Homo

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Homo
Temporal range: PlioceneHolocene, 2.4–0Ma
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Primates
Family: Hominidae
Tribe: Hominini
Subtribe: Hominina
Genus: Homo
Linnaeus, 1758
Type species
Homo sapiens
Linnaeus, 1758
Species

Homo sapiens
Homo gautengensis
Homo habilis
Homo erectus
Homo antecessor
Homo ergaster
Homo rhodesiensis
Homo heidelbergensis
Homo neanderthalensis
Homo floresiensis
Denisova hominin
Red Deer Cave people

Homo is the genus of hominids that includes modern humans and species closely related to them. The genus is estimated to be about 2.3 to 2.4 million years old,[1][2] possibly having evolved from australopithecine ancestors, with the appearance of Homo habilis. Several species, including Australopithecus garhi, Australopithecus sediba, Australopithecus africanus, and Australopithecus afarensis, have been proposed as the direct ancestor of the Homo lineage.[3][4] These species have morphological features that align them with Homo, but there is no consensus on which gave rise to Homo, assuming it was not an as-yet undiscovered species.

The most salient physiological development between the earlier australopith species and Homo is the increase in cranial capacity, from about 450 cm3 (27 cu in) in A. garhi to 600 cm3 (37 cu in) in H. habilis. Within the Homo genus, cranial capacity again doubled from H. habilis through Homo ergaster or H. erectus to Homo heidelbergensis by 0.6 million years ago. The cranial capacity of H. heidelbergensis overlaps with the range found in modern humans.

The advent of Homo was thought to coincide with the first evidence of stone tools (the Oldowan industry), and thus by definition with the beginning of the Lower Palaeolithic; however, recent evidence from Ethiopia now places the earliest evidence of stone tool usage at before 3.39 million years ago.[5] The emergence of Homo coincides roughly with the onset of Quaternary glaciation, the beginning of the current ice age.

Homo sapiens (modern humans) is the only surviving species in the genus, all others having become extinct. Homo neanderthalensis, traditionally considered the last surviving relative, died out about 24,000 years ago, though recent discoveries suggest that another species, Homo floresiensis, may have lived much more recently. The other extant Homininae—the chimpanzees and gorillas—have a limited geographic range. In contrast, the evolution of humans is a history of migrations and admixture. Humans repeatedly left Africa to populate Eurasia and finally the Americas, Oceania, and the rest of the world.

Naming[edit]

In biological sciences, particularly anthropology and palaeontology, the common name for all members of the genus Homo is "human".[citation needed]

The word homo is Latin meaning "human", and became to mean "man" in the gender-neutral sense in New Latin. The word "human" itself is from Latin humanus, an adjective cognate to homo, both thought to derive from a Proto-Indo-European word for "earth" reconstructed as *dhǵhem-.[6]

The binomial name Homo sapiens is due to Carl Linnaeus[7] (1758).[8]

Names for other species were coined beginning in the second half of the 19th century (H. neanderthalensis 1864, H. erectus 1892). A couple of recently discovered, recently extinct, species in the Homo Genus do not have accepted binomial names yet, Denisova hominin, and Red Deer Cave people. Classification of the Homo Genus into species and subspecies is poorly defined, highly disputed, and subject to political correctness and incomplete information, leading to difficulties in binomial naming, and the use of common names such as Neanderthal and Denisovan even in scientific papers.[9]

Species[edit]

Species status of Homo rudolfensis, Homo ergaster, H. georgicus, H. antecessor, H. cepranensis, H. rhodesiensis, Homo neanderthalensis, Denisova hominin, Red Deer Cave people and Homo floresiensis remains under debate. H. heidelbergensis and H. neanderthalensis are closely related to each other and have been considered to be subspecies of H. sapiens. Recently, nuclear DNA from a Neanderthal specimen from Vindija Cave has been sequenced, as well, using two different methods that yield similar results regarding Neanderthal and H. sapiens lineages, with both analyses suggesting a date for the split between 460,000 and 700,000 years ago, though a population split of around 370,000 years is inferred. The nuclear DNA results indicate about 30% of derived alleles in H. sapiens are also in the Neanderthal lineage. This high frequency may suggest some gene flow between ancestral humans and Neanderthal populations.[10]

Comparative table of Homo species
Species Lived when Ma Lived where Adult height Adult mass Cranial capacity (cm³) Fossil record Discovery / publication of name
Denisova hominin 0.04 Russia 1 site 2010
H. antecessor 1.2 – 0.8 Spain 175 cm (5 ft 9 in) 90 kg (200 lb) 1,000 2 sites 1997
H. cepranensis 0.9 – 0.35 Italy 1,000 1 skull cap 1994/2003
H. erectus 1.9 – 0.2 Africa, Eurasia (Java, China, India, Caucasus) 180 cm (5 ft 11 in) 60 kg (130 lb) 850 (early) – 1,100 (late) Many 1891/1892
H. ergaster 1.9 – 1.4 Eastern and Southern Africa 190 cm (6 ft 3 in) 700–850 Many 1975
H. floresiensis 0.10 – 0.012 Indonesia 100 cm (3 ft 3 in) 25 kg (55 lb) 400 7 individuals 2003/2004
H. gautengensis >2 – 0.6 South Africa 100 cm (3 ft 3 in) 1 individual 2010/2010
H. habilis 2.2 – 1.4 Africa 150 cm (4 ft 11 in) 33–55 kg (73–121 lb) 510–660 Many 1960/1964
H. heidelbergensis 0.6 – 0.35 Europe, Africa, China 180 cm (5 ft 11 in) 90 kg (200 lb) 1,100–1,400 Many 1908
H. neanderthalensis 0.35 – 0.03 Europe, Western Asia 170 cm (5 ft 7 in) 55–70 kg (121–154 lb) (heavily built) 1,200–1,900 Many (1829)/1864
H. rhodesiensis 0.3 – 0.12 Zambia 1,300 Very few 1921
H. rudolfensis 1.9 Kenya 700 2 sites 1972/1986
Red Deer Cave people 0.0145–0.0115 China Very few 2012
H. sapiens idaltu 0.16 – 0.15 Ethiopia 1,450 3 craniums 1997/2003
H. sapiens
(modern humans)
0.2 – present Worldwide 150 - 190 cm (4 ft 7 in - 6 ft 3 in) 50–100 kg (110–220 lb) 950–1,800 Still living —/1758

Migration and admixture[edit]

Map of the migration of modern humans out of Africa, based on mitochondrial DNA: Coloured rings indicate years before present, in thousands.

H. habilis, which is considered the first member of the genus Homo, might have given rise to H. ergaster (however questionable, as some finds suggest both species were contemporaneous).[11] Some of H. ergaster migrated to Asia, where they are named Homo erectus, and to Europe with Homo georgicus. H. ergaster in Africa and H. erectus in Eurasia evolved separately for almost two million years and presumably separated into two different species. Homo rhodesiensis, who were descended from H. ergaster, migrated from Africa to Europe and became Homo heidelbergensis and later (about 250,000 years ago) Homo neanderthalensis and the Denisova hominin in Asia. The first Homo sapiens, descendants of H. rhodesiensis, appeared in Africa about 250,000 years ago. About 100,000 years ago, some H. sapiens sapiens migrated from Africa to the Levant and met with resident Neanderthals, with some admixture.[12] Later, about 70,000 years ago, perhaps after the Toba catastrophe, a small group left the Levant to populate Eurasia, Australia and later the Americas. A subgroup among them met the Denisovans[13] and, after further admixture, migrated to populate Melanesia. In this scenario, non-African people living today are mostly of African origin ("Out of Africa model"). However, there was also some admixture with Neanderthals and Denisovans, who had evolved locally (the "multiregional hypothesis"). Recent genomic results from the group of Svante Pääbo also show that 30,000 years ago at least three major subspecies coexisted: Denisovans, Neanderthals and anatomically modern humans.[14] Today, only H. sapiens remains, with no other extant species.

See also[edit]

References[edit]

  1. ^ Stringer, C.B. (1994). "Evolution of early humans". In Steve Jones, Robert Martin & David Pilbeam (eds.). The Cambridge Encyclopedia of Human Evolution. Cambridge: Cambridge University Press. p. 242. ISBN 0-521-32370-3.  Also ISBN 0-521-46786-1 (paperback)
  2. ^ McHenry, H.M (2009). "Human Evolution". In Michael Ruse & Joseph Travis. Evolution: The First Four Billion Years. Cambridge, Massachusetts: The Belknap Press of Harvard University Press. p. 265. ISBN 978-0-674-03175-3. 
  3. ^ Pickering, R., Dirks, P. H., Jinnah, Z., De Ruiter, D. J., Churchill, S. E., Herries, A. I., ... & Berger, L. R. (2011). Australopithecus sediba at 1.977 Ma and implications for the origins of the genus Homo" Science 333(6048), 1421-1423.
  4. ^ Asfaw, B., White, T., Lovejoy, O., Latimer, B., Simpson, S., & Suwa, G. (1999). Australopithecus garhi: a new species of early hominid from Ethiopia" Science 284(5414), 629-635.
  5. ^ McPherron, S. P., Z. Alemseged, C. W. Marean, J. G. Wynn, D. Reed, D. Geraads, R. Bobe, and H. A. Bearat. 2010. Evidence for stone-tool-assisted consumption of animal tissues before 3.39 million years ago at Dikika, Ethiopia. Nature 466:857-860.
  6. ^ dhghem The American Heritage Dictionary of the English Language: Fourth Edition. 2000.
  7. ^ Note: In 1959, Linnaeus was designated as the lectotype for Homo sapiens (Stearn, W. T. 1959. "The background of Linnaeus's contributions to the nomenclature and methods of systematic biology", Systematic Zoology 8 (1): 4-22, p. 4) which means that following the nomenclatural rules, Homo sapiens was validly defined as the animal species to which Linnaeus belonged.
  8. ^ Linné, Carl von (1758). Systema naturæ. Regnum animale. (10 ed.). pp. 18, 20. Retrieved 19 November 2012. 
  9. ^ Alexandra Vivelo (2013), Characterization of Unique Features of the Denisovan Exome
  10. ^ Biological Anthropology: 2nd Edition. 2009. Craig Stanford et al.
  11. ^ Spoor F, Leakey M.G, Gathogo P.N, Brown F.H, Antón S.C, McDougall I, Kiarie C, Manthi F.K. & Leakey L.N. (2007), "Implications of new early Homo fossils from Ileret, east of Lake Turkana, Kenya", Nature 448(7154): p. 688-691.
  12. ^ Green RE, Krause J, et al. A draft sequence of the Neandertal genome. Science. 2010 May 7;328(5979):710-22. doi:10.1126/science.1188021 PMID 20448178
  13. ^ ^ Reich D, Green RE, Kircher M, et al. (December 2010). "Genetic history of an archaic hominin group from Denisova Cave in Siberia". Nature 468 (7327): 1053–60. doi:10.1038/nature09710. PMID 21179161.
  14. ^ Reich D ., et al. Denisova admixture and the first modern human dispersals into southeast Asia and Oceania. Am J Hum Genet. 2011 Oct 7;89(4):516-28, doi:10.1016/j.ajhg.2011.09.005 PMID 21944045.

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