Homo sapiens

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This article is about Homo sapiens as a taxonomic classification. For a more general perspective on the human species, see Human. For other uses, see Homo sapiens (disambiguation).
Homo sapiens
Temporal range: 0.195–0 Ma
Middle Pleistocene – Recent
man and woman in northern Thailand – husband carries stem of banana-plant, which will be fed to their pigs
Male and female Homo sapiens sapiens from hilltribe in Thailand
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Primates
Suborder: Haplorhini
Family: Hominidae
Genus: Homo
Species: H. sapiens
Binomial name
Homo sapiens
Linnaeus, 1758
Subspecies

Homo sapiens idaltu
Homo sapiens sapiens
Homo neanderthalensis?
Homo rhodesiensis?

Homo sapiens (Latin: "man who knows") is the binomial nomenclature (also known as the scientific name) for the human species. Homo is the human genus, which also includes Neanderthals and many other extinct species of hominid; H. sapiens is the only surviving species of the genus Homo. Modern humans are the subspecies Homo sapiens sapiens, which differentiates them from what has been argued to be their direct ancestor, Homo sapiens idaltu. The ingenuity and adaptability of Homo sapiens has led to its becoming, arguably, the most influential species on the planet; it is currently deemed of least concern on the Red List of endangered species by the International Union for the Conservation of Nature.[1]

Name and taxonomy[edit]

Further information: Homo and Names for the human species

The binomial name Homo sapiens was coined by Carl Linnaeus (1758).[2] The Latin noun homō (genitive hominis) means "man, human being".

Subspecies of H. sapiens include Homo sapiens idaltu and the only extant subspecies, Homo sapiens sapiens. Some sources show Neanderthals (Homo neanderthalensis) as a subspecies (Homo sapiens neanderthalensis).[3][4] Similarly, the discovered specimens of the Homo rhodesiensis species have been classified by some as a subspecies (Homo sapiens rhodesiensis), but these last two subspecies classifications are not widely accepted by scientists.

Origin[edit]

Schematic representation of the emergence of H. sapiens from earlier species of Homo. The horizontal axis represents geographic location; the vertical axis represents time in millions of years ago. Blue areas denote the presence of a certain species at a given time and place. Early modern humans spread from Africa across different regions of the globe and interbred with other descendants of Homo heidelbergensis, namely Neanderthals, Denisovans, and unknown archaic African hominins (top right).[5]

Traditionally, there are two competing views in paleoanthropology about the origin of H. sapiens: the recent African origin and the multiregional origin.

Since 2010, genetic research has led to the emergence of an intermediate position, characterised by mostly recent African origin plus limited admixture with archaic humans.

The recent African origin of modern humans is the mainstream model that describes the origin and early dispersal of anatomically modern humans. 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. According to genetic and fossil evidence, archaic Homo sapiens evolved to anatomically modern humans solely in Africa, between 200,000 and 100,000 years ago, with members of one branch leaving Africa by 60,000 years ago and over time replacing earlier human populations such as Neanderthals and Homo erectus.

The recent single origin of modern humans in East Africa is the near-consensus position held within the scientific community.[6][7][8][9][10] However, recent sequencing of the full Neanderthal Genome suggests Neanderthals and some modern humans share some ancient genetic lineages. The authors of the study 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.[11] In August 2012, a study by scientists at the University of Cambridge has questioned this conclusion, hypothesising instead that the DNA overlap is a remnant of a common ancestor of both Neanderthals and modern humans.[12][13]

The multiregional origin model provides an explanation for the pattern of human evolution proposed by Milford H. Wolpoff[14] in 1988.[15] 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, evolving worldwide to modern Homo sapiens sapiens.

Evolution[edit]

The time frame for the evolution of the genus Homo out of the chimpanzee–human last common ancestor is roughly 10 to 2 million years ago, that of H. sapiens out of Homo erectus roughly 1.8 to 0.2 million years ago.

Scientific study of human evolution is concerned, primarily, with the development of the genus Homo, but usually involves studying other hominids and hominines as well, such as Australopithecus. "Modern humans" are defined as the Homo sapiens species, of which the only extant subspecies is known as Homo sapiens sapiens.

Homo sapiens idaltu, the other known subspecies, is now extinct.[16] 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.[17]

Similarly, the discovered specimens of the Homo rhodesiensis species have been classified by some as a subspecies, but this classification is not widely accepted.

Anatomically modern humans first appear in the fossil record in Africa about 195,000 years ago (see Omo remains), and studies of molecular biology give evidence that the approximate time of divergence from the common ancestor of all modern human populations was 200,000 years ago.[18][19][20][21][22] The broad study of African genetic diversity found the ǂKhomani San people to express the greatest genetic diversity among the 113 distinct populations sampled, making them one of 14 "ancestral population clusters". The research also located the origin of modern human migration in south-western Africa, near the coastal border of Namibia and Angola.[23][24]

The forces of natural selection have continued to operate on human populations, with evidence that certain regions of the genome display directional selection in the past 15,000 years.[25]

References[edit]

  1. ^ a b Global Mammal Assessment Team (2008). Homo sapiens. In: IUCN 2008. IUCN Red List of Threatened Species. Retrieved 12 February 2015.
  2. ^ Linné, Carl von (1758). Systema naturæ. Regnum animale. (10 ed.). pp. 18, 20. Retrieved 19 November 2012. .
  3. ^ 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 2752594. PMID 19805257. 
  4. ^ Harvati, K.; Frost, S.R.; McNulty, K.P. (2004). "Neanderthal taxonomy reconsidered: implications of 3D primate models of intra- and interspecific differences". PMID 14745010. Retrieved 2015-02-06. 
  5. ^ Stringer, C. (2012). "What makes a modern human". Nature 485 (7396): 33–35. doi:10.1038/485033a. PMID 22552077. 
  6. ^ Hua Liu, et al. A Geographically Explicit Genetic Model of Worldwide Human-Settlement History. The 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.
  7. ^ "Out of Africa Revisited - 308 (5724): 921g - Science". Sciencemag.org. 2005-05-13. doi:10.1126/science.308.5724.921g. Retrieved 2009-11-23. 
  8. ^ Nature (2003-06-12). "Access : Human evolution: Out of Ethiopia". Nature. Retrieved 2009-11-23. 
  9. ^ "Origins of Modern Humans: Multiregional or Out of Africa?". ActionBioscience. Retrieved 2009-11-23. 
  10. ^ "Modern Humans - Single Origin (Out of Africa) vs Multiregional". Asa3.org. Retrieved 2009-11-23. 
  11. ^ Green, RE; Krause, J; Briggs, AW; Maricic, T; Stenzel, U; Kircher, M; Patterson, N; Li, H et al. (2010). "A Draft Sequence of the Neandertal Genome". Science (Science (journal)) 328 (5979): 710–22. doi:10.1126/science.1188021. PMID 20448178. 
  12. ^ Study casts doubt on human-Neanderthal interbreeding theory, The Guardian, Tuesday 14 August 2012
  13. ^ 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
  14. ^ 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. 
  15. ^ 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. doi:10.1126/science.3136545. PMID 3136545. 
  16. ^ 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.
  17. ^ 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. 
  18. ^ nsf.gov - National Science Foundation (NSF) News - New Clues Add 40,000 Years to Age of Human Species - US National Science Foundation (NSF)
  19. ^ "Age of ancient humans reassessed". BBC News. February 16, 2005. Retrieved April 10, 2010. 
  20. ^ The Oldest Homo Sapiens: – URL retrieved May 15, 2009
  21. ^ 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. 
  22. ^ 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. 
  23. ^ 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. doi:10.1073/pnas.1017511108. 
  24. ^ Gill, Victoria (May 1, 2009). "Africa's genetic secrets unlocked". BBC News. ; the results were published in the online edition of the journal Science.
  25. ^ Wade, N (2006-03-07). "Still Evolving, Human Genes Tell New Story". The New York Times. Retrieved 2008-07-10.