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Homo () is a genus of great ape (family Hominidae) that emerged from the genus Australopithecus and encompasses a single extant species, Homo sapiens (modern humans), along with a number of extinct species (collectively called archaic humans) classified as either ancestral or closely related to modern humans; these include Homo erectus and Homo neanderthalensis. The oldest member of the genus is Homo habilis, with records of just over 2 million years ago. Homo, together with the genus Paranthropus, is probably most closely related to the species Australopithecus africanus within Australopithecus. The closest living relatives of Homo are of the genus Pan (chimpanzees and bonobos), with the ancestors of Pan and Homo estimated to have diverged around 5.7–11 million years ago during the Late Miocene.
H. erectus appeared about 2 million years ago and spread throughout Africa (debatably as another species called Homo ergaster) and Eurasia in several migrations. The species was adaptive and successful, and persisted for more than a million years before gradually diverging into new species around 500,000 years ago.
Anatomically modern humans ( H. sapiens) emerged close to 300,000 to 200,000 years ago in Africa, and H. neanderthalensis emerged around the same time in Europe and Western Asia. H. sapiens dispersed from Africa in several waves, from possibly as early as 250,000 years ago, and certainly by 130,000 years ago, with the so-called Southern Dispersal, beginning about 70,000–50,000 years ago,See:
leading to the lasting colonisation of Eurasia and Oceania by 50,000 years ago. H. sapiens met and interbred with archaic humans in Africa and in Eurasia.
This study raises the possibility of observed genetic affinities between archaic and modern human populations being mostly due to common ancestral polymorphisms. Separate archaic (non- sapiens) human species including Neanderthals are thought to have survived until around 40,000 years ago.
The genus Homo has not been strictly defined, even today. Since the early human fossil record began to slowly emerge from the earth, the boundaries and definitions of the genus have been poorly defined and constantly in flux. Because there was no reason to think it would ever have any additional members, Carl Linnaeus did not even bother to define Homo when he first created it for humans in the 18th century. The discovery of Neanderthal brought the first addition.
The genus Homo was given its taxonomic name to suggest that its member species can be classified as human. And, over the decades of the 20th century, fossil finds of pre-human and early human species from late Miocene and early Pliocene times produced a rich mix for debating classifications. There is continuing debate on delineating Homo from Australopithecus—or, indeed, delineating Homo from Pan. Even so, classifying the fossils of Homo coincides with evidence of: (1) competent human bipedalism in Homo habilis inherited from the earlier Australopithecus of more than four million years ago, as demonstrated by the Laetoli footprints; and (2) Oldowan having begun by 2.5 million years ago to 3 million years ago.
From the late-19th to mid-20th centuries, a number of new taxonomic names, including new generic names, were proposed for early human fossils; most have since been merged with Homo in recognition that Homo erectus was a single species with a large geographic spread of early migrations. Many such names are now regarded as "synonyms" with Homo, including Pithecanthropus,"ape-man", from Pithecanthropus erectus (Java Man), Eugène Dubois, Pithecanthropus erectus: eine menschenähnliche Übergangsform aus Java (1894), identified with the Pithecanthropus alalus (i.e. "non-speaking ape-man") hypothesized earlier by Ernst Haeckel Protanthropus, Sinanthropus,"Sinic man", from Sinanthropus pekinensis (Peking Man), Davidson Black (1927). Cyphanthropus,"crooked man", from Cyphanthropus rhodesiensis (Rhodesian Man) William Plane Pycraft (1928). Africanthropus,"African man", used by T.F. Dreyer (1935) for the Florisbad Skull he found in 1932 (also Homo florisbadensis or Homo helmei). Also the genus suggested for a number of archaic human skulls found at Lake Eyasi by Weinert (1938). Leaky, Journal of the East Africa Natural History Society (1942), p. 43. Telanthropus,"remote man"; from Telanthropus capensis (Broom and Robinson 1949), see (1961), p. 487. Atlanthropus,from Atlanthropus mauritanicus, name given to the species of fossils (three lower jaw bones and a parietal bone of a skull) discovered in 1954 to 1955 by Camille Arambourg in Tighennif, Algeria. and Tchadanthropus.
Classifying the genus Homo into species and subspecies is subject to incomplete information and remains poorly done. This has led to using common names ("Neanderthal" and "Denisovan"), even in scientific papers, to avoid trinomial names or the ambiguity of classifying groups as incertae sedis (uncertain placement)—for example, H. neanderthalensis vs. H. sapiens neanderthalensis, or H. georgicus vs. H. erectus georgicus. Some recently extinct species in the genus have been discovered only lately and do not as yet have consensus binomial names (see Denisova hominin). Since the beginning of the Holocene, it is likely that Homo sapiens (anatomically modern humans) has been the only extant species of Homo.
John Edward Gray (1825) was an early advocate of classifying taxa by designating tribes and families. Wood and Richmond (2000) proposed that Hominini ("hominins") be designated as a tribe that comprised all species of early humans and pre-humans ancestral to humans back to after the chimpanzee–human last common ancestor, and that Hominina be designated a subtribe of Hominini to include only the genus Homo — that is, not including the earlier upright walking hominins of the Pliocene such as Australopithecus, Orrorin tugenensis, Ardipithecus, or Sahelanthropus. Designations alternative to Hominina existed, or were offered: Australopithecinae (Gregory & Hellman 1939) and Preanthropinae (Cela-Conde & Altaba 2002); and later, Cela-Conde and Ayala (2003) proposed that the four genera Australopithecus, Ardipithecus, Praeanthropus, and Sahelanthropus be grouped with Homo within Hominini (sans Pan).
Especially since the 2010s, the delineation of Homo in Australopithecus has become more contentious. Traditionally, the advent of Homo has been taken to coincide with the first use of (the Oldowan industry), and thus by definition with the beginning of the Lower Palaeolithic. But in 2010, evidence was presented that seems to attribute the use of to Australopithecus afarensis around 3.3 million years ago, close to a million years before the first appearance of Homo. LD 350-1, a fossil mandible fragment dated to 2.8 Mya, discovered in 2013 in Afar Region, was described as combining "primitive traits seen in early Australopithecus with derived morphology observed in later Homo.See:
See also:
Some authors would push the development of Homo close to or even past 3 Mya. This finds support in a recent phylogenetic study in hominins that by using morphological, molecular and radiometric information, dates the emergence of Homo at 3.3 Ma (4.30 – 2.56 Ma). Others have voiced doubt as to whether Homo habilis should be included in Homo, proposing an origin of Homo with Homo erectus at roughly 1.9 Mya instead.
The most salient physiological development between the earlier australopithecine species and Homo is the increase in cranial capacity (ECV), from about in A. garhi to in H. habilis and further to in H. erectus, in H. heidelbergensis and up to in H. neanderthalensis. However, a steady rise in cranial capacity is observed already in Autralopithecina and does not terminate after the emergence of Homo, so that it does not serve as an objective criterion to define the emergence of the genus.
Weiss (1984) estimated that there have been about 44 billion members of the genus Homo from its origins to the evolution of H. erectus, about 56 billion individuals from H. erectus to the Neolithic, and another 51 billion individuals since the Neolithic. This provides the opportunity for an immense amount of new mutational variation to have arisen during human evolution.
A separate South African species Homo gautengensis has been postulated as contemporary with H. erectus in 2010.
Cladogram based on Dembo et al. (2016):
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Several of the Homo lineages appear to have surviving progeny through introgression into other lines. Genetic evidence indicates an archaic lineage separating from the other human lineages 1.5 million years ago, perhaps H. erectus, may have interbred into the Denisovans about 55,000 years ago.See:
Fossil evidence shows H. erectus s.s. survived at least until 117,000 yrs ago, and the even more basal H. floresiensis survived until 50,000 years ago. A 1.5-million-year H. erectus-like lineage appears to have made its way into modern humans through the Denisovans and specifically into the Papuans and aboriginal Australians. The genomes of non-sub-Saharan African humans show what appear to be numerous independent introgression events involving Neanderthal and in some cases also Denisovans around 45,000 years ago. The genetic structure of some sub-Saharan African groups seems to be indicative of introgression from a west Eurasian population some 3,000 years ago.
Some evidence suggests that Australopithecus sediba could be moved to the genus Homo, or placed in its own genus, due to its position with respect to e.g. H. habilis and H. floresiensis.
Homo erectus and related or derived archaic human species over the next 1.5 million years spread throughout Africa and Eurasia (see: Recent African origin of modern humans). Europe is reached by about 0.5 Mya by Homo heidelbergensis.
Homo neanderthalensis and H. sapiens develop after about 300 kya. Homo naledi is present in Southern Africa by 300 kya.
H. sapiens soon after its first emergence spread throughout Africa, and to Western Asia in several waves, possibly as early as 250 kya, and certainly by 130 kya. In July 2019, anthropologists reported the discovery of 210,000 year old remains of a H. sapiens and 170,000 year old remains of a H. neanderthalensis in Apidima Cave, Peloponnese, Greece, more than 150,000 years older than previous H. sapiens finds in Europe.
Most notable is the Southern Dispersal of H. sapiens around 60 kya, which led to the lasting peopling of Oceania and Eurasia by anatomically modern humans. H. sapiens interbred with archaic humans both in Africa and in Eurasia, in Eurasia notably with Neanderthals and .
Among extant populations of H. sapiens, the deepest temporal division is found in the San people of Southern Africa, estimated at close to 130,000 years, or possibly more than 300,000 years ago. Temporal division among non-Africans is of the order of 60,000 years in the case of Australo-Melanesians. Division of Europeans and East Asians is of the order of 50,000 years, with repeated and significant admixture events throughout Eurasia during the Holocene.
Archaic human species may have survived until the beginning of the Holocene, although they were mostly extinct or absorbed by the expanding H. sapiens populations by 40 kya (Neanderthal extinction).
There has historically been a trend to postulate new human species based on as little as an individual fossil. A "minimalist" approach to human taxonomy recognizes at most three species, H. habilis (2.1–1.5 Mya, membership in Homo questionable), H. erectus (1.8–0.1 Mya, including the majority of the age of the genus, and the majority of archaic varieties as subspecies,
| + Comparative table of Homo lineages | |||||||
| Homo habilis membership in Homo uncertain | 2,100–1,500 | Olduvai Gorge | 110–140 cm (3 ft 7 in – 4 ft 7 in) | 510–660 | Many | 1960 1964 | |
| Homo rudolfensis membership in Homo uncertain | 1,900 | Koobi Fora | 700 | 2 sites | 1972 1986 | ||
| H. gautengensis also classified as H. habilis | 1,900–600 | Sterkfontein | 100 cm (3 ft 3 in) | 3 individuals | 2010 2010 | ||
| Homo erectus | 1,900–140 | Homo ergaster, Eurasia | 180 cm (5 ft 11 in) | 850 (early) – 1,100 (late) | Many | 1891 1892 | |
| Homo ergaster African H. erectus | 1,800–1,300 | East and Southern Africa | 700–850 | Many | 1949 1975 | ||
| Homo antecessor | 1,200–800 | Western Europe | 175 cm (5 ft 9 in) | 1,000 | 2 sites | 1994 1997 | |
| H. floresiensis classification uncertain | 1,000–50 | Liang Bua | 100 cm (3 ft 3 in) | 400 | 7 individuals | 2003 2004 | |
| H. heidelbergensis early H. neanderthalensis | 600–300 | Europe, Africa | 180 cm (5 ft 11 in) | 1,100–1,400 | Many | 1907 1908 | |
| Homo cepranensis a single fossil, possibly H. heidelbergensis | c. 450 | Ceprano | 1,000 | 1 skull cap | 1994 2003 | ||
| Homo naledi | 335—236 | South Africa | 450 | 15 individuals | 2013 2015 | ||
| Homo longi | 309–138 | Northeast China | 1,420 | 1 individual | 1933 2021 | ||
| H. rhodesiensis early H. sapiens | c. 300 | Kabwe skull | 1,300 | Single or very few | 1921 1921 | ||
| Homo sapiens | c. 300–present | Worldwide | 150–190 cm (4 ft 11 in – 6 ft 3 in) | 950–1,800 | (extant) | —— 1758 | |
| Denisova hominin | c. 285 - c. 51 | Denisova Cave | 2 sites | 2000 2010 | |||
| Neanderthal | 240–40 | Europe, Western Asia | 170 cm (5 ft 7 in) | (heavily built) | 1,200–1,900 | Many | 1829 1864 |
| Nesher Ramla Homo classification uncertain | 140–120 | Israel | several individuals | 2021 | |||
| Penghu 1 possibly H. erectus or Denisova | c. 100 | Penghu | 1 individual | 2008(?) 2015 | |||
| Homo luzonensis | 134–49 | Philippines | 3 individuals | 2007 2019 |
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