Temporal range: Piacenzian-Present, 2.865–0 Ma
|Reconstruction of Homo erectus georgicus (Élisabeth Daynès, Musée de Préhistoire, Quinson, France)|
Homo is the genus that comprises the species Homo sapiens, which includes modern humans, as well as several extinct species classified as ancestral to or closely related to modern humans—as for examples Homo habilis and Homo neanderthalensis. The genus is about 2.8 million years old; it first appeared as its earliest species Homo habilis, which emerged from the genus Australopithecus, which itself had previously split from the lineage of Pan, the chimpanzees. Taxonomically, Homo is the only genus assigned to the subtribe Hominina which, with the subtribes Australopithecina and Panina, comprise the tribe Hominini (see evolutionary tree below). All species of the genus Homo plus those species of the australopithecines that arose after the split from Pan are called hominins.
Homo erectus appeared about two million years ago in East Africa (where it is dubbed Homo ergaster) and, in several early migrations, it spread throughout Africa and Eurasia. It was likely the first hominin to live in a hunter-gatherer society and to control fire. An adaptive and successful species, Homo erectus persisted for almost 2 million years before suddenly becoming extinct about 70,000 years ago (0.07 Ma)—perhaps a casualty of the Toba supereruption catastrophe.
Homo sapiens sapiens, or anatomically modern humans, emerged about 200,000 years ago (0.2 Ma) in East Africa (see Omo remains). There is division among scholars as to when H. s. sapiens became behaviorally modern; the debate is: modern behavior developed 1) simultaneously with anatomical development, or 2) separately, and was complete by 50,000 years ago (see Modern human behavior). Homo sapiens sapiens is the only surviving species and subspecies of the genus Homo; all others have become extinct.
Modern humans migrated from Africa as recently as 60,000 years ago, and during Upper Paleolithic times they spread throughout Africa, Eurasia, Oceania, and the Americas; and they encountered archaic humans en route of their migrations. Some archaic humans outside Africa survived alongside modern humans until about 40,000 years ago (see H. neanderthalensis), and possibly until as late as the times of the Epipaleolithic culture (about 12,000 years ago). DNA analysis provides some evidence of interbreeding between archaic and modern humans.
Names and taxanomy
- See Hominidae for an overview of taxonomy.
The Latin noun homō (genitive hominis) 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 beginning in the second half of the 19th century (H. neanderthalensis 1864, H. erectus 1892).
Even today, the genus Homo has not been properly defined. Since the early human fossil record began to slowly emerge from the earth, the boundaries and definitions of the genus Homo 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, as one body of scientists argue that the two species of chimpanzee should be classed with genus Homo rather than Pan. Even so, classifying the fossils of Homo coincides with evidences of: 1) competent human bipedalism in Homo habilis inherited from the earlier Australopithecus of more than four million years ago, (see Laetoli); and 2) human tool culture having begun by 2.5 million years ago.
From the late-19th to mid-20th century, 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 and singular species with a large geographic spread of early migrations. Many such names are now dubbed 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") in even 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 Homo are only recently discovered and do not as yet have consensus binomial names (see Denisova hominin and Red Deer Cave people).
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 Hominina.
Several species, including Australopithecus garhi, Australopithecus sediba, Australopithecus africanus, and Australopithecus afarensis, have been proposed as the direct ancestor 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. The advent of Homo was traditionally taken to coincide with the first use of stone tools (the Oldowan industry), and thus by definition with the beginning of the Lower Palaeolithic. The emergence of Homo also coincides roughly with the onset of Quaternary glaciation, the beginning of the current ice age.
A fossil jawbone dated to 2.8 million years ago which may represent an intermediate stage between Australopithecus and Homo was discovered in 2015 in Afar, Ethiopia. Some authors would push the development of Homo past 3 Mya, by including Kenyanthropus (a fossil dated 3.2 to 3.5 Mya, usually classified as an australopithecine species) into the genus Homo.
The most salient physiological development between the earlier australopithecine 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 genus Homo, 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.
Homo erectus has often been assumed to have developed anagenetically from Homo 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. 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 ( ), during the early Calabrian.
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. 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 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. Today, only H. sapiens remains, with no other extant species.
List of species
The species status of H. rudolfensis, H. ergaster, H. georgicus, H. antecessor, H. cepranensis, H. rhodesiensis, H. neanderthalensis, Denisova hominin, Red Deer Cave people, and H. 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 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 human and Neanderthal populations due to mating between the two.
Homo naledi was discovered near Johannesburg, South Africa in 2013 and announced on 10 September 2015. Fossils indicate the hominid was 1.45-1.5 meters tall and had a small brain. The fossils have yet to be dated.
|Species||Temporal range Mya||Habitat||Adult height||Adult mass||Cranial capacity (cm³)||Fossil record||Discovery / publication of name|
|H. habilis||2.1 – 1.5||Africa||110-140 cm (4 ft 11 in)||33–55 kg (73–121 lb)||510–660||Many||1960/1964|
|H. erectus||1.9 – 0.07||Africa, Eurasia (Java, China, India, Caucasus)||180 cm (5 ft 11 in)||60 kg (130 lb)||850 (early) – 1,100 (late)||Many||1891/1892|
membership in Homo uncertain
also classified as H. habilis
|1.9 – 0.6||South Africa||100 cm (3 ft 3 in)||3 individuals||2010/2010|
also classified as H. erectus
|1.8 – 1.3||Eastern and Southern Africa||700–850||Many||1975|
also classified as H. heidelbergensis
|1.2 – 0.8||Spain||175 cm (5 ft 9 in)||90 kg (200 lb)||1,000||2 sites||1997|
a single fossil, possibly H. erectus
|0.9 – 0.35||Italy||1,000||1 skull cap||1994/2003|
|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|
possibly a subspecies of H. sapiens
|0.35 – 0.04||Europe, Western Asia||170 cm (5 ft 7 in)||55–70 kg (121–154 lb) (heavily built)||1,200–1,900||Many||(1829)/1864|
||Undetermined||South Africa||150 centimetres (4 ft 11 in) tall||45 kilograms (99 lb)||450||15 individuals||2013/2015|
possibly H. erectus
|0.19 – 0.01||Taiwan||1 individual||pre-2008/2015|
also classified as H. heidelbergensis
|0.3 – 0.12||Zambia||1,300||Very few||1921|
|Worldwide||150 - 190 cm (4 ft 7 in - 6 ft 3 in)||50–100 kg (110–220 lb)||950–1,800||(extant)||—/1758|
|0.10 – 0.012||Indonesia||100 cm (3 ft 3 in)||25 kg (55 lb)||400||7 individuals||2003/2004|
possible H. sapiens subspecies or hybrid
|Red Deer Cave people
possible H. sapiens subspecies or hybrid
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- "Sinic man", from Sinanthropus pekinensis (Peking Man), Davidson Black (1927).
- "crooked man", from Cyphanthropus rhodesiensis (Rhodesian Man) William Plane Pycraft (1928).
- "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.
- "remote man"; from Telanthropus capensis (Broom and Robinson 1949), see (1961), p. 487.
- 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. 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.
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- "New discovery suggests Homo erectus originated from Asia". Daily News and Analysis. Mumbai, India: Diligent Media Corporation Ltd. Asian News International. June 8, 2011. Retrieved 2015-05-04.
- Frazier, Kendrick (November–December 2006). "Leakey Fights Church Campaign to Downgrade Kenya Museum's Human Fossils". Skeptical Inquirer. Amherst, NY: Committee for Skeptical Inquiry. 30 (6). ISSN 0194-6730. Retrieved 2015-05-04.
- Now also included in H. erectus are Peking Man (formerly Sinanthropus pekinensis) and Java Man (formerly Pithecanthropus erectus). H. erectus is now grouped into various subspecies, including Homo erectus erectus, Homo erectus yuanmouensis, Homo erectus lantianensis, Homo erectus nankinensis, Homo erectus pekinensis, Homo erectus palaeojavanicus, Homo erectus soloensis, Homo erectus tautavelensis, Homo erectus georgicus. The distinction from descendant species such as Homo ergaster, Homo floresiensis, Homo antecessor, Homo heidelbergensis and indeed Homo sapiens is not entirely clear.
- Curnoe, Darren (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 - Journal of Comparative Human Biology. Amsterdam, the Netherlands: Elsevier. 61 (3): 151–177. doi:10.1016/j.jchb.2010.04.002. ISSN 0018-442X. PMID 20466364. 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 as H. habilis, H. ergaster or Australopithecus by other anthropologists.
- Hazarika, Manjil (2007). "Homo erectus/ergaster and Out of Africa: Recent Developments in Paleoanthropology and Prehistoric Archaeology" (PDF). EAA Summer School eBook. 1. European Anthropological Association. pp. 35–41. Retrieved 2015-05-04. "Intensive Course in Biological Anthrpology, 1st Summer School of the European Anthropological Association, 16–30 June, 2007, Prague, Czech Republic"
- The type fossil is Mauer 1, dated to ca. 0.6 million years ago. The transition from H. heidelbergensis to H. neanderthalensis at about 0.35 to 0.25 million years ago is largely conventional. Relevant examples are fossils found at Bilzingsleben (also classified as Homo erectus bilzingslebensis).
- Bischoff, James L.; Shamp, Donald D.; Aramburu, Arantza; et al. (March 2003). "The Sima de los Huesos Hominids Date to Beyond U/Th Equilibrium (>350 kyr) and Perhaps to 400–500 kyr: New Radiometric Dates". Journal of Archaeological Science. Amsterdam, the Netherlands: Elsevier. 30 (3): 275–280. doi:10.1006/jasc.2002.0834. ISSN 0305-4403. The first humans with "proto-Neanderthal traits" lived in Eurasia as early as 0.6 to 0.35 million years ago (classified as H. heidelbergensis, also called a chronospecies because it represents a chronological grouping rather than being based on clear morphological distinctions from either H. erectus or H. neanderthalensis), with the first "true Neanderthals" appearing between 0.25 and 0.2 million years ago.
- Chang, Chun-Hsiang; Kaifu, Yousuke; Takai, Masanaru; Kono, Reiko T.; Grün, Rainer; Matsu’ura, Shuji; Kinsley, Les; Lin, Liang-Kong (2015). "The first archaic Homo from Taiwan". Nature Communications. 6: 6037. doi:10.1038/ncomms7037.
- "Fossil Reanalysis Pushes Back Origin of Homo sapiens". Scientific American. Stuttgart: Georg von Holtzbrinck Publishing Group. February 17, 2005. ISSN 0036-8733. Retrieved 2015-05-04. The oldest fossil remains of anatomically modern humans are the Omo remains, which date to 195,000 (±5,000) years ago and include two partial skulls as well as arm, leg, foot and pelvis bones.
- McDougall, Ian; Brown, Francis H.; Fleagle, John G. (February 17, 2005). "Stratigraphic placement and age of modern humans from Kibish, Ethiopia". Nature. London: Nature Publishing Group. 433 (7027): 733–736. Bibcode:2005Natur.433..733M. doi:10.1038/nature03258. ISSN 0028-0836. PMID 15716951. H. sapiens idaltu is a confirmed subspecies, based on 3 craniums dated 0.16 – 0.15 Mya found in Ethiopia (1997/2003).
- Serre; Langaney, André; Chech, Mario; Teschler-Nicola, Maria; Paunovic, Maja; Mennecier, Philippe; Hofreiter, Michael; Possnert, Göran; Pääbo, Svante; et al. (2004). "No evidence of Neandertal mtDNA contribution to early modern humans". PLoS Biology. 2 (3): 313–7. doi:10.1371/journal.pbio.0020057. PMC . PMID 15024415.
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- 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
- Homo at the Encyclopedia of Life
- Human Timeline (Interactive) – Smithsonian, National Museum of Natural History (August 2016).