Fences and windows (talk | contribs) →Fossil evidence: Moving genetic evidence |
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==Genetic evidence== |
==Genetic evidence== |
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Proponents of the multiregional or hybrid-origin hypothesis point to the study of temporally separated genetic lineages on the scale of 1MYA, and interpret it as genetic evidence for inter-breeding between 'humans' and other 'hominids'.{{Clarify me|date=May 2009}} |
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Studies on past [[population bottleneck]]s that can be inferred from molecular data have led multiregionalists to conclude that the recent single-origin hypothesis is untenable because there are no population size bottlenecks affecting all genes that are more recent than 2 million years ago. |
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*[[Microcephalin]].<ref>Evidence that the adaptive allele of the brain size gene microcephalin introgressed into Homo sapiens from an archaic Homo lineage; PNAS | November 28, 2006 | vol. 103 | no. 48 | 18178-18183 ; quote: "... As such, microcephalin shows by far the most compelling evidence of admixture among the human loci examined thus far. Speculation about the identity of the archaic Homo population from which the microcephalin D allele introgressed into the modern human gene pool '''points to the Neanderthal lineage''' as a potential (although by no means only) candidate. Anatomically modern humans and Neanderthals shared a long period of coexistence, from as early as 130,000 years ago in the Middle East (39) to as late as 35,000 years ago in Europe (40), consistent with the estimated introgression time of the microcephalin D allele at or sometime before {approx}37,000 years ago. Furthermore, the worldwide frequency distribution of the D allele, exceptionally high outside of Africa but low in sub-Saharan Africa (29), suggests, but does not necessitate, admixture with an archaic Eurasian population. Finally, our estimate of the separation time between D and non-D alleles (i.e., {approx}1,100,000 years with a lower-bound confidence interval of {approx}530,000 years) is largely consistent with the divergence time between modern humans and Neanderthals based on mitochondrial DNA (mtDNA) sequence difference (320,000–740,000 years; refs. 41 and 42) and with the earliest appearance of Neanderthals in the fossil record {approx}500,000 years ago (43). It would be of great interest to sequence the microcephalin locus in Neanderthals or other archaic Homo lineages, should it become technically feasible to retrieve and analyze nuclear DNA from ancient hominid remains. Our results not only provide genetic evidence in support of the possibility of admixture between modern humans and an archaic Homo lineage but also support the notion that the biological evolution of modern humans might have benefited from the contribution of adaptive alleles from our archaic relatives. In the case of microcephalin, it is all the more intriguing given the fact that the adaptive allele is associated with an important brain development gene. ..." URL:http://www.pnas.org/cgi/content/full/103/48/18178</ref><ref>http://www.pnas.org/cgi/content/full/104/18/7367</ref><ref>Microcephalin, a Gene Regulating Brain Size, Continues to Evolve Adaptively in Humans; Science 9 September 2005: Vol. 309. no. 5741, pp. 1717 - 1720 DOI: 10.1126/science.1113722; Patrick D. Evans & all; URL:http://www.sciencemag.org/cgi/content/full/309/5741/1717 </ref> |
*[[Microcephalin]].<ref>Evidence that the adaptive allele of the brain size gene microcephalin introgressed into Homo sapiens from an archaic Homo lineage; PNAS | November 28, 2006 | vol. 103 | no. 48 | 18178-18183 ; quote: "... As such, microcephalin shows by far the most compelling evidence of admixture among the human loci examined thus far. Speculation about the identity of the archaic Homo population from which the microcephalin D allele introgressed into the modern human gene pool '''points to the Neanderthal lineage''' as a potential (although by no means only) candidate. Anatomically modern humans and Neanderthals shared a long period of coexistence, from as early as 130,000 years ago in the Middle East (39) to as late as 35,000 years ago in Europe (40), consistent with the estimated introgression time of the microcephalin D allele at or sometime before {approx}37,000 years ago. Furthermore, the worldwide frequency distribution of the D allele, exceptionally high outside of Africa but low in sub-Saharan Africa (29), suggests, but does not necessitate, admixture with an archaic Eurasian population. Finally, our estimate of the separation time between D and non-D alleles (i.e., {approx}1,100,000 years with a lower-bound confidence interval of {approx}530,000 years) is largely consistent with the divergence time between modern humans and Neanderthals based on mitochondrial DNA (mtDNA) sequence difference (320,000–740,000 years; refs. 41 and 42) and with the earliest appearance of Neanderthals in the fossil record {approx}500,000 years ago (43). It would be of great interest to sequence the microcephalin locus in Neanderthals or other archaic Homo lineages, should it become technically feasible to retrieve and analyze nuclear DNA from ancient hominid remains. Our results not only provide genetic evidence in support of the possibility of admixture between modern humans and an archaic Homo lineage but also support the notion that the biological evolution of modern humans might have benefited from the contribution of adaptive alleles from our archaic relatives. In the case of microcephalin, it is all the more intriguing given the fact that the adaptive allele is associated with an important brain development gene. ..." URL:http://www.pnas.org/cgi/content/full/103/48/18178</ref><ref>http://www.pnas.org/cgi/content/full/104/18/7367</ref><ref>Microcephalin, a Gene Regulating Brain Size, Continues to Evolve Adaptively in Humans; Science 9 September 2005: Vol. 309. no. 5741, pp. 1717 - 1720 DOI: 10.1126/science.1113722; Patrick D. Evans & all; URL:http://www.sciencemag.org/cgi/content/full/309/5741/1717 </ref> |
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*RRM2P4 region on [[X chromosome]].<ref>''Testing for Archaic Hominin Admixture on the X Chromosome: Model Likelihoods for the Modern Human RRM2P4 Region From Summaries of Genealogical Topology Under the Structured Coalescent''. Murray P. Cox Genetics, Vol. 178, 427-437, January 2008, doi:10.1534/genetics.107.080432 URL: http://www.genetics.org/cgi/content/full/178/1/427</ref> |
*RRM2P4 region on [[X chromosome]].<ref>''Testing for Archaic Hominin Admixture on the X Chromosome: Model Likelihoods for the Modern Human RRM2P4 Region From Summaries of Genealogical Topology Under the Structured Coalescent''. Murray P. Cox Genetics, Vol. 178, 427-437, January 2008, doi:10.1534/genetics.107.080432 URL: http://www.genetics.org/cgi/content/full/178/1/427</ref> |
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*PDHA1 locus on X chromosome.<ref>More on the X files. Rosalind M. Harding. PNAS Vol. 96, Issue 6, 2582-2584, March 16, 1999 http://www.pnas.org/cgi/content/full/96/6/2582; quote:''the pattern of diversity at the PDHA1 locus unexpected is that this extreme structure is observed in a polymorphism with an estimated total coalescent-time depth of 1.86 million years''</ref> |
*PDHA1 locus on X chromosome.<ref>More on the X files. Rosalind M. Harding. PNAS Vol. 96, Issue 6, 2582-2584, March 16, 1999 http://www.pnas.org/cgi/content/full/96/6/2582; quote:''the pattern of diversity at the PDHA1 locus unexpected is that this extreme structure is observed in a polymorphism with an estimated total coalescent-time depth of 1.86 million years''</ref> |
Revision as of 21:04, 29 May 2009
The multiregional hypothesis is a theory of the origin of anatomically modern humans, Homo sapiens sapiens. The multiregional hypothesis holds that the evolution of humanity throughout the Pleistocene (1.8 million years ago till today) has been within a single, continuous human species, evolving worldwide from Homo erectus to modern Homo sapiens.[1]
A competing theory of the recent African origin of modern humans (also known as "Out of Africa") has emerged as the near consensus view since the 1990s,[2][3] proposing that modern humans arose in Africa around 100-200,000 years ago, moving out of Africa around 50-60,000 years ago to replace existing human species such as Homo erectus and the Neanderthals.[4]
Advocates of the multiregional hypothesis point to some recent genetic data^[5] as support for their hypothesis, and some interbreeding (or "admixture") between modern humans and previous human species has not been ruled out,[6][7] although it is increasingly unlikely for Neanderthals.[8][9] To differentiate the current theory from earlier unscientific theories some researchers prefer the term multiregional evolution.
History
Polygenism
An older theory is polygenic evolution, a multiple origins theory in which the different human populations or races had independent origins and evolved in isolation from each other. It was held by many scholars of the 19th century such as Haeckel and Klaatsch. Polygenism is sometimes mistaken for multiregional evolution, because they are both hypotheses of evolution within a single species. However, polygenic evolution depends on isolation of populations while multiregional evolution requires population interactions and interbreeding so that genetic changes can spread throughout the human range, especially when they are promoted by natural selection. According to the multiregional hypothesis, geographic differences between human populations are the results of climatic variation, isolation by distance, sexual selection, and historical accidents (genetic drift).
Weidenreich-Coon
The multiregional hypothesis has its origin in the work of Franz Weidenreich in the 1930s. At that time, Weidenreich originated the "Weidenreich Theory of Human Evolution" based on his examination of Peking Man. Weidenreich was an anatomist and observed numerous anatomical characteristics that he thought Peking Man had in common with modern Asians. The Weidenreich Theory stated that human races have evolved independently in the Old World from Homo erectus to Homo sapiens sapiens, while at the same time there was gene flow between the various populations. According to the theory proposed by Weidenreich, genes that were generally adaptive (such as those for intelligence) flowed relatively rapidly from one part of the world to the other, while those that were locally adaptive, would not. A vocal proponent of the Weidenreich theory was Carleton Coon.
Regional continuity
The term "multiregional hypothesis" was first coined in the early 1980s by Milford H. Wolpoff and a group of associates as an explanation for the apparent similarities of the remains from the Homo erectus and Homo sapiens inhabiting the same region, what they called regional continuity.
Wolpoff proposed an explanation based on clinal variation that would allow for the necessary balance. He proposed that Homo erectus, Neanderthals, Homo sapiens and other humans were a single species. This species arose in Africa two million years ago as H. erectus and then spread out over the world, developing adaptations to regional conditions. It was proposed that for periods of time some populations became isolated, developing in a different direction, but through continuous interbreeding, replacement, genetic drift and other vehicles of evolution, adaptations that were an advantage anywhere on earth would spread, keeping the development of the species in the same overall direction, while maintaining adaptations to regional factors. Eventually, the more unusual local varieties of the species would have disappeared in favor of modern humans while retaining some regional adaptations, but also with many common features.
Fossil evidence
Multiregionalists claimed that the discovery of a possible hybrid Homo sapiens X neanderthalensis fossil child at the Abrigo do Lagar Velho rock-shelter site in Portugal in 1999 further supports the multiregional hypothesis, by reflecting the admixture of diverse human populations[10]. Two other archaeologists dispute this: "the analysis by Duarte et al. of the Lagar Velho child's skeleton is a brave and imaginative interpretation, of which it is unlikely that a majority of paleoanthropologists will consider proven."[11]
In an article appearing in the Proceedings of the National Academy of Sciences[12] in 2007, Erik Trinkaus has brought together the available data, which shows that early modern humans did exhibit evidence of Neandertal traits. "When you look at all of the well dated and diagnostic early modern European fossils, there is a persistent presence of anatomical features that were present among the Neandertals but absent from the earlier African modern humans," Trinkaus said. "Early modern Europeans reflect both their predominant African early modern human ancestry and a substantial degree of admixture between those early modern humans and the indigenous Neandertals." [13]
A recent, non-fossilized discovery of one metre-tall, small-brained (350 cc), Homo floresiensis, on the Indonesian island of Flores, might imply populations of Homo erectus survived very late, and gave rise to even later, physically dwarfed isolated "erectus" groups. However, this possibility does not address the multiregional hypothesis, which is only about the human species, and the evidence is marred by the possibility that the single dwarf cranium found on Flores might have been pathological.[original research?]
Genetic evidence
Studies on past population bottlenecks that can be inferred from molecular data have led multiregionalists to conclude that the recent single-origin hypothesis is untenable because there are no population size bottlenecks affecting all genes that are more recent than 2 million years ago.
- Microcephalin.[14][15][16]
- RRM2P4 region on X chromosome.[17]
- PDHA1 locus on X chromosome.[18]
Researchers
The most prominent current proponents of the multiregional hypothesis are Milford H. Wolpoff, Wu Xinzhi, Alan G. Thorne, James Calcagno[19], John Hawks[20], Alan Templeton, and Erik Trinkaus.
Hybrid-origin theory
The hybrid-origin hypothesis of human origins argues that all or at least some of the genetic variation between the contemporary human races is attributable to genetic inheritance from at least two widely divergent hominid species, or subspecies, that were geographically dispersed throughout Africa, Southeast Asia and the Indian subcontinent, prior to the evolution of modern Homo sapiens sapiens (according to hybrid-origin theory, approximately 35,000 years ago). Hominid populations, put forward by the hybrid-origin theory as sources for genetic admixture, include Homo neanderthalensis and Peking Man. According to this theory the resulting hybrid 'Homo sapiens sapiens', was superior to both its ancestors due to what is commonly termed hybrid vigour. This theory was first introduced in 1971 by the British psychologist Stan Gooch.[21]
Criticism of the multiregional hypothesis
Multiregional evolution contrasts with the "Recent African Origin" (RAO) theory. According to the latter theory, human evolution was a consequence of many cases of species replacement, as newer species replaced older ones across the human range. Modern human origins, according to the RAO, is the most recent example of species replacement.
Aspects of multiregionalism have been criticized as not being based on objective scientific observation. Some critics even argue that multiregionalism may be motivated by ethnocentrism and is meant to instill beliefs of purity of lineage.
Multiregionalists have long claimed that modern Europeans are descended from the Neanderthals. In 1997, testing performed on mitochondrial DNA extracted from a Neanderthal skeleton showed modern humans and Neanderthals last shared a common ancestor between 500,000 and 800,000 years ago, and furthermore that all modern humans, from the ethnic Siberians to the !Kung people of Africa, are more closely related to each other than to the Neanderthals -- further evidence supporting the Out-of-Africa theory[citation needed]. But ancient lineages, dating to over 1 Mya, in nuclear DNA has been detected (see genetic evidence above).[clarification needed]
Peking man (also known as "Beijing man"), a Homo erectus fossil skull (possibly dated to 500,000 years ago) found in China, provides putative evidence supporting the Multiregional Theory. Some paleoanthropologists in China have asserted that the modern Chinese are descendants of earlier forms of humans such as Peking Man. However criticism is based on genetic evidence from mtDNA. Microsatellite analysis on the Chinese populations in 1998 showed genetic similarities with Africans, yielding the first evidence the Chinese population is matrilineal from Africa.[22] A recent study undertaken by Jin Li showed no inter-breeding between modern human immigrants to East Asia and Homo erectus, contradicting the Peking Man-origin hypothesis and affirming that the Chinese descended from Africans.[23][24] In 2001, Chinese geneticists analyzed Y chromosomes in Chinese people and concluded that all Chinese samples contained a mutated gene M168G which is a marker believed to have appeared in the last 79,000 years in an African population.[22]
Implications
Leonard Lieberman and Fatimah Jackson have suggested that any new support for a biological concept of race will likely come from another source, namely, the study of human evolution. They therefore ask what, if any, implications current models of human evolution may have for any biological conception of race.[25]
The major implication for race in the multiregional evolution continuity model involves the time depth of a million or more years in which race differentiation might evolve in diverse ecological regions [...]. This must be balanced against the degree of gene flow and the transregional operation of natural selection on encephalization due to development of tools and, more broadly, culture.[26]
See also
- Polygenism
- Recent single-origin hypothesis
- Punctuated equilibrium
- Interbreeding of Cro-Magnon and Neanderthals
- Mitochondrial Eve
- Y-chromosomal Adam
- Hybrid-origin
References
- ^ Wolpoff, MH (2000). "Multiregional, not multiple origins". Am J Phys Anthropol. 112 (1): 129–36.
{{cite journal}}
: Unknown parameter|coauthors=
ignored (|author=
suggested) (help) - ^ Hua Liu, et al. A Geographically Explicit Genetic Model of Worldwide Human-Settlement History. American Journal of Human Genetics, volume 79 (2006), pages 230–237, quote: Currently available genetic and archaeological evidence is generally interpreted as supportive of a recent single origin of modern humans in East Africa. However, this is where the near consensus on human settlement history ends, and considerable uncertainty clouds any more detailed aspect of human colonization history.
- ^ Weaver, Timothy D (2008). "New developments in the genetic evidence for modern human origins". Evolutionary Anthropology: Issues, News, and Reviews. 17 (1). Wiley-Liss: 69–80.
{{cite journal}}
: Unknown parameter|coauthors=
ignored (|author=
suggested) (help) - ^ Fagundes, NJ (2007). "Statistical evaluation of alternative models of human evolution". Proc Natl Acad Sci U S A. 104 (45): 17614–9.
{{cite journal}}
: Unknown parameter|coauthors=
ignored (|author=
suggested) (help) - ^ Cox, MP (2008). "Testing for archaic hominin admixture on the X chromosome: model likelihoods for the modern human RRM2P4 region from summaries of genealogical topology under the structured coalescent". Genetics. 178 (1): 427–37.
{{cite journal}}
: Unknown parameter|coauthors=
ignored (|author=
suggested) (help) - ^ Relethford, JH (2008). "Genetic evidence and the modern human origins debate". Heredity. 100 (6). Macmillan: 555–63.
- ^ Wall, JD (2006). "Archaic admixture in the human genome". Curr Opin Genet Dev. 16 (6): 606–10.
{{cite journal}}
: Unknown parameter|coauthors=
ignored (|author=
suggested) (help) - ^ Hodgson, JA (2008). "No evidence of a Neanderthal contribution to modern human diversity". Genome Biology. 9 (2). BioMed Central: 206.
{{cite journal}}
: Unknown parameter|coauthors=
ignored (|author=
suggested) (help) - ^ Belle, EM (2009). "Comparing models on the genealogical relationships among Neandertal, Cro-Magnoid and modern Europeans by serial coalescent simulations". Heredity. 102 (3). London: Macmillan: 218–25.
{{cite journal}}
: Unknown parameter|coauthors=
ignored (|author=
suggested) (help) - ^ The early Upper Paleolithic human skeleton from the Abrigo do Lagar Velho (Portugal) and modern human emergence in Iberia ;Duarte C, 2. Maurício J, Pettitt P, Souto P, Trinkaus E, van der Plicht H, Zilhão J (1999) Proc Natl Acad Sci USA 96:7604–7609,[1]
- ^ Chunky Gravettian child; Ian Tattersall and Jeffrey H. Schwartz .[2]
- ^ http://www.pnas.org/cgi/content/abstract/104/18/7367 European early modern humans and the fate of the Neandertals
- ^ http://www.sciencedaily.com/releases/2007/04/070423185434.htm The Emerging Fate Of The Neandertals
- ^ Evidence that the adaptive allele of the brain size gene microcephalin introgressed into Homo sapiens from an archaic Homo lineage; PNAS | November 28, 2006 | vol. 103 | no. 48 | 18178-18183 ; quote: "... As such, microcephalin shows by far the most compelling evidence of admixture among the human loci examined thus far. Speculation about the identity of the archaic Homo population from which the microcephalin D allele introgressed into the modern human gene pool points to the Neanderthal lineage as a potential (although by no means only) candidate. Anatomically modern humans and Neanderthals shared a long period of coexistence, from as early as 130,000 years ago in the Middle East (39) to as late as 35,000 years ago in Europe (40), consistent with the estimated introgression time of the microcephalin D allele at or sometime before {approx}37,000 years ago. Furthermore, the worldwide frequency distribution of the D allele, exceptionally high outside of Africa but low in sub-Saharan Africa (29), suggests, but does not necessitate, admixture with an archaic Eurasian population. Finally, our estimate of the separation time between D and non-D alleles (i.e., {approx}1,100,000 years with a lower-bound confidence interval of {approx}530,000 years) is largely consistent with the divergence time between modern humans and Neanderthals based on mitochondrial DNA (mtDNA) sequence difference (320,000–740,000 years; refs. 41 and 42) and with the earliest appearance of Neanderthals in the fossil record {approx}500,000 years ago (43). It would be of great interest to sequence the microcephalin locus in Neanderthals or other archaic Homo lineages, should it become technically feasible to retrieve and analyze nuclear DNA from ancient hominid remains. Our results not only provide genetic evidence in support of the possibility of admixture between modern humans and an archaic Homo lineage but also support the notion that the biological evolution of modern humans might have benefited from the contribution of adaptive alleles from our archaic relatives. In the case of microcephalin, it is all the more intriguing given the fact that the adaptive allele is associated with an important brain development gene. ..." URL:http://www.pnas.org/cgi/content/full/103/48/18178
- ^ http://www.pnas.org/cgi/content/full/104/18/7367
- ^ Microcephalin, a Gene Regulating Brain Size, Continues to Evolve Adaptively in Humans; Science 9 September 2005: Vol. 309. no. 5741, pp. 1717 - 1720 DOI: 10.1126/science.1113722; Patrick D. Evans & all; URL:http://www.sciencemag.org/cgi/content/full/309/5741/1717
- ^ Testing for Archaic Hominin Admixture on the X Chromosome: Model Likelihoods for the Modern Human RRM2P4 Region From Summaries of Genealogical Topology Under the Structured Coalescent. Murray P. Cox Genetics, Vol. 178, 427-437, January 2008, doi:10.1534/genetics.107.080432 URL: http://www.genetics.org/cgi/content/full/178/1/427
- ^ More on the X files. Rosalind M. Harding. PNAS Vol. 96, Issue 6, 2582-2584, March 16, 1999 http://www.pnas.org/cgi/content/full/96/6/2582; quote:the pattern of diversity at the PDHA1 locus unexpected is that this extreme structure is observed in a polymorphism with an estimated total coalescent-time depth of 1.86 million years
- ^ Calcagno homepage link
- ^ John Hawks homepage link
- ^ Gooch, Guardians of the Ancient Wisdom 1979
- ^ a b 中国人可能起源于非洲又有新证据 (New Evidence Proves that Chinese People Possibly Came from Africa), 大地 2001 No.20, available at People's Daily Online.
- ^ multiregional or single origin.
- ^ mapping human history p130-131
- ^ Leonard Lieberman and Fatimah Linda C. Jackson (1995) "Race and Three Models of Human Origin" in American Anthropologist Vol. 97, No. 2, pp. 232-234
- ^ Leonard Lieberman and Fatimah Linda C. Jackson (1995) "Race and Three Models of Human Origin" in American Anthropologist Vol. 97, No. 2, pp. 237
External links
- New analysis shows three human migrations out of Africa "The 'Out of Africa' replacement theory has always been a big controversy," Templeton said. "I set up a null hypothesis and the program rejected that hypothesis using the new data with a probability level of 10 to the minus 17th. In science, you don't get any more conclusive than that. It says that the hypothesis of no interbreeding is so grossly incompatible with the data, that you can reject it."
- [3] - 'Genomics refutes an exclusively African origin of humans' (pdf) Vinayak Eswaran, Henry Harpending, Alan R. Rogers, Journal of Human Evolution (2005)
- [4] - 'Templeton tree'
- [5] - 'The Hybrid Child from Portugal'
- Biochem. Soc. Trans (2005) 33, 582-585 - J. Hardy and others - Molecular Mechanisms of Neurodegeneration (Evidence suggesting that Homo neanderthalensis contributed the H2 MAPT haplotype to Homo sapiens)
- Kent Holsinger's web site - 'Drift and migration' (only 1 migrant per generation between populations of reasonable big sizes can prevent divergence in allelic frequencies)
- Genetics - 'Deep Haplotype Divergence and Long-Range Linkage Disequilibrium at Xp21.1 Provide Evidence That Humans Descend From a Structured Ancestral Population' (first genetic evidence that statistically rejects the null hypothesis that our species descends from a single, historically panmictic population), Daniel Garrigan, Zahra Mobasher, Sarah B. Kingan, Jason A. Wilder, and Michael F. Hammer, University of Arizona, Tucson, Genetics, Vol. 170, 1849-1856, August 2005
- Linfield.edu - 'The Origin of Modern Humans: Multiregional and Replacement Theories', Michael Roberts, Linfield College
- [6] - 'Evidence for Archaic Asian Ancestry on the Human X Chromosome' (suggests ancient RRM2P4 lineage is remnant of introgressive hybrid of anatomically modern humans from Africa and archaic populations in Eurasia), Daniel Garrigan, Zahra Mobasher, Tesa Severson, Jason A. Wilder, Michael F. Hammer, University of Arizona, Tucson, Molecular Biology and Evolution, vol 22, no 2, p 189-192 (2005)
- PNAS.org - 'Mitochondrial DNA sequences in ancient Australians: Implications for modern human origins', Gregory J. Adcock, Elizabeth S. Dennis, Simon Easteal, Gavin A. Huttley, Lars S. Jermiin, W. James Peacock, Alan Thorne, Australian National University, Proceedings of the National Academy of Sciences, vol 98, no 2, p 537-542 (January 16, 2001)
- StephenJayGould.org - 'Out of Africa vs. Multiregionalism', Tod Billings (December 7, 1999)
- TalkOrigins.org - 'The evolution of modern humans: where are we now?' Christopher B. Stringer, General Anthropology, vol 7, no 2, p 1-5 (2001)
- Selection, nuclear genetic variation, and mtDNA