The current debate about the origins of the Paleoindians of America.

Schiffner, Daniel C.

In recent years, contributions from the fields of archeology, physical anthropology, linguistics, and genetics have revolutionized the study of the origins, timing and process of human settlement in America. This re-thinking of the origins question has been based on a multi-disciplinary approach to the subject. Not only have traditional beliefs been questioned, but a far more sophisticated body of new materials has emerged to analyze the basic issues involved in determining the origins of human settlement in the Americas. From dental remains, the physical anthropologists have been able to obtain specimens that are both highly resistant to post-mortem alterations and directly related to population-specific evolutionary changes. At the same time, the study of gene frequencies and changing distributions of genetic markers among Native American populations has produced new data on historical settlement and migration patterns, which often challenge the archaeological evidence of early human migrations. In turn, this new research, much of which has occurred only in the last twenty years, has itself led to new debates and the emergence of new questions. The aim of this essay is to provide the reader with a brief guide to this literature and the questions that have been raised.

The idea that the Western Hemisphere was first peopled by a migration of Asians who reached the New World via a land bridge across the Bering Straits was proposed as early as the 16th century by the Jesuit chronicler Padre Jose de Acosta. This notion did not become the dominant hypothesis, however, until the early 20th century. (1) Until well into the 19th century there was constant speculation about various migrations of Old World peoples who were supposed to have built the temples and mounds found all over the Americas. In the early decades of the 20th century, American archeologists finally began to adopt the 19th-century European model of stratigraphic superposition, or the process of dating based on specimen location in geological strata. This was the first coherent dating method available to researchers, and among the first such studies were those by Manuel Gamio in the Valley of Mexico in 1911. By the 1930s, both stratigraphic and seriation analysis, or the dating based on culture and era-specific pottery styles, had become the norm throughout the Americas, and the results quickly showed the coherent evolution of American societies. (2) Carbon-14 analysis was also added after 1949 to date artifacts emerging from the systematic exploration of numerous sites from Alaska to Patagonia.

Although some 19th century findings had suggested the existence of Neanderthal man in the Western Hemisphere, this evidence was rejected by the 1910s, and since then it is generally accepted that only full Homo sapiens sapiens (or anatomically modern man) migrated to the New World. (3) By the 1920s, the discovery of unique stone "Clovis point" projectiles in Clovis, New Mexico and the appearance of these as well as Folsom projectiles in kill sites near large mammal bones from northern Alaska to Guatemala, suggested an original big game hunting culture that was deemed typical of all early man. This Clovis culture was assumed to have lasted from about 12,000 BP (years before present) to about 10,000 BP. A consensus emerged by the 1930s, which lasted to the 1980s, that Asian migrants came in small hunting and gathering bands and were primarily big game hunters. It was even suggested that these humans wiped out the giant mammals in the Americas, though the extinction of even those animals that were not eaten by man suggests a far more complex cause for the disappearance of late Pleistocene mammals. (4)

Based on geological evidence and the discovery of human remains, many assumed that Homo sapiens sapiens arrived in America from Asia about 12,000 BP when the Bering land bridge was open in one of its periodical dry land phases. This assumption was rooted in the idea that glaciers blocked these early hunters' land route to the south from Alaska until the last ice age ended, at about this time. Once the glaciers receded, the founding immigrants were able to people the rest of the Americas in a few hundred years, probably arriving in Patagonia around 11,000 BP. (5)

However, by the mid 1980s these models were being challenged, even by the archeologists studying stone tools. Non-Clovis point projectiles were discovered in South America, and sites were being explored which were not associated with large mammals. The carbon-14 dating of some sites began to push back the origins of human settlement earlier than 12,000 BP. For example, the well-studied excavations at Monte Verde in Chile were dated at 13,000 BP. (6) Finally, most archeologists concluded that a much earlier date of arrival must have occurred, even if no human remains existed from this earlier period. As Irving concluded for this new school of archeological research, "the great diversity of projectile point manufacturing techniques present 10,000-12,000 years ago precluded any possibility of a first migration from Asia ..." coming anywhere less than 2 or 3 millennia before. Moreover," ... the variety of ecological adaptations already evident by 12,000 B.P., ranging from interior subarctic to coast-tropical" ... also suggests the same conclusion. (7)

In an effort to explain the increasingly older dates from newer South American excavations, defenders of the Clovis model suggested an extraordinarily rapid advance of the hunting and gathering bands through the Americas and often challenged the validity of the new finds. (8) Yet, further studies supported the older dating of these new finds, especially those of Monte Verde. Thus, even traditional archeologists began to question the validity of the Clovis dating. In a major critique of the use of carbon-14 dates for this period, Stuart Fiedel suggested that the terminal Pleistocene dates for these sites, for climatic reasons, were 2,000 years too young. Using tree-ring time data, sediment core analyses from bodies of water, and ice layer dating from Greenland, he suggested that "comparisons of [these] ice core dates, radiocarbon dates, and uranium-thorium dates indicate that there were several periods in the late Pleistocene and early Holocenc when abnormally large ratios of [carbon-14] effectively counterbalanced the radioactive decay rate, such that radiocarbon ages appear to remain constant over centuries ... " (9) It is therefore necessary to use these other dating schemes to counteract what he calls the "plateau effect" in the carbon- 14 dates and this "may push initial Clovis occupation of the Southwest back to about 13,350-13,500 BP ..." to Thus, slowly but inevitably the dates of the initial migrations were pushed farther away from those predicted by the Clovis model.

Despite such arguments, the Clovis culture model remained powerful and was soon tied to a three-migration hypothesis proposed by a historical linguist and two physical anthropologists. In a major 1986 essay, Joseph Greenberg, Chrystie Turner and Stephen Zegura argued that three founding migrations peopled the Americas and that each migration formed one of the putative three language families still found in native New World populations. (11) Greenberg, based on his own unpublished research, claimed that Native American languages could be grouped into three families: Na-Dene (Athapaskan, Tlingit and Haida-NW coast); Aleut-Eskimo; and a general "Amerind" family for all of the remaining Native American groups. (12) This three family model, according to Turner, was supported as well by dental evidence of prehistoric human remains suggesting three separate migrations. Finally, Zeguta tentatively suggested that the genetic data supported this hypothetical three-migration model as well.

In the last two decades, geneticists and physical anthropologists have intensified the debate over the peopling of the Americas and challenged the original three-migration model. These investigators have used genetic material taken both from archaeological samples of human remains, (13) and from extant populations of Native Americans. To date, a majority of the studies have used mitochondrial DNA (mtDNA), an abundant, rapidly evolving source of genetic material. Comparisons of mtDNA from different populations can reveal their molecular relatedness and the approximate time since molecular divergence. These times can, in theory, correlate with actual population characteristics and histories. Because mitochondria are maternally inherited, mtDNA data can only be applied to female migrations and evolution. Because of the prevalence of both patrilocal and matrilocal societies in the Americas, the genders had varying degrees of mobility, depending on the specific customs of the tribe or society. These differences in mobility could have had significant effects on the gene flow within and between populations. For this reason, recent studies have attempted to utilize the paternally inherited Y chromosome as well as biparentally inherited autosomal genetic markers to study the relatedness and histories of populations. (14)

The mtDNA analyses have revealed that almost all Native Americans belong to four main lineages--A, B, C, or D. (15) These lineages, or haplogroups, are defined by specific restriction fragment length polymorphisms and base pair deletions. The four Native American haplogroups show close similarity with Asian mtDNA, (16) and trace back to a now-extinct model haplogroup common to both Asians and Americans. (17) This limited genetic diversity is widely interpreted as the result of a bottleneck effect in which the founding Asian groups that crossed the Bering land bridge possessed limited genetic diversity.

Based on studies of Native American mtDNA, scientists have arrived at many different and often-contradictory conclusions about the number and chronology of the migrations from Asia to the Americas. Early studies by leading geneticists in the mid 1990s, such as L.L. Cavalli-Sforza and his co-authors' in their book The History and Geography of Human Genes and D.C. Walker's major summation of mitochondrial DNA research, supported Greenberg's three-migration model. (18) Other early studies, which included work by Ward, Torroni, and their colleagues, suggested that the Americas were peopled by two separate Amerindian migrations followed by a Na-Dene migration. (19) They proposed a first migration from Central Asia through Siberia and across the Bering land bridge occurring at between 26,000-34,000 BP. This initial wave of immigrants consisted only of individuals possessing haplogroups A, C, and D. The second migration originated in Asia and bypassed Siberia before crossing Beringia (as the land bridge Between Asia and Alaska is called in the literature). This group possessed only haplogroup B and arrived in the Americas between 12,000 and 15,000 year BP. Within the framework of this model, Torroni in his several earlier articles proposed that the Na-Dene arrived in a single migration that occurred 7,200-9,000 BP. Although the three-migration model would be challenged by later findings, these first major studies also argued, along with the new schools of archeology, that the age of the migration had to be pushed farther back than previously suggested in the Clovis paradigm. According to these genetic findings, the Native American groups separated from their Northeastern Asian ancestors about 25,000-35,000 BP and migrated at anytime between 15,000-35,000 BP. (20)

Despite its initial support for the three-migration model, emerging genetic data produced several other persuasive theories on the arrival of man in America to supplant this early notion. Horai and his associates in 1993 proposed that each of the four main haplogroups was introduced to the Americas by a separate wave of migration across Beringia. Because of the wide distribution of all four lineages throughout the Americas, however, this four-migration theory has been widely, discarded in recent studies. (21) Equally, the Greenberg three-migration hypothesis was rejected by the mid 1990s, (22) as later studies using different mtDNA markers and more advanced molecular assays have generally not confirmed the three migration dates and conclusions.

Recently, many researchers have concluded that the results of mtDNA sequencing and diversity data indicate that the New World was initially populated by a single migration event with subsequent radiation throughout the Americas. (23) By calculating the expansion times of haplogroup A within the Na-Dene and Amerindian groups, the Bonatto-Salzano and Stone-Stoneking research teams argue that the ancestors of these two groups arrived in the New World in the same migration. (24) Based on their haplogroup A analyses, these researchers estimated the time of this single migration at 22,000-55,000 BP and 23,000-37,000 BP, respectively. In addition, Silva and his colleagues agree that a single wave of migration resulted in the peopling of the Americas. These data support a somewhat later arrival at 18,600-23,000 BP. (25) Following these single migration models, it is likely that during these time spans, a continuous flow of small groups crossed Beringia and populated the Americas in search of food and other resources. Accordingly, the distinct linguistic and cultural groups emerged after the expansion and radiation of the founding population throughout North, Central, and South America. (26)

Scientists have also begun to study patterns in the non-recombining region of the paternally inherited Y chromosome as an alternative source of evidence to complement the maternal mtDNA findings. Three major Y chromosomal groupings have been found in Native American populations: the M3, (27) the RPS4Y-T, (28) and the DYS199-T (29) lineages. As with the mtDNA analyses, the emerging Y chromosomal data has lead to several different interpretations of the number and timing of migrations to the New World. Early studies in this area indicate that a single migration from Asia was responsible for the peopling of the Americas and that cultural and linguistic divisions developed after this early colonization. Support for this model is derived largely from studies of the DYS199-T allele. This Y chromosomal marker is found exclusively in the Siberian Eskimos, Coastal Chukchi, and Native Americans. Based on the genetic distribution of this allele, researchers speculate that the Americas were peopled by a single migration from Asia that occurred as long as 30,000 BP with subsequent radiation and linguistic differentiation. (30)

In this rapidly developing area, differing points of view have already developed to estimate the origin, timing, and number of migrations to the New World. Lell and his co-authors have recently refuted this single migration interpretation of Y chromosome data. This group asserts that humans arrived in the Americas in two migrations from distinct regions of Siberia. According to this argument, the first wave of migration consisted of immigrants from the Chukotka region of southern Middle Siberia who crossed the Bering land bridge approximately 20,000-30,000 BP. These founders possessed the M3 and M45a Y chromosome lineages and populated North, Central, and South America. The second migration occurred approximately 7,000-9,500 BP and consisted of immigrants from Kamchatka and the Lower Amur River basin in eastern Siberia. This group of immigrants possessed the RPS4Y-T and M45b Y chromosome lineages and expanded in North and Central America to form the Na-Dene and northern Amerindian groups. (31) This model has raised many questions about the entry of man into the New World and has intensified the debate over the interpretation of Y chromosome data. (32) Future studies that look at more Y chromosomal and autosomal loci, include more samples from the Na-Dene and Eskimo-Aleut populations, and correlate their results with existing mtDNA findings will help resolve these issues. In addition, the recent work by American geneticists to elucidate the genetic origins of many isolated Native American peoples may further help answer these questions. (33)

Despite these ongoing debates, consensus has slowly emerged on at least one central point. Whatever the internal variations, almost all genetic studies put the separation point between Asian populations and American Indian peoples at roughly 25,000 BP, with a margin of error of a few thousands of years. This consensus among geneticists has severely challenged the archeologists and led to a general abandonment of the 12,000 BP initial date. Moreover, it has required a rethinking of the pattern of settlement in the Americas, especially as the South American sites of early settlement are contemporaneous with or earlier than the Clovis sites of North America.

Initially, most researchers assumed that humans moved south only after the opening of the continental ice barriers at approximately 12,000 BP. According to this early view, the rapid settlement of the Americas could have been achieved only by a "blitzkrieg" type of expansion that occurred with natural population growth rates of over 3.5% per annum. Such rates are extraordinary even by today's standard. This model was heavily dependent on the old Clovis paradigm and the outdated estimates of dating. Recently, simulation models have suggested that the best fit for the human migration south was a pre- 12,000 BP coastal-boat "leapfrogging" migration that bypassed the glacial barriers. Convincing evidence suggests that humans were using watercraft by 40,000 BP (as the colonization of Australia proved). This migration would have been based on the exploitation of the rich food environment provided by marine mammals, fishing, and the gathering of shellfish. In addition, these migrants would have had a level of growth of less than .01% per annum. This figure would have enabled these clusters of human populations to maintain their genetic diversity at a level that has been found among extant and extinct Native American populations. (34)

Thus, the Clovis-Blitzkrieg paradigm no longer seems to hold, nor is the Greenberg three languages with three founding migrations model accepted. Although there is still no agreement on the number of founding waves of migration, the exact age of the founding migrations, or the coherence and combination of Native American groupings, enough of a consensus has been reached to suggest unqualified support for an Asian origin to early Americans and an early migration to America of approximately 20,000-30,000 BP. To add to the criticisms of the original models waged by geneticists and physical anthropologists, linguists also have widely rejected the three language families postulated by Greenberg. These linguists have especially attacked his all-encompassing Amerindian language family as being conceptually flawed and unproven. They have also argued that, given the current state of knowledge, linguistic reconstruction cannot be used to establish the dates or number of migrations to the Americas. (35)

Equally, much of the physical evidence of human teeth and bones has also been shown to be far less clear than originally proposed, (36) although a new school of physical anthropologists has begun to question the conclusions of the geneticists and archeologists in this area. Some physical anthropologists are now arguing that cranial and tooth remains from earlier humans in the Americas, especially those found recently in South America, suggest the possibility of a non-Siberian migration. (37) They find that the bones of the earliest colonizers of the Americas were morphologically distinct from northeast Asians and recent American Indians. Despite the conclusions of this new school of thought, the current consensus still holds among the majority of scholarly groups that humans arrived from Asia across Beringia as Homo sapiens sapiens and that this occurred at least 15,000 years earlier than previously suggested. Moreover, these early migrants incorporated a much wider range of food gathering techniques than traditionally suggested in the Clovis model. Finally, the coastal enclaves are now seen to be the major source for the leapfrogging of populations past the glacier land barriers in the settlement of the Americas. Based on the diversity and sheer number of the above-presented arguments, the debate surrounding the arrival of man in America is clearly a contentious and rapidly evolving field that merits the attention of the historical, anthropological, archaeological, and scientific communities.

ENDNOTES

(1.) Stuart J. Fiedel, Prehistory of the Americas (2d ed; Cambridge, 1992), p.

(2.) Fiedel, Prehistory of the Americas, pp. 7-9.

(3.) William N. Irving, "Context and Chronology of Early Man in the Americas," American Review of Anthropology 14 (1985): 530. The work of W.H. Holmes in 1897 and A Hrdlicka in 1907 effectively rejected all supposed Neanderthal findings for the New World--and this position was never again proposed.

(4.) Thomas D. Dillehay, The Settlement of the Americas: A New Prehistory (New York, 2000), chapter 2.

(5.) A good summation of this traditional view is found in Irving "Context and Chronology," p. 530-534.

(6.) Dillehay, The Settlement of the Americas, chapter 5. as well as Thomas D. Dillehay, Monte Verde, a late Pleistocene settlement in Chile (2 vols.; Washington, D.C, 1989-1997). For the latest defense of the radio carbon dates of at least 12,500 BP see , R.E. Taylorm et. al., "Radiocarbon Analyses of Modern Organics at Monte Verde, Chile: No Evidence for a Local Reservoir Effect," American Antiquity 64:3 (1999): 455-460.

(7.) Irving "Context and Chronology," p. 537.

(8.) See for example David G. Anderson and J. Christoper Gillam, "Paleoindian Colonization of the Americas: Implications from an Examination of the Physiography, Demography and, Artifact Distribution," American Antiquity 65:1 (2000): 43-66; and Todd A. Surovell, Early Paleoindian Women, Children, Mobility, Fertility, American Antiquity 65:3 (2000): 493-508.

(9.) Stuart J. Fiedel, "Older Than We Thought: Implications of Corrected Dates for Paleoindians," American Antiquity 64:1 (1999): 99.

(10.) Fiedel, "Older than We Thought," p. 102.

(11.) Joseph H. Greenberg, Christy G. Turner II and Stephen L. Zegura, "The Settlement of the Americas: A Comparison of the Linguistic, Dental and Genetic Evidence," Current Antrhopology 27:5 (December 1986): 477.

(12.) Greenberg, et. al. "The Settlement of the Americas," p. 478.

(13.) See for example, Dario A. Demarchi, et. al., "Absence of the 9-bp Deletion of Mitochondrial DNA in Pre-Hispanic Inhabitants of Argentina," Human Biology 73:4 (August 2001): 575-582 which was based on 34 skeletal remains from five archeological sites in Argentina.

(14.) Natalia R. Mesa et al., "Autosomal, mtDNA, and Y-Chromosome Diversity in Amerinds: Pre- and Post-Columbian Patterns of Gene Flow in South America" American Journal of Human Genetics 67 (2000): 1277-1286.; and L. B. Jorde, et. al., The Distribution of Human Genetic Diversity: A Comparison of Mitochondrial, Autosomal, and Y-Chromosome Data" American Journal of Human Genetics, 66 (2000): 979-988.

(15.) T.G. Schurr, et. al., "Amerindian mitochondrial DNAs have rare Asian mutations," 613-622; S Horai, et.; al., "Peopling of the Americas founder by four major lineages of mitochondrial DNA, Molecular Biology and Evolution 10 (1993): 23-47; Antonio Torroni and D.C. Wallace "mtDNA haplogroups in Native Americans," American Journal of Human Genetics 56 (1995):1234-1236.

(16.) G Bailliet, et. al., "Founder mitochondrial haplotypes in Amerindian populations," American Journal of Human Genetics 55 (1994): 27-33; and M. D. Brown, et. al, "mtDNA haplogroup X: an ancient link between Europe/Western Asia and North America?" American Journal of Human Genetics 63 (1998): 1852-1861.

(17.) A. Tortoni, et. al., "Asian affinities and continental radiation of the four founding Native American mtDNAs," American Journal of Human Genetics 53 (1993) 563-590.

(18.) L. Luca Cavalli-Sforza, Paolo Menozzi and Alberto Piazza, The History and Geography of Human Genes (Princeton, 1994), chapter 6; and D.C. Wallace Mitochondrial DNA Variation in Human Evolution, Degenerative Disease, and Aging," American Journal of Human Genetics 57 (1995): 201-223.

(19.) Also see R. H. Ward, et. al., "Genetic and linguistic differentiation in the Americas," Proceedings of the National Academy of Science USA 90 (1993): 10663-10667; A Torroni, et. al., "Asian affinities and continental radiation of the four founding Native American mtDNAs," American Journal of Human Genetics 53 (1993): 563-590; and A. Torroni, et. al., "Native American mitochondrial DNA analysis indicates that the Amerindian and the Nadene populations were founded by two independent migrations," Genetics 130 (1992): 153-162; Using mtDNA studies, Shields and his colleagues added a novel concept to this model. This team of investigators grouped the mtDNA lineages of the Na-Dene, Eskimo-Aleuts, and the Chukchi of Siberia into the Circumarctic people and concluded that the Na-Dene and Eskimo-Aleuts crossed the Bering land bridge together during a rapid radiation of these Circumarctic people that occurred thousands of years after the Amerindian migration G.F. "Shields, et. al., "mtDNA sequences suggest a recent evolutionary divergence for Beringian and northern North American populations," American Journal of Human Genetics 53 (1993): 549-562. Also see T. G. Schurr, et. al., "Amerindian mitochondrial DNAs have rare Asian mutations at high frequencies, suggesting they derived from four primary maternal lineages," American Journal of Human Genetics 46 (1990): 613-622; and A Torroni, et. al., "Asian affinities and continental radiation;," A Tortoni, et. al., "Native American mitochondrial DNA analysis," and Antonio Torroni, et. al., "Mitochondrial DNA 'clock' for the Amerinds [Chibcha] and its implications for timing their entry into North America," Proceedings of the National Academy of Science 91 (1994): 1158-1162; R. H. Ward, et. al., "Extensive mitochondrial diversity within a single Amerindian tribe, Proceedings of the National Academy of Science USA 88 (1991): 8720-8724.

(20.) Cavalli-Sforza, History & Geography, p. 307.

(21.) Anne C. Stone and Mark Stoneking, " mtDNA analysis of a prehistoric Oneota population. Implication for the peopling of the New World, American Journal of Human Genetics 62 (1998): 1153-1170.

(22.) David J. Meltzer, "Clocking the First Americans" Annual Review of Anthropology 24 (1995): 21-45.

(23.) D. A. Merriwether, et. al., "Distribution of the four founding lineage haplotypes in Native Americans suggests a single wave of migration for the New World," American Journal of Physical Anthropolgy 98 (1995): 411-430; P. Forster, et. al., "Origin and evolution of Native American mtDNA variation: reappraisal," American Journal of Human Genetics 59 (1996): 935-945; and Sandro L. Bonatto and Francisco M. Salzano, "A single and early migration for the peopling of the Americas supported bymitochondrial DNA sequence data, Proceedings of the National Academy of Science USA 94 (1997): 1866-1871.

(24.) Bonatto and Salzano, "A Single and Early Migration," loc.cit. and Stone and Stoneking "mtDNA analysis of a prehistoric Oneota Population," loc. cit.

(25.) Wilson A. Silva, et. al., "Mitochondrial Genome Diversity of Native Americans Supports a Single Early Entry of Founder Populations into America" American Journal of Human Genetics 71 (2002): 187-192.

(26.) Stone and Stoneking "mtDNA analysis of a prehistoric Oneota Population," loc. cit.

(27.) Peter. A. Underhill, et. al., "A pre-Columbian Y chromosome-specific transition and its implications for human evolutionary history," Proceedings of the National Academy of Science USA 93 (1996): 196-200.

(28.) A W. Bergen, et. al., "An Asian-Native American paternal lineage identified by RPS4Y resequencing and microsatellite haplotyping," Annual Review of Human Genetics 63 (1999): 63-80.

(29.) A Ruiz-Linares, et. al. "Microsatellites provide evidence for Y chromosome diversity among the founders of the New World," Proceedings of the National Academy of Science USA 96 (1999): 6312-6317.

(30.) Underhill et. al. "A pre-columbian Y chromosome-specific transition and its implications for human evolutionary history." Proceedings of the National Academy of Sciences 93 (1996): 196-2000. J.T. Lell et. al. Y chromosome polymorphisms and the origins of Native Americans" American Journal of Human Genetics 59 (1996) (Supplement): A 182. T.M. Karafet et. al. "Y Chromosome Markers and Trans-Bering Strait Dispersals," American Journal of Physical Anthropology 102 (1997): 301-314.

(31.) J. T. Lell, et. al., "The Dual Origin and Siberian Affinities of Native American Y Chromosomes" American Journal of Human Genetics 70 (2002): 192-206; and T. M. Karafet, et. al., "Ancestral Asian source(s) of new world Y-chromosome founder haplotypes," American Journal of Human Genetics 64 (1999): 817-831.

(32.) The debate has been led by two Brazilian scholars, Sandro L. Bonatto and Francisco M. Salzano, "A Single and early Migration for the Peopling of the Americas supported by mitochondrial DNA Sequence data," Proceedings of the National Academy of Science 94 (1997): 1866-1871; also see Wilson A. Silva, Jr, et. al., "Mitochondrial Genome Diversity of Native Americans Supports a Single Entry of Founder Populations into America," American Journal of Human Genetics 71 (2002): 187-192; and Anne C. Stone and Mark Stoneking, "mtDNA Analysis of a Prehistoric Oneota Population," loc. cit. Using evidence from the distribution of the Y Chromosomes, Jeffrey T. Lell and his associates have argued for two major migrations for early man, see Jeffrey T. Lell, et.al, "The Dual Origin and Siberian Affinities of Native American Y Chromosomes," American Journal of Human Genetics 70 (2002): 192-206. This position was attacked by Eduardo Tarazona-Santos and Fabrfcio R,. Santos, "The Peopling of the Americas: A Second Major Migration," American Journal of Human Genetics 70 (2002): 1377-1380; and defended by Lylle in the same issue "Reply to Tarazona-Santos and Santos," ibid, pp. 1380-81. Finally Mahli and his associates have most recently challenged the whole idea of defining the number of founding groups, especially as they argue that few North American native populations have been fully evaluated for their mtDNA markers. Ripan S. Mahli, et. al., "The Structure of Diversity within New World Mitochrondrial DNA Haplogroups: Implications for the Prehistory of North America," American Journal of Human Genetics 70 (2002): 906.

(33.) Aside from the works cited above, see see Sandro L. Bonatto and Francisco M. Salzano, "Diversity and Age of the Four Major mtDNA Haplogroups, and their Implications for the Peopling of the New World," American Journal of Human Genetics 61 (1997): 1413-1423; A.S. Goicocoechea, et. al., "Genetic Relationship Between Amerindian Populations of Argentina," American Journal of Physical Anthropology 115 (2001): 1333-1343; Juliana Alves-Silva, et. al., "The Acenstry of Brazilian mtDNA lineages, American Journal of Human Genetics 67 (2000): 444-461; Angelica Gonzalez-Olivier, et. al., "Founding Amerindian Mitochondrial DNA lineages in Ancient Maya from Xcaret, Quintana Roo," American Journal of Physical Anthropology 116 (2001): 230-235; Federika A. Kaestle and David Glenn-Smith, "Ancient Mitochondrial DNA Evidence for Prehistoric Population Movement: The Numic [Western Nevada] Expansion," American Journal of Physical Anthropology 115 (2001): 1-12; C.J Kolman, and E. Bermingham, "Mitochondrial and nuclear DNA diversity in the Chaco and Chibcha Amerinds of Panama," Genetics 147 (1997): 1289-1302; Natalia R. Mesa, et. al., "Autosomal, mtNDA, and Y-Chromosome Diversity in Amerinds: Pre and Post-Columbian Patterns of Gene Flow in South America," American Journal of Human Genetics 67 (2000): 1277-1286; Mauricio L. Moraga, "Mitochondrial DNA Polymorphisms in Chilean Aboriginal Populations: Implications for Peopling of the Southern Cone of the Continent," American Journal of Physical Anthropology 113 (2000): 19-29; Pedro Moral, et. al., "Genetic Variability in the Guahibo Population from Venezuela," American Journal of Human Biology 14 (2002): 21-28; and C.J Kolman, N Sambuughin and E. Bermingham, "Mitochondrial DNA analysis of Mongolian popullations and implication for the origin of New World Founders," Genetics 142 (1996): 1321-1334; and Hiroki Oota, et. al, "Extreme mtDNA Homogeneity in Continental Asian Population," American Journal of Physical Anthropology 118 (2002): 146-153. The Y chromosomes have been studied by Fabricio R. Santos, et. al., "The Central Siberian Origin for Native American Y Chromosomes," American Journal of Human Genetics 64 (1999): 619-628; Eduardo Tarazona-Santos, et. al., "Genetic Differentiation in South Amerindians is Relates to Environmental and Cultural Diversity: Evidence from the Y Chromosome," American Journal of Human Genetics 68 (2001): 1485-1496.

(34.) Alan G Fix, "Colonization Models and Initial Genetic Diversity in the Americas," Human Biology 74:1 (Feb 2002): 1-10.

(35.) Lyle Campbell, American Indian Languages. This Historical Linguistics of Native America (New York, 1997), chapter 3.

(36.) Joseph F. Powell & Walter A. Neves, "Craniofacial Morphology of the First Americans: Pattern and Process in the Peopling of the New World," Yearbook of Physical Anthropology 42 (1999): 153-188.

(37.) See Joseph F. Powell and Walter A. Neves, "Dental diversity of early New World populations: Taking a bite out of the tripartite model," American Journal of Physical Anthropolgy 105 (1998) (Issue S 26): 179-180; as well their broad survey in Powell & Neves, "Craniofacial Morphology."

Herbert S. Klein

Columbia University

Department of History

New York, NY 10027

Daniel C. Schiffner

University of California, San Francisco

School of Medicine

San Francisco, CA 94143