Ancient History/Human Evolution/Recent African Origin

Introduction thumb|right|350px|One model of human migration based on Mitochondrial DNA The first theory we will discuss, the recent African origin of modern humans, frequently dubbed the "Out of Africa" theory, is the most widely accepted model describing the origin and early dispersal of anatomically modern humans.William A. Haviland Harald E. L. Prins Dana Walrath Bunny McBride The Essence of Anthropology http://books.google.com/books?id=AmvJ1XtnIQoC&pg=PA90 14 June 2011 24 February 2009 Cengage Learning 9780495599814 90 The theory is called the (Recent) Out-of-Africa model in the popular press, and academically the recent single-origin hypothesis (RSOH), Replacement Hypothesis, and Recent African Origin (RAO) model. The hypothesis that humans have a single origin (monogenesis) was published in Charles Darwin's Descent of Man (1871). The concept was speculative until the 1980s, when it was corroborated by a study of present-day mitochondrial DNA, combined with evidence based on physical anthropology of archaic specimens. The theory is based on genetic and fossil evidence, which is interpreted to show that archaic Homo sapiens evolved to anatomically modern humans solely in Africa, between 200,000 and 150,000 years ago,Renée Hetherington Robert G. B. Reid The Climate Connection: Climate Change and Modern Human Evolution http://books.google.com/books?id=AAja8FTPF6QC&pg=PA64 14 June 2011 2010 Cambridge University Press 9780521147231 64 that members of one branch of Homo sapiens left Africa by between 125,000 and 60,000 years ago, and that over time these humans replaced earlier human populations such as Neanderthals and Homo erectus.Martin Meredith Born in Africa: The Quest for the Origins of Human Life http://books.google.com/books?id=WrR9OShae2wC&pg=PT148 14 June 2011 10 May 2011 PublicAffairs 9781586486631 148 The date of the earliest successful "out of Africa" migration (earliest migrants with living descendents) has generally been placed at 60,000 years ago as suggested by genetics, although attempts at migration out of the continent may have taken place as early as 125,000 years ago according to Arabian archaeology finds of tools in the region., 331 (6016), 453-456 DOI: 10.1126/science.1199113 The recent single origin of modern humans in East Africa is the predominant position held within the scientific community. Liu H, Prugnolle F, Manica A, Balloux F A geographically explicit genetic model of worldwide human-settlement history Am. J. Hum. Genet. 79 2 230–7 2006 August 16826514 1559480 10.1086/505436 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. http://www.sciencemag.org/cgi/content/summary/sci;308/5724/921g Out of Africa Revisited – 308 (5724): 921g – Science 10.1126/science.308.5724.921g Sciencemag.org 2005-05-13 2009-11-23 Stringer C Human evolution: Out of Ethiopia Nature 423 6941 692–3, 695 2003 June 12802315 10.1038/423692a http://www.actionbioscience.org/evolution/johanson.html Origins of Modern Humans: Multiregional or Out of Africa? Johanson D ActionBioscience American Institute of Biological Sciences http://www.asa3.org/ASA/education/origins/migration.htm Modern Humans – Single Origin (Out of Africa) vs Multiregional There are differing theories on whether there was a single exodus or several. A multiple dispersal model involves the Southern Dispersal theory,Searching for traces of the Southern Dispersal, by Dr. Marta Mirazón Lahr, et al. which has gained support in recent years from genetic, linguistic and archaeological evidence. A growing number of researchers also suspect that "long-neglected North Africa", was the original home of the modern humans who first trekked out of the continent.Was North Africa the Launch Pad for Modern Human Migrations? Michael Balter, science 7 January 2011: 331 (6013), 20–23. [DOI:10.1126/science.331.6013.20]A Revised Root for the Human Y Chromosomal Phylogenetic Tree: The Origin of Patrilineal Diversity in Africa. Fulvio Cruciani, Beniamino Trombetta, Andrea Massaia, Giovanni Destro-Bisol, Daniele Sellitto, Rosaria Scozzari, The American Journal of Human Genetics – 19 May 2011Earliest evidence of modern human life history in North African early Homo sapiens, Tanya M. Smith, Paul Tafforeau, Donald J. Reid, Rainer Grün, Stephen Eggins, Mohamed Boutakiout, Jean-Jacques Hublin, doi: 10.1073/pnas.0700747104 PNAS April 10, 2007 vol. 104 no. 15 6128–6133 The major competing hypothesis is the multiregional origin of modern humans, which envisions a wave of Homo sapiens migrating from Africa and interbreeding with local Homo erectus populations in multiple regions of the globe. Most multiregionalists still view Africa as a major wellspring of human genetic diversity, but allow a much greater role for hybridization.Robert Jurmain Lynn Kilgore Wenda Trevathan Essentials of Physical Anthropology http://books.google.com/books?id=TSaSPza9LMYC&pg=PA266 14 June 2011 20 March 2008 Cengage Learning 9780495509394 266–10766948 10.1002/(SICI)1096-8644(200005)112:1<129::AID-AJPA11>3.0.CO;2-K This theory will be discussed in the next section. History of the theory thumb|Haeckel's Paleontological Tree of Vertebrates (c. 1879).The evolutionary history of species has been described as a "tree", with many branches arising from a single trunk. While Haeckel's tree is somewhat outdated, it illustrates clearly the principles that more complex modern reconstructions can obscure. With the development of anthropology in the early 19th century, scholars disagreed vigorously about different theories of human development. Those such as Johann Friedrich Blumenbach and James Cowles Pritchard held that since the creation, the various human races had developed as different varieties sharing descent from one people (monogenism). Their opponents, such as Louis Agassiz and Josiah C. Nott, argued for polygenism, or the separate development of human races as separate species or had developed as separate species through transmutation of species from apes, with no common ancestor. Charles Darwin was one of the first to propose common descent of living organisms, and among the first to suggest that all humans had in common ancestors who lived in Africa.Peter Lafreniere Adaptive Origins: Evolution and Human Development http://books.google.com/books?id=3F-Ms0mWKVYC&pg=PA90 14 June 2011 22 September 2010 Taylor & Francis 9780805860122 90 In the Descent of Man, he speculated that humans had descended from apes which still had small brains but walked upright, freeing their hands for uses which favoured intelligence. Further, he thought such apes were African:Bowler 2003 213 In each great region of the world the living mammals are closely related to the extinct species of the same region. It is, therefore, probable that Africa was formerly inhabited by extinct apes closely allied to the gorilla and chimpanzee; and as these two species are now man's nearest allies, it is somewhat more probable that our early progenitors lived on the African continent than elsewhere. But it is useless to speculate on this subject, for an ape nearly as large as a man, namely the Dryopithecus of Lartet, which was closely allied to the anthropomorphous Hylobates, existed in Europe during the Upper Miocene period; and since so remote a period the earth has certainly undergone many great revolutions, and there has been ample time for migration on the largest scale. Charles Darwin Descent of Manhttp://darwin-online.org.uk/content/frameset?viewtype=text&itemID=F937.1&pageseq=212 The descent of man Chapter 6 – On the Affinities and Genealogy of Man Darwin-online.org.uk 2011-01-11 The prediction was insightful, because in 1871 there were hardly any human fossils of ancient hominids available. Almost fifty years later, Darwin's speculation was supported when anthropologists began finding numerous fossils of ancient small-brained hominids in several areas of Africa (list of hominina fossils). The debate in anthropology had swung in favour of monogenism by the mid-20th century. Isolated proponents of polygenism held forth in the mid-20th century, such as Carleton Coon, who hypothesized as late as 1962 that Homo sapiens arose five times from Homo erectus in five places.Jackson Jr., John P. (2001). "In Ways Unacademical": The Reception of Carleton S. Coon's The Origin of Races, University of Colorado The "Recent African origin" of modern humans means "single origin" (monogenism) and has been used in various contexts as an antonym to polygenism. In the 1980s Allan Wilson togather with Rebecca Cann and Mark Stoneking on the so-called "Mitochondrial Eve" hypothesis. In his efforts to identify informative genetic markers for tracking human evolutionary history, he started to focus on mitochondrial DNA (mtDNA) — genes that sit in the cell, but not in the nucleus, and are passed from mother to child. This DNA material is important because it mutates quickly, thus making it easy to plot changes over relatively short time spans. By comparing differences in the mtDNA Wilson believed it was possible to estimate the time, and the place, modern humans first evolved. With his discovery that human mtDNA is genetically much less diverse than chimpanzee mtDNA, he concluded that modern human races had diverged recently from a single population while older human species such as Neandertal and Homo erectus had become extinct. He and his team compared mtDNA in people of different racial backgrounds and concluded that all modern humans evolved from one 'lucky mother' in Africa about 150,000 years ago.Allan Wilson, REVOLUTIONARY EVOLUTIONIST With the advent of archaeogenetics in the 1990s, scientists were able to date the "out of Africa" migration with some confidence. In 2000, the mitochondrial DNA (mtDNA) sequence of "Mungo Man 3" (LM3) of ancient Australia was published indicating that Mungo Man was an extinct subspecies that diverged before the most recent common ancestor of contemporary humans. The results, if correct, supports the multiregional origin of modern humans hypothesis. Adcock GJ, Dennis ES, Easteal S, Huttley GA, Jermiin LS, Peacock WJ, Thorne A Mitochondrial DNA sequences in ancient Australians: Implications for modern human origins Proc. Natl. Acad. Sci. U.S.A. 98 2 537–42 2001 January 11209053 14622 10.1073/pnas.98.2.537 2001PNAS...98..537A Australia Challenges Out-of-Africa Theory ABC News January 9, 2003 This work was later questioned Cooper A, Rambaut A, Macaulay V, Willerslev E, Hansen AJ, Stringer C Human origins and ancient human DNA Science 292 5522 1655–6 2001 June 11388352 10.1126/science.292.5522.1655 The thermal history of human fossils and the likelihood of successful DNA amplification 10.1016/S0047-2484(03)00106-4 http://www.eva.mpg.de/evolution/staff/c_smithpdf/Smith_et_al_Therma_ageJHE03.pdf PDF 2003 Chamberlain, C Journal of Human Evolution 45 203–17 14580590 Chamberlain AT Riley MS Stringer C Collins MJ 3 and explained by W. James Peacock, leader of the team who sequenced Mungo man's ancient mtdna.Jon Schiller Human Evolution: Neanderthals & Homosapiens http://books.google.com/books?id=3Huo_r-w2WcC&pg=PA66 29 November 2011 1 April 2010 CreateSpace 978-1-4515-4608-8 66 The question of whether there was inheritance of other typological (not de facto) Homo subspecies into the Homo sapiens genetic pool is debated. Early Homo sapiens thumb|left|Anatomical comparison of the skulls of a modern human (left) and Homo neanderthalensis (right). Anatomically modern humans originated in Africa about 250,000 years ago. The trend in cranial expansion and the acheulean elaboration of stone tool technologies which occurred between 400,000 years ago and the second interglacial period in the Middle Pleistocene (around 250,000 years ago) provide evidence for a transition from H. erectus to H. sapiens.Eric Delson Ian Tattersall John A. Van Couvering Encyclopedia of human evolution and prehistory http://books.google.com/books?id=E8z9YZZiKHgC&pg=PA677 14 June 2011 2000 Taylor & Francis 9780815316961 677– In the Recent African Origin (RAO) scenario, migration within and out of Africa eventually replaced the earlier dispersed H. erectus. Homo sapiens idaltu, found at site Middle Awash in Ethiopia, lived about 160,000 years ago. White TD, Asfaw B, DeGusta D, Gilbert H, Richards GD, Suwa G, Howell FC Pleistocene Homo sapiens from Middle Awash, Ethiopia Nature 423 6941 742–7 2003 June 12802332 10.1038/nature01669 It is the oldest known anatomically modern human and classified as an extinct subspecies.160,000-year-old fossilized skulls uncovered in Ethiopia are oldest anatomically modern humans http://www.berkeley.edu/news/media/releases/2003/06/11_idaltu.shtml University of California, Berkeley 2003 Fossils of early Homo sapiens were found in Qafzeh cave in Israel and have been dated to 80,000 to 100,000 years ago. However these humans seem to have either become extinct or retreated back to Africa 70,000 to 80,000 years ago, possibly replaced by south bound Neanderthals escaping the colder regions of ice age Europe.Clive Finlayson The humans who went extinct: why Neanderthals died out and we survived http://books.google.com/books?id=EzBV3OPb5mAC&pg=PA68 14 June 2011 11 October 2009 Oxford University Press US 9780199239184 68 Hua Liu & al. analyzing autosomal microsatellite markers dates to c. 56,000±5,700 years ago mtDNA evidence. He interprets the paleontological fossil of early modern human from Qafzeh cave as an isolated early offshoot that retracted back to Africa. Liu H, Prugnolle F, Manica A, Balloux F A geographically explicit genetic model of worldwide human-settlement history Am. J. Hum. Genet. 79 2 230–7 2006 August 16826514 1559480 10.1086/505436 harv All other fossils of fully modern humans outside Africa have been dated to more recent times. The oldest well dated fossils found outside Africa are from Lake Mungo, Australia, and have been dated to about 42,000 years ago. Bowler JM, Johnston H, Olley JM, Prescott JR, Roberts RG, Shawcross W, Spooner NA. New ages for human occupation and climatic change at Lake Mungo, Australia Nature 421 6925 2003 837–40 1259451 10.1038/nature01383 harv Olleya JM, Roberts RG, Yoshida H and Bowler JM Single-grain optical dating of grave-infill associated with human burials at Lake Mungo, Australia Quaternary Science Reviews 25 19–20 2006 2469–2474 10.1016/j.quascirev.2005.07.022 harv 2006QSRv...25.2469O The Tianyuan cave remains in Liujiang region China have a probable date range between 38,000 and 42,000 years ago. They are most similar in morphology to Minatogawa Man, modern humans dated between 17,000 and 19,000 years ago and found on Okinawa Island, Japan. Hu Y, Shang H, Tong H, Nehlich O, Liu W, Zhao C, Yu J, Wang C, Trinkaus E, Richards MP Stable isotope dietary analysis of the Tianyuan 1 early modern human Proc. Natl. Acad. Sci. U.S.A. 106 27 10971–4 2009 July 19581579 2706269 10.1073/pnas.0904826106 harv 2009PNAS..10610971H Brown P Recent human evolution in East Asia and Australasia Philos. Trans. R. Soc. Lond., B, Biol. Sci. 337 1280 235–42 1992 August 1357698 10.1098/rstb.1992.0101 harv However, others have dated Liujang Man to 111,000 to 139,000 years before the present. Shen G, Wang W, Wang Q, Zhao J, Collerson K, Zhou C, Tobias PV U-Series dating of Liujiang hominid site in Guangxi, Southern China J. Hum. Evol. 43 6 817–29 2002 December 12473485 10.1006/jhev.2002.0601 harv Beginning about 100,000 years ago evidence of more sophisticated technology and artwork begins to emerge and by 50,000 years ago fully modern behaviour becomes more prominent. Stone tools show regular patterns that are reproduced or duplicated with more precision while tools made of bone and antler appear for the first time.http://www.handprint.com/LS/ANC/stones.html Ancestral tools Handprint.com 1999-08-01 2011-01-11http://www.wsu.edu/~rquinlan/mptoup.htm Middle to upper paleolithic transition Wsu.edu 2011-01-11 Genetic reconstruction Two pieces of the human genome are quite useful in deciphering human history: mitochondrial DNA and the Y chromosome. These are the only two parts of the genome that are not shuffled about by the evolutionary mechanisms that generate diversity with each generation: instead, these elements are passed down intact. According to the hypothesis, all people alive today have inherited the same Mitochondria Jones, Marie; John Savino Supervolcano: The Catastrophic Event That Changed the Course of Human History (Could Yellowstone be Next?) New Page Books Franklin Lakes, NJ 2007 1-56414-953-6 http://books.google.ca/books?id=tSIa0VQn1NQC&lpg=PA138&dq=all%20%20people%20alive%20today%20have%20inherited%20the%20same%20Mitochondria&pg=PA138#v=onepage&q&f=true from one woman who lived in Africa about 160,000 years ago Cann RL, Stoneking M, Wilson AC Mitochondrial DNA and human evolution Nature 325 6099 31–6 1987 3025745 10.1038/325031a0 harv 1987Natur.325...31C Vigilant L, Stoneking M, Harpending H, Hawkes K, Wilson AC African populations and the evolution of human mitochondrial DNA Science 253 5027 1503–7 1991 September 1840702 10.1126/science.1840702 harv 1991Sci...253.1503V she has been named Mitochondrial Eve. All men today have inherited their Y chromosomes from a man who lived 140,000 years ago, probably in Africa. He has been named Y-chromosomal Adam. It is now believed that more men participated in the out of Africa exodus of early humans than women based on comparing non-sex-specific chromosomes with sex-specific ones. Keinan A, Mullikin JC, Patterson N, Reich D Accelerated genetic drift on chromosome X during the human dispersal out of Africa Nat. Genet. 41 1 66–70 2009 January 19098910 2612098 10.1038/ng.303 harv Mitochondrial DNA thumb|250px|right|Map of early diversification of modern humans according to mitochondrial population genetics (see: Haplogroup L). The first lineage to branch off from Mitochondrial Eve is L0. This haplogroup is found in high proportions among the San of Southern Africa, the Sandawe of East Africa. It is also found among the Mbuti people. Gonder MK, Mortensen HM, Reed FA, de Sousa A, Tishkoff SA Whole-mtDNA genome sequence analysis of ancient African lineages Mol. Biol. Evol. 24 3 757–68 2007 March 17194802 10.1093/molbev/msl209 harv Chen YS, Olckers A, Schurr TG, Kogelnik AM, Huoponen K, Wallace DC mtDNA variation in the South African Kung and Khwe-and their genetic relationships to other African populations Am. J. Hum. Genet. 66 4 1362–83 2000 April 10739760 1288201 10.1086/302848 harv These groups branched off early in human history and have remained relatively genetically isolated since then. Haplogroups L1, L2 and L3 are descendents of L1-6 and are largely confined to Africa. The macro haplogroups M and N, which are the lineages of the rest of the world outside Africa, descend from L3. Y-chromosomal DNA The mutations defining macro-haplogroup CT (all Y haplogroups except A and B) predate the "Out of Africa" migration, its descendent macro-group DE being confined to Africa. The mutations that distinguish Haplogroup C from all other descendants of CR have occurred some 60,000 years ago, shortly after the first Out of Africa migration. Haplogroup F originated some 45,000 years ago, either in North Africa (in which case it would point to a second wave of out-of-Africa migration) or in South Asia. More than 90% of males not native to Africa are descended in direct male line from the first bearer of haplogroup F. Genomic analysis Although mitochondrial DNA and Y-chromosomal DNA are particularly useful in deciphering human history, data on the genomes of dozens of population groups have also been studied. In June 2009, an analysis of genome-wide SNP data from the International HapMap Project (Phase II) and CEPH Human Genome Diversity Panel samples was published. Coop G, Pickrell JK, Novembre J, Kudaravalli S, Li J, Absher D, Myers RM, Cavalli-Sforza LL, Feldman MW, Pritchard JK The role of geography in human adaptation PLoS Genet. 5 6 e1000500 2009 June 19503611 2685456 10.1371/journal.pgen.1000500 harv Schierup Mikkel H. Those samples were taken from 1138 unrelated individuals. Before this analysis, population geneticists expected to find dramatic differences among ethnic groups, with derived alleles shared among such groups but uncommon or nonexistent in other groups. http://www.washingtonpost.com/wp-dyn/content/article/2009/06/21/AR2009062101726_pf.html Among Many Peoples, Little Genomic Variety The Washington Post June 22, 2009 2009-06-25 David Brown Instead the study of 53 populations taken from the HapMap and CEPH data revealed that the population groups studied fell into just three genetic groups: Africans, Eurasians (which includes natives of Europe and the Middle East, and Southwest Asians east to present-day Pakistan), and East Asians, which includes natives of Asia, Japan, Southeast Asia, the Americas, and Oceania. The study determined that most ethnic group differences can be attributed to genetic drift, with modern African populations having greater genetic diversity than the other two genetic groups, and modern Eurasians somewhat more than modern East Asians. The study suggested that natural selection may shape the human genome much more slowly than previously thought, with factors such as migration within and among continents more heavily influencing the distribution of genetic variations. Geography And History Shape Genetic Differences In Humans http://www.sciencedaily.com/releases/2009/06/090605091157.htm Science Daily June 7, 2009 2009-06-25 Movement out of Africa thumb|right|200px|Red Sea crossing By some 70 millennia ago, a part of the bearers of mitochondrial haplogroup L3 migrated from East Africa into the Near East. The date of this first wave of "out of Africa" migration has been called into question in 2011, based on the discovery of stone tools in the United Arab Emirates, indicating the presence of modern humans between 100,000 and 125,000 years ago.http://apnews.myway.com//article/20110127/D9L0V1284.html Humans may have left Africa earlier than thought Apnews.myway.com 2011-06-14 Some scientists believe that only a few people left Africa in a single migration that went on to populate the rest of the world,http://news.softpedia.com/news/Both-Aborigines-and-Europeans-Rooted-in-Africa-54225.shtml Both Australian Aborigines and Europeans Rooted in Africa News.softpedia.com 2011-01-11 based in the fact that only descents of L3 are found outside Africa. From that settlement, some others point to the possibility of several waves of expansion. For example, Wells says that the early travelers followed the southern coastline of Asia, crossed about 250 kilometers [155 miles] of sea, and colonized Australia by around 50,000 years ago. The Aborigines of Australia, Wells says, are the descendants of the first wave of migrations. http://news.bbc.co.uk/2/hi/science/nature/7358868.stm Human line 'nearly split in two' BBC News April 24, 2008 2009-12-31 Paul Rincon It has been estimated that from a population of 2,000 to 5,000 individuals in Africa,2003 et al Zhivotovsky Features of Evolution and Expansion of Modern Humans, Inferred from Genomewide Microsatellite Markers 1180270 72 5 12690579 Rosenberg NA Feldman MW 1171–86 10.1086/375120 American journal of human genetics only a small group, possibly as few as 150 to 1,000 people, crossed the Red Sea.2008 Gary Stix http://www.scientificamerican.com/article.cfm?id=the-migration-history-of-humans The Migration History of Humans: DNA Study Traces Human Origins Across the Continents 2011-06-14 Of all the lineages present in Africa only the female descendants of one lineage, mtDNA haplogroup L3, are found outside Africa. Had there been several migrations one would expect descendants of more than one lineage to be found outside Africa. L3's female descendants, the M and N haplogroup lineages, are found in very low frequencies in Africa (although haplogroup M1 is very ancient and diversified in North and Northeast Africa) and appear to be recent arrivals. A possible explanation is that these mutations occurred in East Africa shortly before the exodus and by the founder effect became the dominant haplogroups after the exodus from Africa. Alternatively, the mutations may have arisen shortly after the exodus from Africa. Other scientists have proposed a Multiple Dispersal Model, in which there were two migrations out of Africa, one across the Red Sea travelling along the coastal regions to India (the Coastal Route), which would be represented by Haplogroup M. Another group of migrants with Haplogroup N followed the Nile from East Africa, heading northwards and crossing into Asia through the Sinai. This group then branched in several directions, some moving into Europe and others heading east into Asia. This hypothesis attempts to explain why Haplogroup N is predominant in Europe and why Haplogroup M is absent in Europe. Evidence of the coastal migration is hypothesized to have been destroyed by the rise in sea levels during the Holocene epoch.http://www.biomedcentral.com/1471-2156/2/13/comments/comments A single origin, several dispersal hypothesis Biomedcentral.com 2004-10-29 2011-01-11 Alternatively, a small European founder population that initially expressed both Haplogroup M and N could have lost Haplogroup M through random genetic drift resulting from a bottleneck (i.e. a founder effect). Today at the Bab-el-Mandeb straits the Red Sea is about 12 miles (20 kilometres) wide, but 50,000 years ago sea levels were 70 meters lower (owing to glaciation) and the water was much narrower. Though the straits were never completely closed, there may have been islands in between which could be reached using simple rafts. Shell middens 125,000 years old have been found in Eritrea, Walter RC, Buffler RT, Bruggemann JH, Guillaume MM, Berhe SM, Negassi B, Libsekal Y, Cheng H, Edwards RL, von Cosel R, Néraudeau D, Gagnon M Early human occupation of the Red Sea coast of Eritrea during the last interglacial Nature 405 6782 65–9 2000 May 10811218 10.1038/35011048 harv indicating the diet of early humans included seafood obtained by beachcombing. Subsequent expansion thumb|320px|Map of early human migrationsLiterature: Göran Burenhult: Die ersten Menschen, Weltbild Verlag, 2000. 3-8289-0741-51. Homo sapiens2. Neanderthals3. Early Hominids From the Near East, these populations spread east to South Asia by 50,000 years ago, and on to Australia by 40,000 years ago, Homo sapiens for the first time colonizing territory never reached by Homo erectus. Europe was reached by Cro-Magnon some 40,000 years ago. East Asia (Korea, Japan) was reached by 30,000 years ago. It is disputed whether subsequent migration to North America took place around 30,000 years ago, or only considerably later, around 14,000 years ago. The group that crossed the Red Sea travelled along the coastal route around the coast of Arabia and Persia until reaching India, which appears to be the first major settling point. M is found in high frequencies along the southern coastal regions of Pakistan and India and it has the greatest diversity in India, indicating that it is here where the mutation may have occurred. Metspalu M, Kivisild T, Metspalu E, Parik J, Hudjashov G, Kaldma K, Serk P, Karmin M, Behar DM, Gilbert MT, Endicott P, Mastana S, Papiha SS, Skorecki K, Torroni A, Villems R Most of the extant mtDNA boundaries in south and southwest Asia were likely shaped during the initial settlement of Eurasia by anatomically modern humans BMC Genet. 5 26 2004 August 15339343 516768 10.1186/1471-2156-5-26 harv Sixty percent of the Indian population belong to Haplogroup M. The indigenous people of the Andaman Islands also belong to the M lineage. The Andamanese are thought to be offshoots of some of the earliest inhabitants in Asia because of their long isolation from mainland Asia. They are evidence of the coastal route of early settlers that extends from India along the coasts of Thailand and Indonesia all the way to Papua New Guinea. Since M is found in high frequencies in highlanders from New Guinea as well, and both the Andamanese and New Guineans have dark skin and Afro-textured hair, some scientists believe they are all part of the same wave of migrants who departed across the Red Sea ~60,000 years ago in the Great Coastal Migration. Notably, the findings of Harding et al. (2000, p. 1355) show that, at least with regard to dark skin color, the haplotype background of Papua New Guineans at MC1R (one of a number of genes involved in melanin production) is identical to that of Africans (barring a single silent mutation). Thus, although these groups are distinct from Africans at other loci (due to drift, bottlenecks, etc.), it is evident that selection for the dark skin color trait likely continued (at least at MC1R) following the exodus. This would support the hypothesis that suggests that the original migrants from Africa resembled pre-exodus Africans (at least in skin color), and that the present day remnants of this ancient phenotype can be seen among contemporary Africans, Andamanese and New Guineans. Others suggest that their physical resemblance to Africans could be the result of convergent evolution.http://ehl.santafe.edu/ruhlen.htm Evolution of Human Languages Ehl.santafe.edu 2011-01-11 Endicott P, Gilbert MT, Stringer C, Lalueza-Fox C, Willerslev E, Hansen AJ, Cooper A The genetic origins of the Andaman Islanders Am. J. Hum. Genet. 72 1 178–84 2003 January 12478481 378623 10.1086/345487 From Arabia to India the proportion of haplogroup M increases eastwards: in eastern India, M outnumbers N by a ratio of 3:1. However, crossing over into East Asia, Haplogroup N reappears as the dominant lineage. M is predominant in South East Asia but amongst Indigenous Australians N reemerges as the more common lineage. This discontinuous distribution of Haplogroup N from Europe to Australia can be explained by founder effects and population bottlenecks. Ingman M, Gyllensten U Mitochondrial genome variation and evolutionary history of Australian and New Guinean aborigines Genome Res. 13 7 1600–6 2003 July 12840039 403733 10.1101/gr.686603 harv Competing hypotheses The multiregional hypothesis, initially proposed by Milford Wolpoff, holds that the evolution of humans from H. erectus at the beginning of the Pleistocene 1.8 million years BP to the present day has been within a single, continuous worldwide population. Proponents of multiregional origin reject the assumption of an infertility barrier between ancient Eurasian and African populations of Homo. Multiregional proponents point to the fossil record and genetic evidence in chromosomal DNA. One study suggested that at least 5% of the human modern gene pool can be attributed to ancient admixture, which in Europe would be from the Neanderthals. Plagnol V, Wall JD Possible ancestral structure in human populations PLoS Genet. 2 7 e105 2006 July 16895447 1523253 10.1371/journal.pgen.0020105 ..strong evidence for ancient admixture in both a European and a West African population (p ≈ 10−7), with contributions to the modern gene pool of at least 5%. While Neanderthals form an obvious archaic source population candidate in Europe.. harv But the study also suggests that there may be other reasons why humans and Neanderthals share ancient genetic lineages. Green RE, Krause J, Briggs AW, et al. A draft sequence of the Neandertal genome Science 328 5979 710–22 2010 May 20448178 10.1126/science.1188021 http://news.bbc.co.uk/2/hi/science/nature/8660940.stm BBC News 2010Sci...328..710G Blum MG, Jakobsson M Deep divergences of human gene trees and models of human origins Mol. Biol. Evol. 28 2 889–98 2010 October 20930054 10.1093/molbev/msq265 The strong form of the theory has been further challenged by recent genetic discoveries regarding the non-Homo sapiens Denisova hominin, known from only one sample in Siberia. The sample was found to share 4–6% genetic affinities with modern Melanesians, but not with other extant groups, making hybridisation in Africa very unlikely in this case.Reich, David; Green, Richard E.; Kircher, Martin; Krause, Johannes; Patterson, Nick; Durand, Eric Y.; Viola, Bence; Briggs, Adrian W. et al. (2010), "Genetic history of an archaic hominin group from Denisova Cave in Siberia", Nature 468 (7327): 1053–1060, doi:10.1038/nature09710 Other hypotheses see the emergence of Homo erectus outside Africa (in Eurasia)"Homo erectus". Encyclopaedia Britannica. and then returning to colonize that continent from which H. erectus's ancestors originated."How Man Began". Time."Planet of the Apes". Scientific American. "Dispersal patterns of Eurasian hominoids: implications from Turkey". David R. Begun, Erksin Güleç & Denis Geraads. References