Homo
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Homo (Template:Ety) is a genus of great ape (family Hominidae) that emerged from the early homininian genus Australopithecus, encompassing a single extant species, Homo sapiens (modern humans), along with a number of extinct species (e.g. Homo erectus and Homo neanderthalensis) classified as either ancestral or closely related to modern humans, collectively called archaic humans. Homo, together with the genus Paranthropus, is probably most closely related to the species Australopithecus africanus within Australopithecus.<ref name="Saylor 2015 483–488">Template:Cite journal</ref> The closest living relatives of Homo are of the hominin 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.<ref>Template:Cite journal</ref>
The oldest member of the genus is Homo habilis, with fossil records of just over 2 million years ago.Template:Efn 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.Template:Efn<ref name="Indriati-2011" />
Anatomically modern humans (early H. sapiens) emerged close to 300,000 to 200,000 years ago<ref name="NAT-20170607a">Template:Cite journal</ref> 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,<ref name="Posth">Template:Cite journal</ref><ref>See:
- Template:Cite journal
- Template:Cite journal</ref><ref name="HaberM">Template:Cite journal</ref> 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.<ref name="A draft sequence of the Neandertal">Template:Cite journal</ref><ref>Template:Cite journal
This study raises the possibility of observed genetic affinities between archaic and modern human populations being mostly due to common ancestral polymorphisms.</ref> Separate archaic (non-sapiens) human species including Neanderthals are thought to have survived until around 40,000 years ago.
Names and taxonomy
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The Latin noun Template:Lang (genitive Template:Lang) means "human being" or "man" in the generic sense of "human being, mankind".Template:Efn The binomial name Homo sapiens was coined by Carl Linnaeus (1758).Template:Efn<ref>Template:Cite book</ref> Names for other species of the genus were introduced from the second half of the 19th century (H. neanderthalensis 1864, H. erectus 1892).
The genus Homo has not been strictly defined, even today.<ref name="Schwartz 2015">Template:Cite journal</ref><ref name="Homo definition 2015">Template:Cite news</ref><ref>Template:Cite journal</ref> 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) human tool culture having begun by 2.5 million years ago to 3 million years ago.<ref>Template:Cite journal</ref>
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,<ref>"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</ref> Protanthropus,<ref>Template:Cite journal</ref> Sinanthropus,<ref>"Sinic man", from Sinanthropus pekinensis (Peking Man), Davidson Black (1927).</ref> Cyphanthropus,<ref>"crooked man", from Cyphanthropus rhodesiensis (Rhodesian Man) William Plane Pycraft (1928).</ref> Africanthropus,<ref>"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.</ref> Telanthropus,<ref>"remote man"; from Telanthropus capensis (Broom and Robinson 1949), see (1961), p. 487.</ref> Atlanthropus,<ref>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. Template:Cite journal</ref> and Tchadanthropus.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref>
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.<ref>Template:Cite thesis</ref> Some recently extinct species in the genus have been discovered only lately and do not as yet have consensus binomial names (see Denisova hominin).<ref name="Barras2012">Template:Cite web</ref> 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.<ref>Template:Cite journal</ref> 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.<ref>Template:Harvp</ref> Designations alternative to Hominina existed, or were offered: Australopithecinae (Gregory & Hellman 1939) and Preanthropinae (Cela-Conde & Altaba 2002);<ref>Template:Cite journal</ref><ref name="Cela-Conde-2003">Template:Cite journal</ref><ref>Template:Cite journal</ref> 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).<ref name="Cela-Conde-2003" />
Evolution
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Australopithecus and the appearance of Homo
Several species, including Australopithecus garhi, Australopithecus sediba, Australopithecus africanus, and Australopithecus afarensis, have been proposed as the ancestor or sister of the Homo lineage.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref> These species have morphological features that align them with Homo, but there is no consensus as to which gave rise to Homo.
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 stone tools (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 stone tools to Australopithecus afarensis around 3.3 million years ago, close to a million years before the first appearance of Homo.<ref name=Dikika>Template:Cite journal</ref> LD 350-1, a fossil mandible fragment dated to 2.8 Mya, discovered in 2013 in Afar, Ethiopia, was described as combining "primitive traits seen in early Australopithecus with derived morphology observed in later Homo.<ref>See:
See also:
- Template:Cite journal</ref> Some authors would push the development of Homo close to or even past 3 Mya.Template:Efn 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).<ref name="research.ed.ac.uk">Template:Cite journal</ref> 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.<ref>Template:Cite journal</ref>
The most salient physiological development between the earlier australopithecine species and Homo is the increase in endocranial volume (ECV), from about Template:Convert in A. garhi to Template:Convert in H. habilis and further to Template:Convert in H. erectus, Template:Convert in H. heidelbergensis and up to Template:Convert 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.<ref>Template:Cite journal</ref>
Homo habilis
Homo habilis emerged about 2.1 Mya. Already before 2010, there were suggestions that H. habilis should not be placed in the genus Homo but rather in Australopithecus.<ref>Template:Harvp</ref><ref name="Miller_2000">Template:Cite journal</ref> The main reason to include H. habilis in Homo, its undisputed tool use, has become obsolete with the discovery of Australopithecus tool use at least a million years before H. habilis.<ref name=Dikika/> Furthermore, H. habilis was long thought to be the ancestor of the more gracile Homo ergaster (Homo erectus). In 2007, it was discovered that H. habilis and H. erectus coexisted for a considerable time, suggesting that H. erectus is not immediately derived from H. habilis but instead from a common ancestor.<ref name="Spoor.et.al.2007" /> With the publication of Dmanisi skull 5 in 2013, it has become less certain that Asian H. erectus is a descendant of African H. ergaster which was in turn derived from H. habilis. Instead, H. ergaster and H. erectus appear to be variants of the same species, which may have originated in either Africa or Asia<ref>Template:Cite journal</ref> and widely dispersed throughout Eurasia (including Europe, Indonesia, China) by 0.5 Mya.<ref>Template:Cite book.</ref>
Homo erectus
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Homo erectus has often been assumed to have developed anagenetically from H. habilis from about 2 million years ago. This scenario was strengthened with the discovery of Homo erectus georgicus, early specimens of H. erectus found in the Caucasus, which seemed to exhibit transitional traits with H. habilis. For example they showed increased cranial capacity from around 575 cm3 in H. habilis to around 850 cm3 in H. erectus Template:Citation needed. As the earliest evidence for H. erectus was found outside of Africa, it was considered plausible that H. erectus developed in Eurasia and then migrated back to Africa. Based on fossils from the Koobi Fora Formation, east of Lake Turkana in Kenya, Spoor et al. (2007) argued that H. habilis may have survived beyond the emergence of H. erectus, so that the evolution of H. erectus would not have been anagenetically, and H. erectus would have existed alongside H. habilis for about half a million years (Template:Mya), during the early Calabrian.<ref name="Spoor.et.al.2007"> Template:Cite journal</ref> On 31 August 2023, researchers reported, based on genetic studies, that a human ancestor population bottleneck (from a possible 100,000 to 1000 individuals) occurred "around 930,000 and 813,000 years ago ... lasted for about 117,000 years and brought human ancestors close to extinction."<ref name="NYT-20230831">Template:Cite news</ref><ref name="SCI-20230831">Template:Cite journal</ref>
Weiss (1984) estimated that there have been about 44 billion (short scale) 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.<ref>Template:Cite journal</ref>
A separate South African species Homo gautengensis has been postulated as contemporary with H. erectus in 2010.<ref>Template:Cite journal</ref>
Phylogeny
Template:Human timeline A taxonomy of Homo within the great apes is assessed as follows, with Paranthropus and Homo emerging within Australopithecus (shown here cladistically granting Paranthropus, Kenyanthropus, and Homo).Template:EfnTemplate:Efn<ref name="Indriati-2011" /><ref name="Berger-2017" /><ref name="Schuster">Template:Cite journal</ref><ref name="Saylor 2015 483–488"/><ref name="Mondal-2019">Template:Cite journal</ref><ref name="Zeitoun 2003 148–156">Template:Cite journal</ref><ref name="Proceedings 2015">Template:Cite journal</ref><ref name="Dembo-2016">Template:Cite journal</ref><ref name="Ko-2016"/><ref>Template:Cite book</ref><ref>See:
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- Template:Cite journal</ref>Template:Excessive citations inline The exact phylogeny within Australopithecus is still highly controversial. Approximate radiation dates of daughter clades are shown in millions of years ago (Mya).<ref name="research.ed.ac.uk"/><ref name="Dembo-2016"/> Sahelanthropus and Orrorin, possibly sisters to Australopithecus, are not shown here. The naming of groupings is sometimes muddled as often certain groupings are presumed before any cladistic analysis is performed.<ref name="Zeitoun 2003 148–156"/>
Template:Clade Template:Clear Cladogram based on Dembo et al. (2016):<ref name="Dembo-2016" />Template:Clade
Cladogram based on Feng et al. (2024):<ref>Template:Cite journal</ref> Template:Clade
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.<ref>See:
- Template:Cite journal
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- Template:Cite journal</ref><ref name="Mondal-2019" /><ref name="Callaway 2016">Template:Cite journal</ref> 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.<ref name="Mondal-2019" /> 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.<ref>Template:Cite journal</ref><ref name="Callaway 2016" /> 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.<ref name="Ko-2016">Template:Cite journal</ref><ref>Template:Cite journal</ref>
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.<ref name="Proceedings 2015" /><ref>Template:Cite journal</ref>
Dispersal
By about 1.8 million years ago, H. erectus is present in both East Africa (H. ergaster) and in Western Asia (H. georgicus). The ancestors of Indonesian H. floresiensis may have left Africa even earlier.Template:Efn<ref name="Proceedings 2015" />
Homo erectus and related or derived archaic human species over the next 1.5 million years spread throughout Africa and Eurasia<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref> (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.<ref name="NYT-20190710">Template:Cite news</ref><ref name="PHYS-20190710">Template:Cite news</ref><ref name="NAT-20190710">Template:Cite journal</ref>
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.<ref name="A draft sequence of the Neandertal"/> H. sapiens interbred with archaic humans both in Africa and in Eurasia, in Eurasia notably with Neanderthals and Denisovans.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref>
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,<ref name="National Academy of Sciences">Template:Cite journal</ref> or possibly more than 300,000 years ago.<ref>Template:Cite journal</ref> 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).
List of lineages
Template:See also The species status of H. rudolfensis, H. ergaster, H. georgicus, H. antecessor, H. cepranensis, H. rhodesiensis, H. neanderthalensis, Denisova hominin, and H. floresiensis remain under debate. H. heidelbergensis and H. neanderthalensis are closely related to each other and have been considered to be subspecies of H. sapiens.
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,<ref>Template:Cite news</ref><ref> Template:Cite news</ref><ref> Template:Cite journal </ref> including H. heidelbergensis as a late or transitional variety<ref>Template:Cite web</ref><ref> Template:Cite journal</ref><ref> Template:Cite journal</ref>) and Homo sapiens (300 kya to present, including H. neanderthalensis and other varieties as subspecies). Consistent definitions and methodology of species delineation are not generally agreed upon in anthropology or paleontology. Indeed, speciating populations of mammals can typically interbreed for several million years after they begin to genetically diverge,<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref> so all contemporary "species" in the genus Homo would potentially have been able to interbreed at the time, and introgression from beyond the genus Homo can not a priori be ruled out.<ref>Template:Cite journal</ref> It has been suggested that H. naledi may have been a hybrid with a late surviving Australipith (taken to mean beyond Homo, ed.),<ref name="Berger-2017">Template:Cite journal</ref> despite the fact that these lineages generally are regarded as long extinct. As discussed above, many introgressions have occurred between lineages, with evidence of introgression after separation of 1.5 million years.
| Lineages | Temporal range (kya) |
Habitat | Adult height | Adult mass | Cranial capacity (cm3) |
Fossil record | Discovery/ publication of name |
|---|---|---|---|---|---|---|---|
| H. habilis membership in Homo uncertain |
2,100–1,500Template:EfnTemplate:Efn | Tanzania | 110–140 cm (3 ft 7 in – 4 ft 7 in) | Template:Convert | 510–660 | Many | 1960 1964 |
| H. rudolfensis membership in Homo uncertain |
1,900 | Kenya | 700 | 2 sites | 1972 1986 | ||
| H. gautengensis also classified as H. habilis |
1,900–600 | South Africa | 100 cm (3 ft 3 in) | 3 individuals<ref>Template:Cite journal</ref>Template:Efn | 2010 2010 | ||
| H. erectus | 2,000–140<ref>Template:Cite book</ref>Template:Efn<ref>Template:Cite journal</ref>Template:Efn | Africa, Eurasia | 180 cm (5 ft 11 in) | Template:Convert | 850 (early) – 1,100 (late) | ManyTemplate:EfnTemplate:Efn | 1891 1892 |
| H. ergaster African H. erectus |
1,800–1,300<ref name="Hazarika2007">Template:Cite book</ref> | East and Southern Africa | 700–850 | Many | 1949 1975 | ||
| H. antecessor | 1,200–800 | Western Europe | 175 cm (5 ft 9 in) | Template:Convert | 1,000 | 2 sites | 1994 1997 |
| H. floresiensis classification uncertain |
1,000–50 | Indonesia | 100 cm (3 ft 3 in) | Template:Convert | 400 | 7 individuals | 2003 2004 |
| H. heidelbergensis early H. neanderthalensis |
600–300Template:Efn | Europe, Africa | 180 cm (5 ft 11 in) | Template:Convert | 1,100–1,400 | Many | 1907 1908 |
| H. cepranensis a single fossil, possibly H. heidelbergensis |
c. 450<ref>Template:Cite journal</ref> | Italy | 1,000 | 1 skull cap | 1994 2003 | ||
| H. naledi | 335—236<ref name="eLIFE-2017a">Template:Cite journal</ref> | South Africa | Template:Height | Template:Convert | 450 | 15 individuals | 2013 2015 |
| H. longi | 309–138<ref>Template:Cite journal</ref> | Northeast China | 1,420<ref>Template:Cite journal</ref> | 1 individual | 1933 2021 | ||
| H. rhodesiensis early H. sapiens |
c. 300 | Zambia | 1,300 | Single or very few | 1921 1921 | ||
| H. sapiens Template:Small |
c. 300–presentTemplate:Efn | Worldwide | 150–190 cm (4 ft 11 in – 6 ft 3 in) | Template:Convert | 950–1,800 | (extant) | —— 1758 |
| Denisova hominin | c. 285 - c. 51 | Siberia | 2 sites | 2000 2010Template:Efn | |||
| H. neanderthalensis |
240–40<ref>Template:Cite journal</ref>Template:Efn | Europe, Western Asia | 170 cm (5 ft 7 in) | Template:Convert (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. 100Template:Efn | Taiwan | 1 individual | 2008(?) 2015 | |||
| H. luzonensis<ref name="NYT-20190410">Template:Cite news</ref> |
134–49<ref name="Détroit2019">Template:Cite journal</ref><ref name="Grün_2023">Template:Cite journal</ref> | Philippines | 3 individuals | 2007 2019 |
See also
Footnotes
References
Bibliography
External links
Template:Commons category Template:Wikispecies Template:Wikibooks
- Exploring the Hominid Fossil Record (Center for the Advanced Study of Hominid Paleobiology at George Washington University)
- Hominid species
- Prominent Hominid Fossils
- Mikko's Phylogeny archive
- Template:EOL
- Human Timeline (Interactive) – Smithsonian, National Museum of Natural History (August 2016).
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