Notable members ofHomo. Clockwise from top left: A reconstructedNeanderthal (Homo neanderthalensis) skeleton, amodern human (Homo sapiens) female with a child in India, a reconstructedHomo habilis skull, and a replica skull ofPeking Man (subspecies ofHomo erectus).
Homo (from Latinhomō'human') is agenus ofgreat ape (family Hominidae) that emerged from the genusAustralopithecus and encompasses only a single extant species,Homo sapiens (modern humans), along with a number ofextinct species (collectively calledarchaic humans) classified as eitherancestral or closely related to modern humans; these includeHomo erectus andHomo neanderthalensis. The oldest member of the genus isHomo habilis, with records of just over 2 million years ago.[a]Homo, together with the genusParanthropus, is probably most closely related to the speciesAustralopithecus africanus withinAustralopithecus.[4] The closest living relatives ofHomo are of the genusPan (chimpanzees andbonobos), with the ancestors ofPan andHomo estimated to have diverged around 5.7–11 million years ago during theLate Miocene.[5]
H. erectus appeared about 2 million years ago and spread throughoutAfrica (debatably as another species calledHomo ergaster) andEurasia inseveral 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.[b][6]
Anatomically modern humans (H. sapiens) emerged close to 300,000 to 200,000 years ago[7] in Africa, andH. neanderthalensis emerged around the same time inEurope andWestern Asia.H. sapiens dispersed from Africa inseveral waves, from possibly as early as 250,000 years ago, and certainly by 130,000 years ago, with the so-calledSouthern Dispersal, beginning about 70–50,000 years ago,[8][9][10] leading to thelasting colonisation of Eurasia andOceania by 50,000 years ago.H. sapiens met andinterbred with archaic humans in Africa and in Eurasia.[11][12] Separate archaic (non-sapiens) human species including Neanderthals are thought to have survived until around 40,000 years ago.
Evolutionary tree chart emphasizing the subfamily Homininae and the tribe Hominini. After diverging from the line toPonginae, the early Homininae split into the tribesHominini andGorillini. The early Hominini split further, separating the line toHomo from the lineage ofPan. Currently,tribe Hominini designates thesubtribesHominina, containing genusHomo;Panina, genusPan; andAustralopithecina, with several extinct genera—the subtribes are not labelled on this chart.
TheLatin nounhomō (genitivehominis) means "human being" or "man" in the generic sense of "human being, mankind".[c] Thebinomial nameHomo sapiens was coined byCarl Linnaeus (1758).[d][15] Names for other species of the genus were introduced from the second half of the 19th century (H. neanderthalensis 1864,H. erectus 1892).
The genusHomo has not been strictly defined, even today.[16][17][18] 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 defineHomo when he first created it for humans in the 18th century. The discovery of Neanderthal brought the first addition.
The genusHomo 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 lateMiocene and earlyPliocene times produced a rich mix for debating classifications. There is continuing debate on delineatingHomo fromAustralopithecus—or, indeed, delineatingHomo fromPan. Even so, classifying the fossils ofHomo coincides with evidence of: (1) competenthuman bipedalism inHomo habilis inherited from the earlierAustralopithecus of more than four million years ago, as demonstrated by theLaetoli footprints; and (2) human tool culture having begun by 2.5 million years ago to 3 million years ago.[19]
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 withHomo in recognition thatHomo erectus was a single species with a large geographic spread of early migrations. Many such names are now regarded as "synonyms" withHomo, includingPithecanthropus,[20]Protanthropus,[21]Sinanthropus,[22]Cyphanthropus,[23]Africanthropus,[24]Telanthropus,[25]Atlanthropus,[26] andTchadanthropus.[27][28]
Classifying the genusHomo 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 asincertae sedis (uncertain placement)—for example,H. neanderthalensis vs.H. sapiens neanderthalensis, orH. georgicus vs.H. erectus georgicus.[29] Some recently extinct species in the genus have been discovered only lately and do not as yet have consensus binomial names (seeDenisova hominin).[30] Since the beginning of theHolocene, it is likely thatHomo sapiens (anatomically modern humans) has been the only extant species ofHomo.
John Edward Gray (1825) was an early advocate of classifying taxa by designating tribes and families.[31] Wood and Richmond (2000) proposed thatHominini ("hominins") be designated as atribe that comprised all species of early humans and pre-humans ancestral to humans back toafter thechimpanzee–human last common ancestor, and that Hominina be designated asubtribe of Hominini to includeonly the genusHomo — that is,not including the earlier upright walking hominins of thePliocene such asAustralopithecus,Orrorin tugenensis,Ardipithecus, orSahelanthropus.[32] Designations alternative to Hominina existed, or were offered:Australopithecinae (Gregory & Hellman 1939) andPreanthropinae (Cela-Conde & Altaba 2002);[33][34][35] and later, Cela-Conde and Ayala (2003) proposed that the four generaAustralopithecus,Ardipithecus,Praeanthropus, andSahelanthropus be grouped withHomo withinHominini (sansPan).[34]
Especially since the 2010s, the delineation ofHomo inAustralopithecus has become more contentious. Traditionally, the advent ofHomo has been taken to coincide with the first use ofstone tools (theOldowan industry), and thus by definition with the beginning of theLower Palaeolithic. But in 2010, evidence was presented that seems to attribute the use ofstone tools toAustralopithecus afarensis around 3.3 million years ago, close to a million years before the first appearance ofHomo.[38]LD 350-1, a fossil mandible fragment dated to 2.8 Mya, discovered in 2013 inAfar, Ethiopia, was described as combining "primitive traits seen in earlyAustralopithecus with derived morphology observed in laterHomo.[39] Some authors would push the development ofHomo close to or even past 3 Mya.[e] This finds support in a recent phylogenetic study in hominins that by using morphological, molecular and radiometric information, dates the emergence ofHomo at 3.3 Ma (4.30 – 2.56 Ma).[40] Others have voiced doubt as to whetherHomo habilis should be included inHomo, proposing an origin ofHomo withHomo erectus at roughly 1.9 Mya instead.[41]
The most salient physiological development between the earlier australopithecine species andHomo is the increase inendocranial volume (ECV), from about 460 cm3 (28 cu in) inA. garhi to 660 cm3 (40 cu in) inH. habilis and further to 760 cm3 (46 cu in) inH. erectus, 1,250 cm3 (76 cu in) inH. heidelbergensis and up to 1,760 cm3 (107 cu in) inH. neanderthalensis. However, a steady rise in cranial capacity is observed already inAutralopithecina and does not terminate after the emergence ofHomo, so that it does not serve as an objective criterion to define the emergence of the genus.[42]
Homo habilis emerged about 2.1 Mya. Already before 2010, there were suggestions thatH. habilis should not be placed in the genusHomo but rather inAustralopithecus.[43][44] The main reason to includeH. habilis inHomo, its undisputed tool use, has become obsolete with the discovery ofAustralopithecus tool use at least a million years beforeH. habilis.[38] Furthermore,H. habilis was long thought to be the ancestor of the more gracileHomo ergaster (Homo erectus). In 2007, it was discovered thatH. habilis andH. erectus coexisted for a considerable time, suggesting thatH. erectus is not immediately derived fromH. habilis but instead from a common ancestor.[45] With the publication ofDmanisi skull 5 in 2013, it has become less certain that AsianH. erectus is a descendant of AfricanH. ergaster which was in turn derived fromH. habilis. Instead,H. ergaster andH. erectus appear to be variants of the same species, which may have originated in either Africa or Asia[46] and widely dispersed throughout Eurasia (includingEurope,Indonesia,China) by 0.5 Mya.[47]
Homo erectus has often been assumed to have developedanagenetically fromH. habilis from about 2 million years ago. This scenario was strengthened with the discovery ofHomo erectus georgicus, early specimens ofH. erectus found in theCaucasus, which seemed to exhibittransitional traits[example needed] withH. habilis. As the earliest evidence forH. erectus was found outside of Africa, it was considered plausible thatH. erectus developed in Eurasia and then migrated back to Africa. Based on fossils from theKoobi Fora Formation, east of Lake Turkana in Kenya, Spoor et al. (2007) argued thatH. habilis may have survived beyond the emergence ofH. erectus, so that the evolution ofH. erectus would not have been anagenetically, andH. erectus would have existed alongsideH. habilis for about half a million years (1.9 to 1.4 million years ago), during the earlyCalabrian.[45] On 31 August 2023, researchers reported, based on genetic studies, that ahuman ancestorpopulation 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."[48][49]
Weiss (1984) estimated that there have been about 44billion (short scale) members of the genusHomo from its origins to the evolution ofH. erectus, about 56 billion individuals fromH. erectus to theNeolithic, 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.[50]
A separate South African speciesHomo gautengensis has been postulated as contemporary withH. erectus in 2010.[51]
A taxonomy ofHomo within thegreat apes is assessed as follows, withParanthropus andHomo emerging withinAustralopithecus (shown herecladistically grantingParanthropus,Kenyanthropus, andHomo).[a][f][6][53][52][4][54][55][56][57][58][59][60][excessive citations] The exact phylogeny withinAustralopithecus is still highly controversial. Approximate radiation dates of daughter clades are shown in millions of years ago (Mya).[40][57]Sahelanthropus andOrrorin, possibly sisters toAustralopithecus, are not shown here. The naming of groupings is sometimes muddled as often certain groupings are presumed before any cladistic analysis is performed.[55]
Several of theHomo 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, perhapsH. erectus, may have interbred into the Denisovans about 55,000 years ago.[62][54][63] Fossil evidence showsH. erectus s.s. survived at least until 117,000 yrs ago, and the even more basalH. floresiensis survived until 50,000 years ago. A 1.5-million-yearH. erectus-like lineage appears to have made its way into modern humans through the Denisovans and specifically into the Papuans and aboriginal Australians.[54] 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.[64][63] 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.[58][65]
Some evidence suggests thatAustralopithecus sediba could be moved to the genusHomo, or placed in its own genus, due to its position with respect to e.g.H. habilis andH. floresiensis.[56][66]
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 IndonesianH. floresiensis may have left Africa even earlier.[g][56]
Homo neanderthalensis andH. 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 inseveral 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 aH. sapiens and 170,000 year old remains of aH. neanderthalensis inApidima Cave,Peloponnese,Greece, more than 150,000 years older than previousH. sapiens finds in Europe.[69][70][71]
Among extant populations ofH. sapiens, the deepest temporal division is found in theSan people of Southern Africa, estimated at close to 130,000 years,[74] or possibly more than 300,000 years ago.[75] Temporal division amongnon-Africans is of the order of 60,000 years in the case ofAustralo-Melanesians. Division ofEuropeans andEast Asians is of the order of 50,000 years, with repeated and significant admixture events throughout Eurasia during theHolocene.
Archaic human species may have survived until the beginning of theHolocene, although they were mostly extinct or absorbed by the expandingH. 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 inHomo questionable),H. erectus (1.8–0.1 Mya, including the majority of the age of the genus, and the majority of archaic varieties assubspecies,[76][77][78] includingH. heidelbergensis as a late or transitional variety[79][80][81]) andHomo sapiens (300 kya to present, includingH. neanderthalensis and other varieties assubspecies). 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,[82][83] so all contemporary "species" in the genusHomo would potentially have been able to interbreed at the time, and introgression from beyond the genusHomo can nota priori be ruled out.[84] It has been suggested thatH. naledi may have been a hybrid with a late survivingAustralipith (taken to mean beyondHomo, ed.),[53] 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.
^abThe conventional estimate on the age ofH. habilis is at roughly 2.1 to 2.3 million years.[1][2] Suggestions for pushing back the age to 2.8 Mya were made in 2015 based on the discovery ofa jawbone.[3]
^Homo erectus in the narrow sense (the Asian species) was extinct by 140,000 years ago;H. erectus soloensis, found inJava, is considered the latest known survival ofH. erectus. Formerly dated to as late as 50,000 to 40,000 years ago, a 2011 study pushed theH. e. soloensis extinction date back to 143,000 years ago at the latest, more likely before 550,000 years ago.[6]
^The word "human" itself is from Latinhumanus, an adjective formed on the root ofhomo, thought to derive from aProto-Indo-European word for "earth" reconstructed as*dhǵhem-.[13]
^In 1959,Carl Linnaeus was designated as thelectotype forHomo sapiens,[14] which means that following thenomenclatural rules,Homo sapiens was validly defined as the animal species to which Linnaeus belonged.
^Cela-Conde & Ayala (2003) recognize five genera within Hominina:Ardipithecus,Australopithecus (includingParanthropus),Homo (includingKenyanthropus),Praeanthropus (includingOrrorin), andSahelanthropus.[34]
^In a 2015 phylogenetic study,H. floresiensis was placed withAustralopithecus sediba,H. habilis andDmanisi Man, raising the possibility that the ancestors ofH. floresiensis left Africa before the appearance ofH. erectus, possibly even becoming the first hominins to do so and evolved further in Asia.[56]
^ConfirmedH. habilis fossils are dated to between 2.1 and 1.5 million years ago. This date range overlaps with the emergence ofHomo erectus.[85][86]
^Hominins with "proto-Homo" traits may have lived as early as 2.8 million years ago, as suggested by a fossil jawbone classified as transitional betweenAustralopithecus andHomo discovered in 2015.
^A species proposed in 2010 based on the fossil remains of three individuals dated between 1.9 and 0.6 million years ago. The same fossils were also classified asH. habilis,H. ergaster orAustralopithecus by other anthropologists.
^H. erectus may have appeared some 2 million years ago. Fossils dated to as much as 1.8 million years ago have been found both in Africa and in Southeast Asia, and the oldest fossils by a narrow margin (1.85 to 1.77 million years ago) were found in the Caucasus, so that it is unclear whetherH. erectus emerged in Africa and migrated to Eurasia, or if, conversely, it evolved in Eurasia and migrated back to Africa.
^Homo erectus soloensis, found inJava, is considered the latest known survival ofH. erectus. Formerly dated to as late as 50,000 to 40,000 years ago, a 2011 study pushed back the date of its extinction ofH. e. soloensis to 143,000 years ago at the latest, more likely before 550,000 years ago.[90]
^Now also included inH. erectus arePeking Man (formerlySinanthropus pekinensis) andJava Man (formerlyPithecanthropus erectus).
^The type fossil isMauer 1, dated to ca. 0.6 million years ago.The transition fromH. heidelbergensis toH. neanderthalensis between 300 and 243 thousand years ago is conventional, and makes use of the fact that there is no known fossil in this period. Examples ofH. heidelbergensis are fossils found atBilzingsleben (also classified asHomo erectus bilzingslebensis).
^The age ofH. sapiens has long been assumed to be close to 200,000 years, but since 2017 there have been a number of suggestions extending this time to as high as 300,000 years.In 2017, fossils found inJebel Irhoud (Morocco) suggest thatHomo sapiens may have speciated by as early as 315,000 years ago.[96]Genetic evidence has been adduced for an age of roughly 270,000 years.[97]
^The first humans with "proto-Neanderthal traits" lived in Eurasia as early as 0.6 to 0.35 million years ago (classified asH. heidelbergensis, also called achronospecies because it represents a chronological grouping rather than being based on clear morphological distinctions from eitherH. erectus orH. neanderthalensis). There is a fossil gap in Europe between300 and 243 kya, and by convention, fossils younger than 243 kya are called "Neanderthal".[99]
^younger than 450 kya, either between 190–130 or between 70–10 kya[100]
^Stringer, C.B. (1994). "Evolution of early humans". In Jones, S.; Martin, R.; Pilbeam, D. (eds.).The Cambridge Encyclopedia of Human Evolution. Cambridge:Cambridge University Press. p. 242.
^Schrenk, F.; Kullmer, O.; Bromage, T. (2007). "Chapter 9: The Earliest PutativeHomo Fossils". In Henke, W.; Tattersall, I. (eds.).Handbook of Paleoanthropology. pp. 1611–1631.doi:10.1007/978-3-540-33761-4_52.
^Lowery RK, Uribe G, Jimenez EB, Weiss MA, Herrera KJ, Regueiro M, Herrera RJ (November 2013). "Neanderthal and Denisova genetic affinities with contemporary humans: introgression versus common ancestral polymorphisms".Gene.530 (1):83–94.doi:10.1016/j.gene.2013.06.005.PMID23872234.This study raises the possibility of observed genetic affinities between archaic and modern human populations being mostly due to common ancestral polymorphisms.
^"African man", used by T.F. Dreyer (1935) for theFlorisbad Skull he found in 1932 (alsoHomo florisbadensis orHomo helmei). Also the genus suggested for a number of archaic human skulls found atLake Eyasi by Weinert (1938). Leaky,Journal of the East Africa Natural History Society (1942),p. 43.
^"remote man"; fromTelanthropus capensis (Broom and Robinson 1949), see (1961),p. 487.
^fromAtlanthropus mauritanicus,name given to the species of fossils (three lower jaw bones and a parietal bone of a skull) discovered in 1954 to 1955 byCamille Arambourg inTighennif, Algeria.Arambourg, C. (1955). "A recent discovery in human paleontology: Atlanthropus of ternifine (Algeria)".American Journal of Physical Anthropology.13 (2):191–201.doi:10.1002/ajpa.1330130203.
^Coppens, Y. (1965). "L'Hominien du Tchad".Actes V Congr. PPEC.I: 329f.
^Coppens, Y. (1966). "Le Tchadanthropus".Anthropologia.70:5–16.
^Gray, J.E. (1825). "An outline of an attempt at the disposition of Mammalia into Tribes and Families, with a list of genera apparently appertaining to each Tribe".Annals of Philosophy. new series:337–344.
^abMcPherron, S.P.; Alemseged, Z.; Marean, C.W.; Wynn, J.G.; Reed, D.; Geraads, D.; et al. (August 2010). "Evidence for stone-tool-assisted consumption of animal tissues before 3.39 million years ago at Dikika, Ethiopia".Nature.466 (7308):857–860.Bibcode:2010Natur.466..857M.doi:10.1038/nature09248.PMID20703305.S2CID4356816.The oldest direct evidence of stone tool manufacture comes fromGona (Ethiopia) and dates to between 2.6 and 2.5 million years (Myr) ago. [...] Here we report stone-tool-inflicted marks on bones found during recent survey work in Dikika, Ethiopia [... showing] unambiguous stone-tool cut marks for flesh removal [..., dated] to between 3.42 and 3.24 Myr ago [...] Our discovery extends by approximately 800,000 years the antiquity of stone tools and of stone-tool-assisted consumption of ungulates by hominins; furthermore, this behaviour can now be attributed to Australopithecus afarensis.
^Kimbel, W.H.; Villmoare, B. (July 2016)."From Australopithecus to Homo: the transition that wasn't".Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences.371 (1698): 20150248.doi:10.1098/rstb.2015.0248.PMC4920303.PMID27298460.A fresh look at brain size, hand morphology and earliest technology suggests that a number of keyHomo attributes may already be present in generalized species of Australopithecus, and that adaptive distinctions inHomo are simply amplifications or extensions of ancient hominin trends. [...] the adaptive shift represented by the ECV ofAustralopithecus is at least as significant as the one represented by the ECV of earlyHomo, and that a major 'grade-level' leap in brain size with the advent ofH. erectus is probably illusory.
^Wood & Richmond (2000), p. 41: "A recent reassessment of cladistic and functional evidence concluded that there are few, if any, grounds for retainingH. habilis inHomo, and recommended that the material be transferred (or, for some, returned) to Australopithecus (Wood & Collard, 1999)."
^abSpoor, F.;Leakey, M.G.; Gathogo, P.N.; Brown, F.H.; Antón, S.C.; McDougall, I.; et al. (August 2007). "Implications of new early Homo fossils from Ileret, east of Lake Turkana, Kenya".Nature.448 (7154):688–691.Bibcode:2007Natur.448..688S.doi:10.1038/nature05986.PMID17687323.S2CID35845.A partial maxilla assigned to H. habilis reliably demonstrates that this species survived until later than previously recognized, making an anagenetic relationship with H. erectus unlikely. The discovery of a particularly small calvaria of H. erectus indicates that this taxon overlapped in size with H. habilis, and may have shown marked sexual dimorphism. The new fossils confirm the distinctiveness of H. habilis and H. erectus, independently of overall cranial size, and suggest that these two early taxa were living broadly sympatrically in the same lake basin for almost half a million years.
^Curnoe, D. (June 2010). "A review of early Homo in southern Africa focusing on cranial, mandibular and dental remains, with the description of a new species (Homo gautengensis sp. nov.)".Homo.61 (3):151–77.doi:10.1016/j.jchb.2010.04.002.PMID20466364.
Mounier, A.; Caparros, M. (2015). "The phylogenetic status of Homo heidelbergensis – a cladistic study of Middle Pleistocene hominins".BMSAP (in French).27 (3–4):110–134.doi:10.1007/s13219-015-0127-4.ISSN0037-8984.S2CID17449909.
^Feng, X., Lu, D., Gao, F., Fang, Q., Feng, Y., Huang, X., Tan, C., Zhou, H., Li, Q., Zhang, C., Stringer, C., & Ni, X. (2024). The phylogenetic position of the Yunxian cranium elucidates the origin of Dragon Man and the Denisovans(p. 2024.05.16.594603). bioRxiv.https://doi.org/10.1101/2024.05.16.594603
^Curnoe, D. (June 2010). "A review of early Homo in southern Africa focusing on cranial, mandibular and dental remains, with the description of a new species (Homo gautengensis sp. nov.)".Homo.61 (3):151–177.doi:10.1016/j.jchb.2010.04.002.PMID20466364.
