Temporal range: 0.2–0 Ma Middle Pleistocene–Present
|Male and female H s. sapiens
(Akha in northern Thailand,
Homo sapiens is the systematic name used in taxonomy (also known as binomial nomenclature) for anatomically modern humans, i.e. the only extant human species. The name is Latin for "wise man" and was introduced in 1758 by Carl Linnaeus (who is himself also the type specimen).
Extinct species of the genus Homo are classified as "archaic humans". This includes at least the separate species Homo erectus, and possibly a number of other species (which are variously also considered subspecies of either H. sapiens or H. erectus. H. sapiens idaltu (2003) is a proposed extinct subspecies of H. sapiens.
The age of speciation of H. sapiens out of ancestral H. erectus (or an intermediate species such as Homo heidelbergensis) is estimated to have taken place at roughly 315,000 years ago. However, there is known to have been continued admixture from archaic human species until as late as some 30,000 years ago; this is also the time of disappearance of any surviving archaic human species, which were apparently absorbed by the recent Out-Of-Africa expansion of Homo sapiens beginning some 50,000 years ago.
Name and taxonomy
Extant human populations have historically been divided into subspecies, but since c. the 1980s all extant groups tend to be subsumed into a single species, H. sapiens, avoiding division into subspecies altogether.
Some sources show Neanderthals (Homo neanderthalensis) as a subspecies (Homo sapiens neanderthalensis). Similarly, the discovered specimens of the Homo rhodesiensis species have been classified by some as a subspecies (Homo sapiens rhodesiensis), although it remains more common to treat these last two as separate species within the Homo genus rather than as subspecies within H. sapiens.
Age and speciation process
The speciation of H. sapiens out of varieties of H. erectus is estimated as having taken place between 200,000 and 300,000 years ago. Dispersal of early H. sapiens begins soon after its emergence.
Since the 1970s, the Omo remains, dated to some 195,000 years ago, have often been taken as the conventional cut-off point for the emergence of "anatomically modern humans". Since the 2000s, the discovery of older remains with comparable characteristics, and the discovery of ongoing hybridization between "modern" and "archaic" populations after the time of the Omo remains, have opened up a renewed debate on the "age of Homo sapiens", in journalistic publications cast into terms of "Homo sapiens may be older than previously thought".
A 2017 analysis suggested that the Khoi-San diverged from West African populations as early as 350,000 years ago, i.e. well before the commonly assumed age of H. sapiens. The discovery of fossils attributed to H. sapiens, along with stone tools, dated to approximately 300,000 years ago, found at Jebel Irhoud, Morocco was announced in 2017. Homo sapiens idaltu, found at site Middle Awash in Ethiopia, lived about 160,000 years ago;
Early H sapiens may have reached Asia in a first wave as early as 120,000 years ago. Evidence presented in 2017 raises the possibility that a yet earlier migration, dated to around 270,000 years ago, may have left traces of admixture in Neanderthal genome.
The Recent "Out of Africa" migration of Homo sapiens took place in at least two waves, the first around 130,000 to 100,000 years ago, the second around 70,000 to 60,000 years ago. Eurasia had long been populated by archaic humans, due to the "Out of Africa I" migration more than a million years before. Since the 2010s, admixture events (introgression) of populations of H. sapiens with populations of archaic humans have been discovered as having taken place between roughly 40,000 and 30,000 years ago, both in Eurasia and in Sub-Saharan Africa.
The hypothesis that humans have a single origin (monogenesis) was published in Charles Darwin's Descent of Man (1871). The recent dispersal of H. sapiens from East Africa has been 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 concept had been speculative until the 1980s, and competed with the so-called multiregional origin model. Evidence for the overwhelming contribution of the "recent African origin" of modern populations outside of Africa, due to the wave of expansion beginning after 70,000 years ago, was established based on mitochondrial DNA, combined with evidence based on physical anthropology of archaic specimens, during the 1990s and 2000s. The assumption of complete replacement has been revised in the 2010s with the discovery of limited admixture (of the order of a few percent).
The recent single origin of modern humans in East Africa was the near-consensus position held within the scientific community prior to 2010. The multiregional origin model, proposed by Milford H. Wolpoff in 1988 provides another explanation for the pattern of human evolution. Multiregional origin holds that the evolution of humanity from the beginning of the Pleistocene 2.5 million years BP to the present day has been within a single, continuous human species.
Homo sapiens idaltu, the other known subspecies, is now extinct. Homo neanderthalensis, which became extinct 30,000 years ago, has sometimes been classified as a subspecies, "Homo sapiens neanderthalensis"; genetic studies now suggest that the functional DNA of modern humans and Neanderthals diverged 500,000 years ago.
The San people of Southern Africa have been found to be the human population with the deepest temporal division from all other contemporary populations, estimated at close to 130,000 years ago. A 2011 study has classified them as one of "ancestral population clusters". The same study also located the origin of the first wave of expansion of H. sapiens, beginning roughly 130,000 years ago, in southwestern Africa, near the coastal border of Namibia and Angola.
Following the second Out-of-Africa expansion, some 70,000 to 50,000 years ago, some subpopulations of H. sapiens have been essentially isolated for tens of thousands of years prior to the early modern Age of Discovery. Combined with archaic admixture this has resulted in significant genetic variation, which in some instances has been shown to be the result of directional selection taking place over the past 15,000 years, i.e. significantly later than possible archaic admixture events.
- Global Mammal Assessment Team (2008). "Homo sapiens". The IUCN Red List of Threatened Species. IUCN. 2008: e.T136584A4313662. doi:10.2305/IUCN.UK.2008.RLTS.T136584A4313662.en. Retrieved 12 January 2018.
- Linné, Carl von (1758). Systema naturæ. Regnum animale (10th ed.). pp. 18, 20. Retrieved 19 November 2012..
- The history of claimed or proposed subspecies of H. sapiens is complicated and fraught with controversy. The only widely recognized archaic subspecies is H. sapiens idaltu (2003). The name H. s. sapiens is due to Linnaeus (1758), and refers by definition the subspecies of which Linnaeus himself is the type specimen. However, Linnaeus postulated four other extant subspecies, viz. H. s. afer, H. s. americanus, H. s. asiaticus and H. s. ferus for Africans, Americans, Asians and Malay. This classification remained in common usage until the mid 20th century, sometimes alongide H. s. tasmanianus for Australians. See e.g. John Wendell Bailey, The Mammals of Virginia (1946), p. 356.; Journal of Mammalogy 26-27 (1945), p. 359.; The Mankind Quarterly 1-2 (1960), 113ff ("Zoological Subspecies of Man"). The division of extant human populations into taxonomic subspecies was gradually given up in the 1970s (e.g. Grzimek's Animal Life Encyclopedia, Volume 11, p. 55).
- Hublin, J. J. (2009). "The origin of Neandertals". Proceedings of the National Academy of Sciences. 106 (38): 16022–7. Bibcode:2009PNAS..10616022H. doi:10.1073/pnas.0904119106. JSTOR 40485013. PMC . PMID 19805257.
- Harvati, K.; Frost, S.R.; McNulty, K.P. (2004). "Neanderthal taxonomy reconsidered: implications of 3D primate models of intra- and interspecific differences". Proc. Natl. Acad. Sci. U.S.A. 101 (5): 1147–52. Bibcode:2004PNAS..101.1147H. doi:10.1073/pnas.0308085100. PMC . PMID 14745010.
- "Homo neanderthalensis King, 1864". Wiley-Blackwell Encyclopedia of Human Evolution. Chichester, West Sussex: Wiley-Blackwell. 2013. pp. 328–331.
- Stringer, C. (2012). "What makes a modern human". Nature. 485 (7396): 33–35. doi:10.1038/485033a. PMID 22552077.
- "New Clues Add 40,000 Years to Age of Human Species – NSF – National Science Foundation". www.nsf.gov. "Age of ancient humans reassessed". BBC News. February 16, 2005. Retrieved April 10, 2010. The Oldest Homo Sapiens: – URL retrieved May 15, 2009 Alemseged, Z.; Coppens, Y.; Geraads, D. (2002). "Hominid cranium from Homo: Description and taxonomy of Homo-323-1976-896". Am J Phys Anthropol. 117 (2): 103–12. doi:10.1002/ajpa.10032. PMID 11815945. Stoneking, Mark; Soodyall, Himla (1996). "Human evolution and the mitochondrial genome". Current Opinion in Genetics & Development. 6 (6): 731–6. doi:10.1016/S0959-437X(96)80028-1.
- Schlebusch et al., "Southern African ancient genomes estimate modern human divergence to 350,000 to 260,000 years ago", Science Vol. 358, Issue 6363, (Nov 2017), pp. 652-655, DOI: 10.1126/science.aao6266.
- Callaway, Ewan (7 June 2017). "Oldest Homo sapiens fossil claim rewrites our species' history". Nature. doi:10.1038/nature.2017.22114. Retrieved 11 June 2017.
- White, Tim D.; Asfaw, Berhane; Degusta, David; Gilbert, Henry; Richards, Gary D.; Suwa, Gen; Howell, Clark F. (June 2003). "Pleistocene Homo sapiens from Middle Awash, Ethiopia". Nature. 423 (6941): 742–7. Bibcode:2003Natur.423..742W. doi:10.1038/nature01669. PMID 12802332.
- Mayell, Hillary (16 February 2005). "Oldest Human Fossils Identified". National Geographic. Retrieved 1 October 2017.
- Bae, Christopher J.; Douka, Katerina; Petraglia, Michael D. (8 December 2017). "On the origin of modern humans: Asian perspectives". Science. 358 (6368): eaai9067. doi:10.1126/science.aai9067. Retrieved 10 December 2017.
- Kuo, Lily (10 December 2017). "Early humans migrated out of Africa much earlier than we thought". Quartz. Retrieved 10 December 2017.
- Zimmer, Carl (4 July 2017). "In Neanderthal DNA, Signs of a Mysterious Human Migration". New York Times. Retrieved 4 July 2017.
- Posth, Cosimo; et al. (4 July 2017). "Deeply divergent archaic mitochondrial genome provides lower time boundary for African gene flow into Neanderthals". Nature Communications. doi:10.1038/ncomms16046. Retrieved 4 July 2017.
- Green et al. (2010) suggest that their findings are consistent with Neanderthal admixture of up to 4% in some populations. 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; Maricic, T; Stenzel, U; Kircher, M; Patterson, N; Li, H; Zhai, W; Fritz, M. H. Y.; Hansen, N. F.; Durand, E. Y.; Malaspinas, A. S.; Jensen, J. D.; Marques-Bonet, T.; Alkan, C.; Prufer, K.; Meyer, M.; Burbano, H. A.; Good, J. M.; Schultz, R.; Aximu-Petri, A.; Butthof, A.; Hober, B.; Hoffner, B.; Siegemund, M.; Weihmann, A.; Nusbaum, C.; Lander, E. S.; Russ, C.; et al. (2010). "A Draft Sequence of the Neandertal Genome". Science. 328 (5979): 710–22. Bibcode:2010Sci...328..710G. doi:10.1126/science.1188021. PMC . PMID 20448178.. Eriksson and Manica (2012) proposed that the DNA overlap is a remnant of a common ancestor of both Neanderthals and modern humans. Anders Eriksson and Andrea Manica Effect of ancient population structure on the degree of polymorphism shared between modern human populations and ancient hominins PNAS 2012 : 1200567109v1-201200567. July 20, 2012
- Liu, Hua; et al. (2006). "A Geographically Explicit Genetic Model of Worldwide Human-Settlement History". The American Journal of Human Genetics. 79 (2): 230–237. doi:10.1086/505436. PMC . PMID 16826514.
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."Out of Africa Revisited". Science. 308 (5724): 921g. 2005-05-13. doi:10.1126/science.308.5724.921g. Retrieved 2009-11-23. Nature (2003-06-12). "Human evolution: Out of Ethiopia". Nature. 423 (6941): 692–695. Bibcode:2003Natur.423..692S. doi:10.1038/423692a. PMID 12802315. Retrieved 2009-11-23. "Origins of Modern Humans: Multiregional or Out of Africa?". ActionBioscience. Retrieved 2009-11-23. "Modern Humans – Single Origin (Out of Africa) vs Multiregional". Asa3.org. Retrieved 2009-11-23.
- Wolpoff, MH; Hawks, J; Caspari, R (2000). "Multiregional, not multiple origins". Am J Phys Anthropol. 112 (1): 129–36. doi:10.1002/(SICI)1096-8644(200005)112:1<129::AID-AJPA11>3.0.CO;2-K. PMID 10766948.
- Wolpoff, MH; JN Spuhler; FH Smith; J Radovcic; G Pope; DW Frayer; R Eckhardt; G Clark (1988). "Modern human origins". Science. 241 (4867): 772–4. Bibcode:1988Sci...241..772W. doi:10.1126/science.3136545. PMID 3136545.
- Human evolution: the fossil evidence in 3D, by Philip L. Walker and Edward H. Hagen, Dept. of Anthropology, University of California, Santa Barbara. Retrieved April 5, 2005.
- Green, R. E.; Krause, J; Ptak, S. E.; Briggs, A. W.; Ronan, M. T.; Simons, J. F.; et al. (2006). Analysis of one million base pairs of Neanderthal DNA. Nature. pp. 16, 330–336.
- Henn, Brenna; Gignoux, Christopher R.; Jobin, Matthew (2011). "Hunter-gatherer genomic diversity suggests a southern African origin for modern humans". Proceedings of the National Academy of Sciences of the United States of America. National Academy of Sciences. 108 (13): 5154–62. Bibcode:2011PNAS..108.5154H. doi:10.1073/pnas.1017511108. PMC . PMID 21383195.
- Wade, N (2006-03-07). "Still Evolving, Human Genes Tell New Story". The New York Times. Retrieved 2008-07-10.
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