Homo

chart emphasizing the subfamily Homininae and the tribe Hominini. After diverging from the line to Ponginae, the early Homininae split into the tribes Hominini and Gorillini. The early Hominini split further, separating the line to Homo from the lineage of Pan. Currently, tribe Hominini designates the subtribes Hominina, containing genus Homo; Panina, genus Pan; and Australopithecina, with several extinct genera—the subtribes are not labelled on this chart. The Latin noun (genitive ) means "human being" or "man" in the generic sense of "human being, mankind". The binomial name Homo sapiens was coined by Carl Linnaeus (1758). 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. 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 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. 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, Protanthropus, Sinanthropus, Cyphanthropus, Africanthropus, Telanthropus, Atlanthropus, 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). ==Evolution==

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. 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. 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. 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 Mya (4.30 – 2.56 Mya). 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 endocranial volume (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 Australopithecina 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. 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. 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. and widely dispersed throughout Eurasia (including Europe, Indonesia, China) by 0.5 Mya. Homo erectus may have evolved from H. ergaster'', possibly following an intense population bottleneck 800,000 to 900,000 years ago. 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 . 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 anagenetical, and H. erectus would have existed alongside H. habilis for about half a million years (), during the early Calabrian. 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." 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. A separate South African species Homo gautengensis has been postulated as contemporary with H. erectus in 2010. == Phylogeny ==

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). The exact phylogeny within Australopithecus is still highly controversial. Approximate radiation dates of daughter clades are shown in millions of years ago (Mya). Cladogram based on Feng et al. (2025): }} 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. 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. 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. 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. (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. 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). == List of lineages ==

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, including H. heidelbergensis as a late or transitional variety) 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, 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. It has been suggested that H. naledi may have been a hybrid with a late surviving Australipith (taken to mean beyond Homo, ed.), 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. == See also ==