preserved fossil

The best-preserved fossil is a maxilla which belonged to a 10-year-old individual found in Spain. Based on palaeomagnetic measurements, it is thought to be older than 780-857 ka (Falguères et al., 1999:351). The average brain was 1000 cm³ in volume. In 1994 and 1995, 80 fossils of six individuals that may have belonged to the species were found in Atapuerca, Spain. At the site were numerous examples of cuts where the flesh had been flensed from the bones, which indicates that H. antecessor could have practised cannibalism.

Homo antecessor was about 1.6-1.8 m (5½-6 feet) tall, and males weighed roughly 90 kg (200 pounds). Their brain sizes were roughly 1000–1150 cm³, smaller than the 1350 cm³ average of modern humans. Due to its scarcity, very little more is known about the physiology of H. antecessor, yet it was likely to have been more robust than H. heidelbergensis. According to Juan Luis Arsuaga, one of the co-directors of the excavation in Burgos, H. antecessor might have been right-handed, a trait that makes them different from the other apes. The hypothesis is based on tomography techniques. Arsuaga also claims that the frequency range of audition is similar to H. sapiens' which makes him believe that H. antecessor used a symbolic language and was able to reason. Arsuaga's team is currently pursuing a DNA map of H. antecessor after elucidating that of a bear that lived in northern Spain some 500,000 years ago.

Basing on teeth eruption pattern, the researchers think that Homo antecessor had the same development stages as Homo sapiens, though probably at a faster pace. Other features acquired by the species are a protruding occipital bun, a low forehead and a lack of a strong chin. Some of the remains are almost indistinguishable from the fossil attributable to KNM-WT 15000 (Turkana Boy) belonging to Homo ergaster

The only known fossils of H. antecessor are from two sites in the Sierra de Atapuerca region of northern Spain (Gran Dolina and Sima del Elefante).

Archaeologist Eudald Carbonell i Roura of the Universidad Rovira i Virgili in Tarragona, Spain and palaeoanthropologist Juan Luis Arsuaga Ferreras of the Complutense University of Madrid discovered Homo antecessor remains at the Gran Dolina site in the Sierra de Atapuerca, east of Burgos. The H. antecessor remains have been found in level 6 (TF6) of the Gran Dolina site. Over 80 bone fragments from six individuals were uncovered in 1994 and 1995. The site had also included roughly 200 stone tools and about 300 animal bones. Stone tools including a stone carved knife were found along with the ancient hominin remains. All these remains were dated at least 780,000 years old. The best-preserved remains are a maxilla (upper jawbone) and a frontal bone of an individual who died at 10–11 years old.

On 29 June 2007, Spanish researchers working at the Sima del Elefante site announced that they had recovered a molar dated to 1.1–1.2 million years ago. The molar was described as "well worn" and from an individual between 20 and 25 years of age. Additional findings announced on 27 March 2008 included the discovery of a mandible fragment, stone flakes, and evidence of animal bone processing.

Homo ergaster is an extinct chronospecies of Homo that lived in eastern and southern Africa from the end of the Pliocene epoch to the early Pleistocene, about 1.8-1.3 million years ago. There is still disagreement on the subject of the classification, ancestry, and progeny of H. ergaster, but it is now widely thought (though not agreed) to be the direct ancestor of later hominids such as Homo heidelbergensis, Homo sapiens and Homo neanderthalensis rather than Asian Homo erectus. It is one of the earliest members of the genus Homo, possibly descended from, or sharing a common ancestor with, Homo habilis.

The binominal name published in 1975 by Groves and Mazák is derived from the Greek εργαστηρ "workman", in reference to the comparatively advanced lithic technology developed by the species, introducing the Acheulean industry.

S.A paleontologist John Robinson first discovered a mandible of a new hominid in southern Africa in 1949; he named the species Telanthropus capensis, though it is now recognised as a member of Homo ergaster. The name was first applied by Colin Groves and Vratislav Mazák to KNM-ER 992, a mandible discovered near Lake Rudolf (now Lake Turkana), Kenya in 1975, which became the type-specimen of the species. The most complete skeleton of H. ergaster (and one of the most complete extinct hominids to date), KNM-WT 15000, was discovered at Lake Turkana, Kenya, in 1984 by paleoanthropologists Kamoya Kimeu and Alan Walker. They nicknamed the 1.6-million-year-old specimen "Turkana Boy".

Many paleoanthropologists still debate the definition of H. ergaster and H. erectus as separate species. Some call H. ergaster the direct African ancestor of H. erectus, proposing that H. ergaster emigrated out of Africa and into Asia, branching into a distinct species. Most dispense with the species-name ergaster, making no distinction between such fossils as the Turkana Boy and Peking Man. Though "Homo ergaster" has gained some acceptance as a valid taxon, H. ergaster and H. erectus are still usually defined as distinct African and Asian populations of the larger species H. erectus. (For the remainder of this article, the name "Homo ergaster"will be used to describe a distinct species for the convenience of continuity in reading.)

H. ergaster may be distinguished from H. erectus by its thinner skull-bones and lack of an obvious supraorbital sulcus. It may be distinguished from Homo heidelbergensis by its thinner bones, more protrusive face, and lower forehead. Derived features separating it from earlier species include reduced sexual dimorphism, a smaller, more orthognathous (less protrusive) face, a smaller dental arcade, and a larger cranial capacity (700-900cm³ in earlier ergaster-specimens, and 900-1100 in later specimens). It is estimated that H. ergaster stood at 1.9 metres (6.2 ft) tall. Remains have been found in Tanzania, Ethiopia, Kenya, and South Africa.

is generally accepted as the putative ancestor of the genus Homo, and often of H. ergaster most directly. This taxon's status as a legitimate species within "Homo", however, is particularly contentious. H. habilis and H. ergaster coexisted for 200,000-300,000 years, possibly indicating that these species diverged from a common ancestor. It is unclear the genetic influence that H. ergaster had on later hominids. Recent genetic analysis has generally supported the Out-of-Africa hypothesis, and this may designate H. ergaster the role of ancestor to all later hominids

H. ergaster diverged from the lineage of H. habilis between 1.9 and 1.8 million years ago; the lineage that emigrated Africa and fathered H. erectus diverged from the lineage of H. ergaster almost immediately after this. These early descendants of H. ergaster may have been discovered in Dmanisi, Georgia.H. ergaster remained stable for ca. 500,000 years in Africa before disappearing from the fossil record around 1.4 million years ago. No identifiable cause has been attributed to this disappearance; the later evolution of the similar H. heidelbergensis in Africa may indicate that this is simply a hole in the record, or that some intermediate species has not yet been discovered.

Homo ergaster used more diverse and sophisticated stone tools than its predecessors: H. erectus. H. ergaster refined the inherited Oldowan developing the first Acheulean bifacial axes: while the use of Acheulean tools began ca. 1.6 million years ago, the line of H. erectus diverged some 200,000 years before the general innovation of Acheulean technology. Thus the Asian migratory descendants of H. ergaster made no use of any Acheulean technology.

Sexual dimorphism in H. ergaster is greatly reduced from its australopithecine ancestors (around 20%), but still greater than dimorphism in modern humans. This diminished competition for mates between males, implied by the reduction in sexual dimorphism, may also correspond to the more modern social practices of ergaster. Not only was H. ergaster like modern humans in body, but also more in organisation and sociality than any earlier species. It is conceivable that H. ergaster was the first hominin to harness fire: whether as the containment of natural fire, or as the lighting of artificial fire, is still a matter of contention. It is now assumed, however, that erectus did have control of fire, as well as each other hominin sharing a common ancestor with ergaster. The social organisation of H. ergaster probably resembled that of modern hunter-gatherer societies. Unlike australopithecines, ergaster males presumably did not compete at all for females, which had themselves increased in size greatly in proportion to males. This reduced competition and dimorphism also coincided with an increase in brain size and efficiency of stone tools.

Homo ergaster was probably the first hominid to "use a human voice",clarification needed] though its symbolic cognition was probably somewhat more[clarification needed] limited. It was thought for a long time that H. ergaster was restricted in the physical ability to regulate breathing and produce complex sounds. This was based on Turkana Boy's cervical vertebrae, which were far narrower than in later humans. Discoveries of cervical vertebrae in Dmanisi, Georgia some .3 million years older than those of Turkana Boy are well within the normal human range. It has been established, furthermore, that the Turkana Boy probably suffered from a disease of the spinal column that resulted in narrower cervical vertebrae than in modern humans (as well as the older Dmanisi finds). While the Dmanisi finds have not been established definitively as H. ergaster; they are older than Turkana Boy (the only definite ergaster-vertebrae on record), and thereby suggest kinship to ergaster. Turkana Boy, therefore, may be an anomaly.

There is no archaeological evidence that Homo ergaster made use of symbolic thought (such as figurative art), but the well evolved brain and physical capabilities (along with reconfiguration of ergaster's breathing-apparatus) suggest some form of linguistic or symbolic communication.