Clovis culture

A Clovis projectile point created using bifacial percussion flaking (that is, each face is flaked on both edges alternately with a percussor)

The Clovis culture (sometimes referred to as the Llano culture^[1]) is a prehistoric Paleo-Indian culture that first appears 11,500 RCYBP (radiocarbon years before present^[2]), at the end of the last glacial period, characterized by the manufacture of "Clovis points" and distinctive bone and ivory tools. Archaeologists' most precise determinations at present suggest that this radiocarbon age is equal to roughly 13,500 to 13,000 calendar years ago.

The Clovis culture was replaced by several more localized regional cultures from the time of the Younger Dryas cold climate period onward. Post-Clovis cultures include the Folsom tradition, Gainey, Suwannee-Simpson, Plainview-Goshen, Cumberland, and Redstone. Each of these is commonly thought to derive directly from Clovis, in some cases apparently differing only in the length of the fluting on their projectile points. Although this is generally held to be the result of normal cultural change through time,^[3] numerous other reasons have been suggested to be the driving force for the observed changes in the archaeological record, such as an extraterrestrial impact event or post-glacial climate change with numerous faunal extinctions.

After the discovery of several Clovis sites in western North America in the 1930s, the Clovis people came to be regarded as the first human inhabitants of the New World. Clovis people were considered to be the ancestors of all the indigenous cultures of North and South America. However, this majority view has been contested over the last thirty years^[when?] by several archaeological discoveries, including possible sites like Cactus Hill in Virginia, Paisley Caves in the Summer Lake Basin of Oregon, the Topper site in Allendale County, South Carolina, Meadowcroft Rockshelter in Pennsylvania, the Friedkin^[4] site in Texas, and the Monte Verde^[5] and Cueva Fell sites in Chile. The claim to the oldest human archaeological site known in the Americas belongs to the Pedra Furada human remains and hearths, a site that precedes the Clovis culture and the other sites already mentioned by 19,000 to 30,000 years, but this discovery has become an issue of contention between North American archaeologists and their South American and European counterparts.^[6][7][8] In American archaeology most dates older than 10,000 are controversial. They are under intense scrutiny and may change as new dating technologies are developed and existing ones refined.^[9]

Description

Clovis points from the Rummells-Maske Cache Site, Iowa.

The culture was originally named for a small number of artifacts found between 1936 and 1938 at Blackwater Locality No. 1, an archaeological site near Clovis, New Mexico. People began collecting artifacts at this site in the late 1920s but artifacts and animal remains that had not moved since the Pleistocene were not recovered until 1936. The in situ finds of 1936 and 1937 included most of four stone Clovis points, two long bone points with impact damage, stone blades, a portion of a Clovis blade core, and several cutting tools made on stone flakes. Clovis sites have since been identified throughout much, but not all, of the contiguous United States, as well as Mexico and Central America, and even into Northern South America.^[10]

A hallmark of the toolkit associated with the Clovis culture is the distinctively shaped, fluted stone spear point, known as the Clovis point. The Clovis point is bifacial and typically fluted on both sides. Archaeologists do not agree on whether the widespread presence of these artifacts indicates the proliferation of a single people, or the adoption of a superior technology by diverse population groups. It is generally accepted that Clovis people hunted mammoth as Clovis points have repeatedly been found in sites containing mammoth remains. Mammoth was only a small part of the Clovis diet; extinct bison, mastodon, sloths, tapir, palaeolama, horse (the association of Clovis with horse remains is in dispute as no actual Clovis artifacts have been found in direct association with fossil horse remains) and a host of smaller animals have also been found in Clovis sites where they were killed and eaten. In total, more than 125 species of plants and animals are known to have been used by Clovis people in the portion of the Western Hemisphere they inhabited.^{[citation needed]}

Disappearance of Clovis

Further information: Younger Dryas

The most commonly held perspective on the end of the Clovis culture is that a decline in the availability of megafauna, combined with an overall increase in a less mobile population, led to local differentiation of lithic and cultural traditions across the Americas.^[3][11] After this time, Clovis-style fluted points were replaced by other fluted-point traditions (such as the Folsom culture) with an essentially uninterrupted sequence across North and Central America. An effectively continuous cultural adaptation proceeds from the Clovis period through the ensuing Middle and Late Paleoindian periods.^[12] It has also been argued that Clovis ended in a very abrupt fashion.

Whether the Clovis culture drove the mammoth, and other species, to extinction via overhunting – the so-called Pleistocene overkill hypothesis – is still an open, and controversial, question. It has also been hypothesized that the Clovis culture saw its decline in the wake of the Younger Dryas cold phase. This 'cold shock', lasting roughly 1,500 years, affected many parts of the world, including North America. It appears to have been triggered by a vast meltwater lake – Lake Agassiz – emptying into the North Atlantic, disrupting the thermohaline circulation.

A recent hypothesis suggests that one or more extraterrestrial bodies caused the mass extinction and triggered a period of climatic cooling.^[13] This is known as the Clovis Comet or the Younger Dryas impact hypothesis and proposes that an extraterrestrial object such as a comet exploded in Earth's atmosphere above North America's Great Lakes region about 12,900 years ago,^[14] and significantly impacted the human Clovis culture. Research published in January 2009 argues that there was no extraterrestrial impact but fails to explain the high levels of metal and magnetic spherules found deep inside the tusks and skulls of mammoths.^[15] Additional possible evidence of comet impact is the widespread occurrence of microdiamonds and black mats in a layer of sedimentary rocks of that era,^[16] but is not reflected in the extinction record.

Discovery

Main article: Burnet Cave

A cowboy and former slave, George McJunkin, found an Ancient Bison (Bison antiquus, an extinct relative of the American Bison) skeleton in 1908 after a flash flood.^[17] It was first excavated in 1926, near Folsom, New Mexico under the direction of Harold Cook and Jesse Figgins. On August 29, 1927 they found the first in situ Folsom point with the extinct B. antiquus bones. This confirmation of a human presence in the Americas during the Pleistocene inspired many people to start looking for evidence of Early Man.^[18]

In 1929, 19-year-old Ridgely Whiteman, who had been closely following the excavations in nearby Folsom in the newspaper, discovered the Clovis Man Site in the Blackwater Draw in Eastern New Mexico.^[17] Despite earlier legitimate Paleoindian discoveries^{[citation needed]}, the best documented evidence of the Clovis tool complex was excavated between 1932 and 1937 near Clovis, New Mexico, by a crew under the direction of Edgar Billings Howard from the Academy of Natural Sciences/University of Pennsylvania.^[17] Howard's crew left their excavation in Burnet Cave, New Mexico (truly the first professionally excavated Clovis site^{[citation needed]}) in August, 1932 and visited Whiteman and his Blackwater Draw site. In November, Howard was back at Blackwater Draw to investigate additional finds from a construction project.^[17]

The American Journal of Archaeology (January–March, 1932 V36 #1) in its Archaeological Notes mentions E. B. Howard's work in Burnet Cave, including the discovery of extinct fauna and a "Folsom type" point four feet below a Basketmaker burial. This brief mention of the Clovis point found in place predates any work at Dent, Colorado. Reference is made to a slightly earlier article on Burnet Cave in The University Museum Bulletin of November, 1931.^{[citation needed]}

The first report of professional work at the Blackwater Draw Clovis site is in the November 25, 1932 issue of Science News.^{[citation needed]} The publications on Burnet Cave and Blackwater Draw directly contradict statements by several authors (for example see Haynes 2002:56 The Early Settlement of North America) that Dent, Colorado was the first excavated Clovis site. The Dent Site, in Weld County, Colorado, was simply a fossil mammoth excavation in 1932. The first Dent Clovis point was found November 5, 1932 and the in situ point was found July 7, 1933. The in situ Clovis point from Burnet Cave was excavated in late August, 1931 (and reported early in 1932). E. B. Howard brought the Burnet Cave point to the 3rd Pecos Conference, September 1931, and showed it around to several archaeologists interested in Early Man (see Woodbury 1983)^{[citation needed]}.

Clovis First

Main article: Settlement of the Americas

Known as "Clovis First", the predominant hypothesis among archaeologists in the latter half of the 20th century had been that the people associated with the Clovis culture were the first inhabitants of the Americas. The primary support for this was that no solid evidence of pre-Clovis human inhabitation had been found. According to the standard accepted theory, the Clovis people crossed the Beringia land bridge over the Bering Strait from Siberia to Alaska during the period of lowered sea levels during the ice age, then made their way southward through an ice-free corridor east of the Rocky Mountains in present-day western Canada as the glaciers retreated. This hypothesis has been continuously challenged by studies that suggest a Pre-Clovis Human occupation of the Americas^[19] until in 2011, following the discovery of pre-Clovis occupation site, a prominent group of scientists claimed to have definitely established the existence "of an occupation older than Clovis."^[20][21]

Evidence of human habitation before Clovis

Archaeological sites that predate Clovis that are well documented include the following:

• Pedra Furada, Piauí, Brazil (55,000 yr BP ABOX)^[22][23][24]
• Topper, (50,000 yr BP) South Carolina, US^[25][26]
• Meadowcroft, Pennsylvania, US (16,000 yr BP)^[27]
• Buttermilk Creek Complex, Salado, Texas, US (15,500 ¹⁴C yr BP)^[4][28][29]
• Cactus Hill, Virginia, US (15,000 yr BP) ^[30]
• Saltville, Virginia, US (14,510 ¹⁴C yr BP)^[31]
• Page-Ladson prehistory site, Florida, US (14,500 to 12,500 yr BP)^[32]
• Taima-Taima, Venezuela (14,000 yr BP)^[33]
• Monte Verde, Chile (14,800 ¹⁴C yr BP)^[34][35]
• Tanana Valley, Alaska, US (14,000 yr BP)^[36]
• Paisley Caves, Oregon, US (14,300 yr BP)^[37]
• Lapa do Boquete, Brazil (12,070 ±170 ¹⁴C yr BP)^[34][38]
• Connley Caves, Oregon, US (13,000 yr BP)^[39]
• Nenana valley, Alaska, US (12,000 yr BP)^[40]
• Tibitó, Colombia (11,740 ±110 ¹⁴C yr BP)^[34]
• Tagua-Tagua, Chile (11,380 ±380 ¹⁴C yr BP)^[41]

Predecessors of the Clovis people may have migrated south along the North American coastlines, although there are arguments for many migrations along several different routes.^[42] According to researchers Michael Waters and Thomas Stafford of Texas A&M University, new radiocarbon dates place Clovis remains from the continental United States in a shorter time window (11,050 to 10,900 years ago),^[43] while radiocarbon dating of the Monte Verde site in Chile place Clovis-like culture there as early as 13,500 years ago and remains found at the Channel Islands of California place coastal Paleoindians there 12,500 years ago. This suggests that the Paleoindian migration could have spread more quickly along the Pacific coastline, proceeding south, and that populations that settled along that route could have then begun migrations eastward into the continent.

The Pedra Furada sites in Brazil include a collection of rock shelters, used for thousands of years by diverse human populations. The first excavations yielded artifacts with C14 dates of 48,000 to 32,000 years BP. Repeated analysis has confirmed this dating, carrying the range of dates up to 60,000 BP.^[44] The best analyzed archaeological levels are dated between 32,160 ± 1000 years BP and 17,000 ± 400 BP.

In 2004, worked stone tools were found at Topper in South Carolina that have been dated by radiocarbon techniques possibly to 50,000 years ago,^[45] although there is significant dispute regarding these dates.^[46] Evidence of humans at the Topper Site definitely date back to 22,900 cal yr BP.^[47]

A more substantiated claim is that of Paisley Caves, where rigorous carbon-14 and genetic testing appears to indicate that humans related to modern Native Americans were present in the caves over 1000 ¹⁴C years before the earliest evidence of Clovis. A study published in Science presents strong evidence that humans occupied sites in Monte Verde, at the tip of South America, as early as 13,000 years ago.^[48] If this is true then humans must have entered North America long before the Clovis Culture – perhaps 16,000 years ago.

The Tlapacoya site is located along the base of a volcanic (remnant) hill on the shore of the former Lake Chalco. Seventeen excavations along the base of Tlapacoya hill between 1956 and 1973 uncovered piles of disarticulated bones of bear and deer that appeared to have been butchered, plus 2,500 flakes and blades presumably from the butchering activities, plus one non-fluted spear point. All were found in the same stratum containing three circular hearths filled with charcoal and ash. Bones of many other animal species were also present, including horses and migratory waterfowl. Two uncalibrated radiocarbon dates on carbon from the hearths came in at approximately 24,000 and 22,000 years ago.^[49] At another location a prismatic micro-blade of obsidian was found in association with a tree trunk radiocarbon dated (uncalibrated) at approximately 24,000 years ago. This obsidian blade has recently been hydration dated by Joaquín García-Bárcena to 22,000 years ago and the hydration results published in a seminal article that deals with the evidence for pre-Clovis habitation of Mexico.^[50]

Coastal migration route

Recent studies of the mitochondrial DNA of First Nations/Native Americans suggest that the people of the New World may have diverged genetically from Siberians as early as 20,000 years ago, far earlier than the standard theory suggests.^[19] However, this pattern is not inconsistent with a later colonization from Siberia because gene coalescent theory predicts that genetic co-ancestry is expected to greatly predate colonization and/or isolation. According to one alternative theory, the Pacific coast of North America may have been free of ice, allowing the first peoples in North America to come down this route prior to the formation of the ice-free corridor in the continental interior.^{[citation needed]} No solid evidence has yet been found to support this hypothesis except that genetic analysis of coastal marine life indicates diverse fauna persisting in refugia throughout the Pleistocene ice ages along the coasts of Alaska and British Columbia; these refugia include common food sources of coastal aboriginal peoples, suggesting that a migration along the coastline was feasible at the time.^[51]

Solutrean hypothesis

Main article: Solutrean hypothesis

The controversial Solutrean hypothesis proposed in 1999 by Smithsonian archaeologist Dennis Stanford and colleague Bruce Bradley (Stanford and Bradley 2002), suggests that the Clovis people could have inherited technology from the Solutrean people who lived in southern Europe 21,000-15,000 years ago, and who created the first Stone Age artwork in present-day southern France.^[52] The link is suggested by the similarity in technology between the projectile points of the Solutreans and those of the Clovis people. The model envisions these people making the crossing in small watercraft via the edge of the pack ice in the North Atlantic Ocean that then extended to the Atlantic coast of France, using skills similar to those of the modern Inuit people.

In a 2008 study of the relevant paleoceanographic data, Kieran Westley and Justin Dix concluded that "it is clear from the paleoceanographic and paleo-environmental data that the Last Glacial Maximum (LGM) North Atlantic does not fit the descriptions provided by the proponents of the Solutrean Atlantic Hypothesis. Although ice use and sea mammal hunting may have been important in other contexts, in this instance, the conditions militate against an ice-edge-following, maritime-adapted European population reaching the Americas."^[53]

Supporters^[who?] of this hypothesis suggest that stone tools found at Cactus Hill (an early American site in Virginia), are knapped in a style between Clovis and Solutrean.^{[citation needed]} Other scholars such as Emerson F. Greenman and Remy Cottevieille-Giraudet have also suggested a Northern Atlantic point of entry, citing toolmaking similarities between Clovis and Solutrean-era artifacts.^{[citation needed]}

University of New Mexico anthropologist Lawrence G. Straus, a primary critic of the Solutrean hypothesis, points to the theoretical difficulty of the ocean crossing, a lack of Solutrean-specific features in pre-Clovis artifacts, as well as the lack of art (such as that found at Lascaux in France) among the Clovis people, as major deficiencies in the Solutrean hypothesis. The 3,000 to 5,000 radiocarbon year gap between the Solutrean period of France and Spain and the Clovis of the New World also makes such a connection problematic.^[54] In response, Bradley and Stanford contend that it was "a very specific subset of the Solutrean who formed the parent group that adapted to a maritime environment and eventually made it across the north Atlantic ice-front to colonize the east coast of the Americas" and that this group may not have shared all Solutrean cultural traits.^[55]

Genetic studies

Main article: Indigenous Amerindian genetics

Mitochondrial DNA analysis has found that some members of some native North American tribes have a maternal ancestry (called haplogroup X) linked to the maternal ancestors of some present day individuals in western Asia and Europe, albeit distantly, and has also provided some support for pre-clovis models.

Fagundes et al. in the American Journal of Human Genetics state in their abstract "Here we show, by using 86 complete mitochondrial genomes, that all Native American haplogroups, including haplogroup X, were part of a single founding population, thereby refuting multiple-migration models. A detailed demographic history of the mtDNA sequences estimated with a Bayesian coalescent method indicates a complex model for the peopling of the Americas, in which the initial differentiation from Asian populations ended with a moderate bottleneck in Beringia during the last glacial maximum (LGM), around ∼23,000 to ∼19,000 years ago. Toward the end of the LGM, a strong population expansion started ∼18,000 and finished ∼15,000 years ago. These results support a pre-Clovis occupation of the New World, suggesting a rapid settlement of the continent along a Pacific coastal route." ^[56]

Other sites

In approximate reverse chronological order:

• Pedra Furada, Serra da Capivara National Park, in Piauí, Brazil. Site with evidence of non-Clovis human remains, a rock painting rupestre art drawings from at least 12,000-6,000 BP. Hearth samples C-14 dates of 48-32,000 BP were reported in a Nature article (Guidon and Delibrias 1986). New hearth samples with ABOX dates of 54,000 BP were reported in the Quaternary Science Reviews.^[57] Paleoindian components found here, have been challenged by American researchers as Meltzer, Adovasio, and Dillehay. Niède Guidon is the head archaeologist at the Serra da Capivara National Park.
• Lagoa Santa, Minas Gerais, Brazil, is erroneously asserted to be Clovis age or even possibly Pre-Clovis in age. The recent discussion of this site (specifically Lapa Vermelha IV) and the Luzia skull, reportedly 11,500 years old by Neves and Hubb, makes it clear that this date is a chronological date in years Before Present and not a raw radiocarbon date ^[58] in eastern Brazil. Clovis sites mostly date between 11,500 and 11,000 radiocarbon years which means 13,000 years before present at a minimum. "Luzia" is at least 1,000 years younger than Clovis and Lapa Vermelha IV should not be considered a Pre-Clovis site.
• Cueva del Milodon, in Patagonian Chile^[59] dates at least as early as 10,500 BP. This is a site found particularly early in the New World hunt for Early Man, circa 1896, and needs additional basic research, but 10,500 B. P. would be 1,500 years younger than Clovis, or if the dating is 10,500 RCYBP, it would still be roughly 500–700 years younger than Clovis. In either case this should not be considered a Pre-Clovis site.
• Cueva Fell^[60] and Pali Aike Crater sites in Patagonia, with hearths, stone tools and other elements of human habitation dating to at least as early as 11,000 BP.
• The Big Eddy Site in southwestern Missouri contains several claimed pre-Clovis artifacts or geofacts. In situ artifacts have been found in this well-stratified site in association with charcoal. Five different samples have been AMS dated to between 11,300 to 12,675 BP (Before Present).^{[citation needed]}
• Monte Verde II, a site in Chile, was occupied from 11,800 to 12,000 years BP.^{[citation needed]}
• Taima Taima, Venezuela has cultural material very similar to Monte Verde II, dating to 12,000 years BP.^{[citation needed]} Recovered artifacts of the El Jobo complex in direct association with the butchered remains of a juvenile mastodon. Radiocarbon dates on associated wood twigs indicate a minimum age of 13,000 years before the present for the mastodon kill, a dating significantly older than that of the Clovis complex in North America.^[61]
• A cut mastodon tusk found at Page-Ladson, Jefferson County, Florida on the Aucilla River has been dated to 12,300 years BP near a few in situ artifacts of similar age.^[62]
• The Schaefer and Hebior mammoth sites in Kenosha County, Wisconsin indicate exploitation of this animal by humans. The Schaefer Mammoth site has over 13 highly purified collagen AMS dates and 17 dates on associated wood, dating it to 12,300-12,500 radiocarbon years before the present. Hebior has two AMS dates in the same range. Both animals show conclusive butchering marks and associated non-diagnostic tools.^[63]
• A site in Walker, Minnesota with stone tools, alleged to be from 13,000 to 15,000 years old based on surrounding geology, was discovered in 2006.^[64]
• In a 2011 article ^[4] in Science, Waters et al. 2011 describe an assemblage of 15,528 lithic artifacts from the Debra L. Friedkin site west of Salado, Texas. These artifacts (including 56 tools, 2,268 macrodebitage and 13,204 microdebitage) define the Buttermilk Creek Complex formation, which stratigraphically underlies a Clovis assemblage. While carbon dating could not be used to directly date the artifacts, 49 samples from the 20 cm Buttermilk floodplain sedimentary clay layer in which the artifacts were embedded were dated using optically stimulated luminescence (OSL). Eighteen OSL ages, ranging from 14,000 to 17,500 ka were obtained from this layer. The authors report "the most conservative estimate" of the age of the Buttermilk clays range from 13,200 to 15,500 ka, based on the minimum age represented by each of the 18 OSL ages.
• Human coprolites have been found in Paisley Caves in Oregon, carbon dated at 14,300 years ago. Genetic analysis revealed that the coprolites contained mtDNA haplogroups A2 and B2, two of the five major Native American mtDNA haplogroups.^[65][66]
• The Mud Lake site, in Kenosha County, Wisconsin consists of the foreleg of a juvenile mammoth recovered in the 1930s. Over 100 stone tool butchering marks are found on the bones. Several purified collagen AMS dates show the animal to be 13,450 rcybp with a range of plus or minus 1,500 rcybp variance.^[67]
• Meadowcroft Rockshelter in southwestern Pennsylvania, excavated 1973-78, with evidence of occupancy dating back from 16,000 to 19,000 years ago.^[68]
• Cactus Hill in southern Virginia, with artifacts such as unfluted bifacial stone tools with dates ranging from c. 15,000 to 17,000 years ago.^[69]
• Sixty-eight stone and bone tools discovered in an orchard in East Wenatchee, Washington in 1987, excavated in 1988 and 1990. Five of the Clovis points are on display at the Wenatchee Valley Museum & Cultural Center.^[70]

See also

• Archaeology of the Americas
• History of Mesoamerica (Paleo-Indian)
• List of archaeological periods (Mesoamerica)
• List of archaeological periods (North America)
• Naco-Mammoth Kill Site

Notes

1. ^ History of the Mark Twain National Forest from the website of the Mark Twain National Forest
2. ^ "''The Concise Oxford Dictionary of Archaeology.''". Enotes.com. http://www.enotes.com/arch-encyclopedia/rcybp. Retrieved 2011-03-27. 
3. ^ ^{a b} Haynes, Gary (2002). The Early Settlement of North America: The Clovis Era. New York: Cambridge University Press. p. 52. ISBN 0521524636. 
4. ^ ^{a b c} Waters, Michael; Forman, Jennings, Nordt, Driese, Feinberg, Keene, Halligan, Lindquist, Pierson, Hallmark, Collins and Wiederhold (2011). "The Buttermilk Creek Complex and the Origins of Clovis at the Debra L. Friedkin Site, Texas". Science 331 (25): 1599–1603. doi:10.1126/science.1201855. PMID 21436451. http://media.kansas.com/smedia/2011/03/24/13/article.source.prod_affiliate.80.pdf. Retrieved 2011-03-24. 
5. ^ "Monte Verde Under Fire". Archaeology.org. 1999-10-18. http://www.archaeology.org/online/features/clovis/. Retrieved 2011-02-06. 
6. ^ "Pedra Furada, Brazil: Paleoindians, Paintings, and Paradoxes: An interview with Drs. Niède Guidon, Anne-Marie Pessis, Fabio Parenti, Claude Guérin, Evelyne Peyre, and Guaciara M. dos Santos". Athenapub.com. http://www.athenapub.com/10pfurad.htm. Retrieved 2011-03-27. 
7. ^ ""Brazilian Findings Spark Archeological Debate" by Alex Bellos". Cabrillo.edu. http://www.cabrillo.edu/~crsmith/pedrafurada.html. Retrieved 2011-03-27. 
8. ^ ""Stones of contention" by David Meltzer". Space.newscientist.com. 1995-06-24. http://space.newscientist.com/article/mg14619834.000-stones-of-contention.html. Retrieved 2011-03-27. 
9. ^ 54. The oldest Americans Archaeological sites by George Weber.
10. ^ Pearson, Georges; Ream, Joshua (2005). "Clovis on the Caribbean Coast of Venezuela". Current Research in the Pleistocene 22: 28–31. ISSN 8755-898X. 
11. ^ "Southeastern Prehistory: Paleoindian Period". National Park Service. http://www.nps.gov/history/seac/outline/02-paleoindian/index.htm. Retrieved 2008-04-28. 
12. ^ Lepper, Bradley T. (1999). "Pleistocene Peoples of Midcontinental North America". In Bonnichsen, Robson; Turnmire, Karen. Ice Age People of North America. Corvallis: Oregon State University Press. pp. 362–394. 
13. ^ Largent, Floyd; Interviewees: Allen West GeoScience Consulting and Albert Goodyear South Carolina Institute of Archaeology and Anthropology. "THE CLOVIS COMET Part I: Evidence for a Cosmic Collision 12,900 Years Ago". The Mammoth Trumpet 23 (1). http://allendale-expedition.net/publications/comet.pdf. Retrieved 2011-02-06. 
14. ^ Firestone, R. B.; et al. (2007). "Evidence for an extraterrestrial impact 12,900 years ago that contributed to the megafaunal extinctions and the Younger Dryas cooling". PNAS 104 (41): 16016–16021. doi:10.1073/pnas.0706977104. PMC 1994902. PMID 17901202. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1994902. 
15. ^ Sandy Harrison. "''Comet impact theory disproved''". Bristol.ac.uk. http://www.bristol.ac.uk/news/2009/6123.html. Retrieved 2011-03-27. 
16. ^ Semeniuk, Ivan (September 2009). "Ice Age Impact". Sky and Telescope: 20–25. 
17. ^ ^{a b c d} Mann, Charles C. (2005). 1491: new revelations of the Americas before Columbus 
18. ^ "America's Stone Age Explorers". Nova. PBS TV. 2004. http://www.pbs.org/wgbh/nova/stoneage/. Retrieved 2006-06-01. 
19. ^ ^{a b} Fagundes, Nelson J.R. et al. (2008) "Mitochondrial Population Genomics Supports a Single Pre-Clovis Origin with a Coastal Route for the Peopling of the Americas" The American Journal of Human Genetics 82(March): pp. 1-10, doi:10.1016/j.ajhg.2007.11.013
20. ^ Waters, Michael; Forman, Steven; Jennings, Thomas; Nordt, Lee; Driese, Steven, Feinberg, Joshua; Keene, Joshua; Halligan, Jessi; Lindquist, Anna; Pierson, James; Hallmark, Charles; Collins, Michael; Wiederhold, James (2011-03-25). "The Buttermilk Creek Complex and the Origins of Clovis at the Debra L. Friedkin Site, Texas". Science 331 (6024): 1599–1603. doi:10.1126/science.1201855. PMID 21436451. http://www.sciencemag.org/content/331/6024/1599.short. Retrieved 2011-03-27. 
21. ^ Wilford, John (2011-03-24). "Arrowheads Found in Texas Dial Back Arrival of Humans in America". The New York Times. http://www.nytimes.com/2011/03/25/science/25archeo.html?pagewanted=all. Retrieved 2011-03-27. 
22. ^ "Ancient hearth tests carbon dating (Pedra Furada) - 17 November 2003". Sci.tech-archive.net. http://sci.tech-archive.net/Archive/sci.archaeology/2009-09/msg00169.html. Retrieved 2011-02-06. 
23. ^ H. Valladas, N. Merciera, M. Michaba et al., TL age-estimates of burnt quartz pebbles from the Toca do Boqueir o da Pedra Furada (Piaui, Northeastern Brazil)
24. ^ A revised chronology of the lowest occupation layer of Pedra Furada Rock Shelter, Piauí, Brazil: the Pleistocene peopling of the Americas G. M. Santos, M. I. Bird, F. Parenti et al.
25. ^ "Scientist: Man in Americas earlier than thought - CNN". Articles.cnn.com. 2004-11-18. http://articles.cnn.com/2004-11-17/tech/carolina.dig_1_oldest-radiocarbon-topper-site-human-sites?_s=PM:TECH. Retrieved 2011-03-27. 
26. ^ "New Evidence Puts Man In North America 50,000 Years Ago". Sciencedaily.com. 2004-11-18. http://www.sciencedaily.com/releases/2004/11/041118104010.htm. Retrieved 2011-03-27. 
27. ^ "Homepage - Rockshelter Artifacts". Heinz History Center. http://www.heinzhistorycenter.org/secondary.aspx?id=150. Retrieved 2011-03-27. 
28. ^ "First Americans arrived 2500 years before we thought - life - 24 March 2011". New Scientist. http://www.newscientist.com/article/dn20287-first-americans-arrived-2500-years-before-we-thought.html. Retrieved 2011-03-27. 
29. ^ Hanna, Bill (2010-08-28). "Texas artifacts 'strongest evidence yet' that humans arrived in North America earlier than thought". Star-telegram.com. http://www.star-telegram.com/2011/03/24/2947233/texas-artifacts-strongest-evidence.html. Retrieved 2011-03-27. 
30. ^ "Athena Review 2,3: Recent Finds in Archaeology: Pre-Clovis occupation on Virginia's Nottoway River". Athenapub.com. http://www.athenapub.com/cacthill.htm. Retrieved 2011-03-27. 
31. ^ Madsen 152
32. ^ Hranicky, Wm Jack (2010). Recording Clovis Points: Techniques, Examples and Methods (Second ed.). Bloomington, Indiana: AuthorHouse. pp. 31, 33, 37. ISBN 978-1-4520-1224-7. http://books.google.com/books?id=0ncSo-dDBk4C&pg=PA37&lpg=PA37&dq=page+ladson+clovis&source=bl&ots=I3rPgCDE48&sig=bfhpGNrPwDI-PDcK2ugfyXiWPFM&hl=en&ei=Yqa_Tre6NYe3tgeHu5m1CA&sa=X&oi=book_result&ct=result&resnum=4&sqi=2&ved=0CC8Q6AEwAw#v=onepage&q=page%20ladson%20clovis&f=false. 
33. ^ "Taima Taima". Bradshawfoundation.com. http://www.bradshawfoundation.com/journey/taima-taima-text.html. Retrieved 2011-03-27. 
34. ^ ^{a b c} Madsen 157
35. ^ "Cavernas do Peruaçu Federal Environmental Protection Area (APA) / Veredas Do Peruaçu State Park - UNESCO World Heritage Centre". Whc.unesco.org. 1998-09-16. http://whc.unesco.org/en/tentativelists/1124/. Retrieved 2011-03-27. 
36. ^ Tanana River Valley Archaeology circa 14,000 to 9000 B.P.. Charles E. Holmes. Arctic Anthropology. Vol. 38, No. 2, Between Two Worlds: Late Pleistocene Cultural and Technological Diversity in Eastern Beringia (2001), pp. 154-170
37. ^ "Researchers, Led by Archaeologist, Find Pre-Clovis Human DNA". Newswise.com. 2008-02-04. http://newswise.com/articles/view/539341/. Retrieved 2011-03-27. 
38. ^ "Early hunter-gatherers in the Americas: perspectives from central Brazil - page 3 | Antiquity". Findarticles.com. 1998. http://findarticles.com/p/articles/mi_hb3284/is_n277_v72/ai_n28711513/pg_3/. Retrieved 2011-03-27. 
39. ^ "Northern Great Basin Prehistory Project, Archaeological and Geoarchaeological Field School, University of Oregon, Summer Sessions". Pages.uoregon.edu. http://pages.uoregon.edu/ftrock/connley_caves_description.php. Retrieved 2011-03-27. 
40. ^ Late Pleistocene Settlement in the Nenana Valley, Central Alaska William R. Powers and John F. Hoffecker. American Antiquity Vol. 54, No. 2 (Apr., 1989), pp. 263-287
41. ^ "53. Relatives in South America". Andaman.org. http://www.andaman.org/BOOK/chapter54/text-Taguatagua/text-Taguatagua.htm. Retrieved 2011-03-27. 
42. ^ Peter N. Jones, [e-mail] Bauu Institute, [e-mail] (2007-10-19). "Multiple Colonizations and Many Routes in the Peopling of the Americas". Bauuinstitute.com. http://www.bauuinstitute.com/Articles/PleistoceneAmericanColonization.html. Retrieved 2011-03-27. 
43. ^ A&M University Press Article
44. ^ Guidon, Niède. 1986 "Las Unidades Culturales de Sao Raimundo Nonato - Sudeste del Estado de Piaui-Brasil"; New Evidence for the Pleistocene Peopling of the Americas: 157-171. Edited by Alan Bryan. Center for the Study of Early Man. University of Maine. Orono.
45. ^ New Evidence Puts Man In North America 50,000 Years Ago from the ScienceDaily website
46. ^ Scientist: Man in Americas earlier than thought, a CNN article on the South Carolina discoveries
47. ^ Madsen 153
48. ^ Science, May 9, 2008, Ancient Algae Suggest Sea Route for First Americans
49. ^ José Luis Lorenzo and Lorena Mirambell (coordinadores). "Tlapacoya: 35,000 años de historia del Lago de Chalco" Colección Científica núm 155, serie prehistória, Instituto Nacional de Antropología, México, 1986
50. ^ Joaquín García-Bárcena. "Primeros pobladores: La Etapa Lítica en México." Arqueología Mexicana, Vol. IX, núm. 52, pp. 28–29, 2001.
51. ^ Jacobs et al. 2004. GENES, DIVERSITY, AND GEOLOGIC PROCESS ON THE PACIFIC COAST. Annual Review of Earth and Planetary Sciences 32: 601-652
52. ^ Bradley, Bruce; 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. http://planet.uwc.ac.za/nisl/Conservation%20Biology/Karen%20PDF/Clovis/Bradley%20&%20Stanford%202004.pdf. 
53. ^ Westley, Kieran; Justin Dix "The Solutrean Atlantic Hypothesis: A View from the Ocean" Journal of the North Atlantic 2008 1:85–98 [1]
54. ^ Straus, Lawrence G. (April 2000). "Solutrean Settlement of North America? A Review of Reality". American Antiquity (Society for American Archaeology) 65 (2): 219–226. doi:10.2307/2694056. ISSN 00027316. JSTOR 2694056. 
55. ^ Bradley, Bruce; Stanford, Dennis "The Solutrean-Clovis connection : reply to Straus, Meltzer and Goebel" World archaeology 38:44, 704-714, Taylor & Francis, 2006
56. ^ Fagundes, Nelson J.R.; et al. (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. http://www.familytreedna.com/pdf/Fagundes-et-al.pdf. Retrieved 2008-07-04. 
57. ^ A revised chronology of the lowest occupation layer of Pedra Furada Rock Shelter, Piauí, Brazil: the Pleistocene peopling of the Americas G. M. Santos, M. I. Birdb, F. Parenti et al.
58. ^ Walter A. Neves and Mark Hubbe: Cranial morphology of early Americans from Lagoa Santa, Brazil: Implications for the settlement of the New World. Laboratorio de Estudos Evolutivos Humanos, Departamento de Genetica e Biologia Evolutiva, Instituto de Biociencias, Universidade de São Paulo.
59. ^ C. Michael Hogan, Cueva del Milodon, Megalithic Portal, 13 April 2008
60. ^ Calvin J. Heusser (2003) Ice Age Southern Andes: A Chronicle of Paleoecological Events, Elsevier, 240 pages ISBN 0444514783
61. ^ An El Jobo Mastodon Kill at Taima-taima, Venezuela Science 16 June 1978. Vol. 200 no. 4347 pp. 1275-1277 DOI: 10.1126/science.200.4347.1275. ALAN L. BRYAN, RODOLFO M. CASAMIQUELA, JosÉ M. CRUXENT, RUTH GRUHN and CLAUDIO OCHSENIUS
62. ^ Webb et al. 2006 First Floridians and Last Mastodons, Springer
63. ^ Schafer from the website of the "Friends of the Ice Age" in Kenosha County, Wisconsin
64. ^ Ancient Stone "Tools" Found; May Be Among Americas' Oldest from the National Geographic website
65. ^ Michael Balter. "DNA from Fossil Feces breaks Clovis Barrier". Sciencemag.org. http://www.sciencemag.org/cgi/content/summary/320/5872/37. Retrieved 2011-03-27. 
66. ^ New Scientist 12/4/08 pg 15
67. ^ Mud Lake Site from the website of the "Friends of the Ice Age" in Kenosha County, Wisconsin
68. ^ "The Greatest Journey", James Shreeve, National Geographic, March 2006, pg. 64
69. ^ Pre-Clovis Occupation on the Nottoway River in Virginia Pre-Clovis Occupation on the Nottoway River in Virginia from the website of the Athena Review, Vol.2, no.3
70. ^ Lee, Mike (December 27, 1999). "Work on 1987 discovery on hold". Tri-City Herald (Kennewick, Washington: The McClatchy Company). OCLC 17157840. http://www.tri-cityherald.com/1999/12/27/136330/work-on-1987-discovery-on-hold.html. Retrieved {{subst:today}}. 

References

• Madsen, David B., ed. Entering America: Northeast Asia and Beringia Before the Last Glacial Maximum. Salt Lake City: University of Utah Press, 2004. ISBN 978-0-87480-786-8.

Further reading

• Dixon, E. James (1999). Bones, Boats and Bison: Archeology and the First Colonization of Western North America. Albuquerque: University of New Mexico Press. ISBN 0-826-32057-0. OCLC 42022335. 
• Schurr, Theodore G. (2000). "Mitochondrial DNA and the Peopling of the New World". American Scientist 88 (3): 246–253. doi:10.1511/2000.3.246. ISSN 0003-0996. 
• Stanford, Dennis; and Bruce Bradley (2002). "Ocean Trails and Prairie Paths? Thoughts About Clovis Origins.". In Nina G. Jablonski (ed.). The First Americans: The Pleistocene Colonization of the New World (Memoirs of the California Academy of Sciences, No. 27.). edited proceedings of The Fourth Wattis Symposium, 'The First Americans: The Pleistocene Colonization of the New World,' October 2, 1999. San Francisco: California Academy of Sciences. pp. 255–271. ISBN 0-940-22849-1. 
• Straus, Lawrence G. (April 2000). "Solutrean Settlement of North America? A Review of Reality". American Antiquity (Society for American Archaeology) 65 (2): 219–226. doi:10.2307/2694056. ISSN 00027316. JSTOR 2694056. 
• Kennett, D. J.; Kennett, J. P.; West, A.; Mercer, C.; Que Hee, S. S.; Bement, L.; Bunch, T. E.; Sellers, M. et al. (2009). "Nanodiamonds in the Younger Dryas Boundary Sediment Layer". Science 323 (5910): 94. doi:10.1126/science.1162819. PMID 19119227. 

External links

• Blackwater Draw Site Weblog Current research at the Clovis type site
• Stone Age Columbus BBC TV programme summary
• Texas Beyond History
• Carbon-rich layer fortifies theory on comet impact