistocene Colonization of the New World - by Nina G. Jablonski - California Academy of Sciences, 2002 ISBN 0-940228-49-1
- Journey of Man: A Genetic Odyssey (book) - by Spencer Wells - Princeton University Press, 2002 ISBN 0-8129-7146-9
- Early human migrations
- Origins of Paleoindians
- Dené–Yeniseian languages, a proposed family of languages that are spoken by indigenous peoples of Asia and North America
- Historical migration
- History of Mesoamerica (Paleo-Indian)
- Paleo-Indians period (Canada)
- Norse colonization of the Americas
- Olmec alternative origin speculations
- Recent African origin of modern humans
- Pre-Columbian trans-oceanic contact
- List of countries and islands by first human settlement
|Wikimedia Commons has media related to Indigenous nations of the Americas.|
- "When Did Humans Come to the Americas?" - Smithsonian Magazine February 2013
- Journey of Man: A Genetic Odyssey (movie) on YouTube - by Spencer Wells - PBS and National Geographic Channel, 2003 - 120 Minutes, UPC/EAN: 841887001267
- Atlas of the Human Journey, Genographic Project, National Geographic
- An mtDNA view of the peopling of the world by Homo sapiens Cambridge DNA's
- Journey of Mankind - Genetic Map – Bradshaw Foundation
- The Paleoindian Period – United States Department of the Interior, National Park Service
- Alabama Archaeology: Prehistoric Alabama – The University of Alabama, Department of Archaeology
- The Paleoindian Database – The University of Tennessee, Department of Anthropology.
- Paleoindians and the Great Pleistocene Die-Off – American Academy of Arts and Sciences, National Humanities Center