Homo habilis
The fossil OH7 ( replica ) the holotype of Homo habilis
Homo habilis is an extinct species of the genus Homo. All previously known as Homo habilis finds come from East African rock strata.
Naming
The name of the genus Homo is derived from the Latin homo [ hɔmo ː ] "man." The epithet habilis also comes from Latin and means " sent", "capable", " gifted "; it was commended to the authors of the first description by Raymond Dart. Homo habilis therefore means " skillful man ".
Age
All known finds of Homo habilis were dated to an age of from about 2.1 to 1.5 million years .. From when to when there was a fossil species, but can only be approximated in most cases. For one, the fossil record is patchy: there are usually very few copies for a fossil Article On the other hand, the dating methods, although a certain age from, but this with a significant inaccuracy; this inaccuracy then forms the outer limits in the "from ... to " information for lifetimes. All published age data are therefore preliminary datings, which also claimed the discovery of more copies may need to be revised.
Why the species is extinct, is not known.
First description
In June 1959 discovered Heselon Mukiri, a longtime employee of Louis Leakey, in Olduvai Gorge in northern Tanzania a small mandibular fragment with a wisdom tooth ( molar M3; Archive number OH 4 = Olduvai hominid 4) and the remains of two other teeth. In the fall of 1960, Jonathan Leakey came there on the approximately 1.75 million years old, complete and toothed lower jaw of a child (OH 7), in which the wisdom teeth had not yet erupted. After another bone finds published Louis Leakey, Phillip Tobias and John Napier in 1964 in the journal Nature, the first description of the new species Homo habilis, which OH 7 (called " Johnny's child " ) declared the type specimen and the fossils OH 8 and OH 4 as well as other findings as paratypes were reported. Under the archive number OH 7 of juvenile lower jaw and an upper jaw tooth of the associated skull and 13 bones of a young hand had been summarized; with OH 8 is a group of related hand and foot bones from a presumably also not yet adult individual.
In order to assign the species of the genus Homo newly described, the definition of this genus has been revised in the original description of Homo habilis. It had been customary until then to define the boundary between Australopithecus and Homo on the basis of brain volume, a portion of the research 700 cc, other 750 cc or 800 cc and - most influential - Ernst Mayr in 1950 even 900 cc as " had reported cerebral Rubicon "; in the original description of H. habilis this lower limit brain volume for species was, however, the genus Homo reduced to 600 cc.
Only since the 1980s, the species is generally recognized in the art as their own.
Further finds
In addition to the findings from the Olduvai Gorge in Tanzania several fossils from the eastern edge of Lake Turkana (Kenya ) Homo habilis were attributed, among other things, in 1975 discovered partially preserved skeleton KNM- ER 3735 from Koobi Fora in the northeast of Lake Turkana and the maxillary AL 666-1 from Hadar in Ethiopia, also South African remains from Sterkfontein ( Stw 53 skull ) and Swartkrans ( the skull fragment SK 847).
The associated finds (including prehistoric relatives of horses, tapirs, and pigs and hippos and river otter ) suggest a habitat that consisted of grassy savannas, streams and lakes with riparian woodland ( gallery forests ). In the fossil -bearing strata stone tools from the Oldowan type, and animal bones were found with notches, which can be interpreted as cut marks; it was concluded that Homo habilis meat has separated and eaten from the bones.
From the period of two million years ago, the fossils of Homo rudolfensis come. However, no associated finds of bones were discovered in the area of his head and his arms and legs so that the physique of Homo rudolfensis is unsecured below the head. However, the skull of Homo rudolfensis was discovered a wealth of individual limb bones as well as a basin in the Fund layers, which significantly differ from Homo habilis and probably belong to Homo rudolfensis.
Features
Compared to earlier Australopithecus and Paranthropus had to simultaneously living Homo habilis with about 650 cc of a 30% larger brain volume (compared to Homo sapiens from 1200 to 1400 cc ).
Because except in connection with the mandible OH 7 first no body bones were found and the definition of the type in the original description was based mainly on the construction of the teeth and jaw, a secure reconstruction of the anatomical conditions below the head is so far from: In the same Fund layers were in fact recovered fossils, which are attributed to Paranthropus boisei. Therefore, the assignment of the bones of limbs, trunk and has not yet been secured to one or the other type.
Nevertheless, two were designated as OH 35, isolated leg bones found in 1982 - and again in 2008 - Homo habilis attributed and " habitual bipedalism " derived from their shape. The body size of a female Homo habilis was estimated to be about one meter, body weight 25 to 35 kg. Leakey et al. designated in the original description at the same time as a further criterion of membership of Homo habilis to Homo an opposable thumb and related areas of the precision grip. Both statements are, however, doubted today: It is possible that Homo habilis was moving only temporarily maintained continuously, and also claimed the precision grip was questioned.
The OH 7 with associated hand points - as in modern humans - a relatively large thumbs and broad fingertips, the arms are longer than the legs. However, the finger - as in chimpanzees - relatively long and curved, indicating a frequent stay on trees. An analysis of the humerus of OH 62 showed that it has significant chimpanzee -like features and is significantly different from the characteristics of Homo erectus, . Since other finds from the same layers of Olduvai Gorge ( Tanzania) and from Lake Turkana (Kenya ) have some chimpanzees, some human-like characteristics, but their allocation to Homo habilis or Paranthropus boisei is not secure, is also still unclear, if the physique of Homo habilis had mixed characteristics or whether all human-like fossils are to provide to Homo, the chimpanzee-like, however, to Paranthropus.
Controversies
The classification of known as Homo habilis finds in the family tree of the Hominini is controversial since the first description of this type in April 1964. In May 1964, the first reservations were published, and a few weeks later wrote the influential British anatomist and paleoanthropologist Wilfrid Le Gros Clark, he hoped that Homo habilis just as quickly disappear again, as he had come. Critics of naming the fossils were asked to Australopithecus, which is why at times the name " Australopithecus habilis " ( " skillful southern ape " ) was used in parts of the literature. For example, Bernard Wood wrote in Science in 1999 that " the earliest taxon that meets the criteria [ for the genus Homo ], Homo ergaster or early African Homo erectus " was; 2011 Wood renewed his criticism.
But was accepted by both sides that the habilis fossils included a temporal and anatomical gap between the previously known Australopithecus variants and those of Homo erectus. The finds were often even interpreted to the effect that Homo habilis was a direct ancestor of Homo erectus. Even the discovery of OH 62 in 1986 as well as newer discoveries were introduced to this by Louis Leakey and previously commonly held hypothesis, however, raise doubts. 2007 was published by a group led by Meave Leakey and Louise Leakey, a discovery that Homo habilis is assigned and has been dated to an age of 1.44 million years. That would mean that Homo habilis and Homo erectus / Homo ergaster existed up to a half a million years side by side. Scientists suggest that both species had occupied different ecological niches and so were not direct competitors.
Maybe now experienced the earlier occasion of researchers held view, Homo habilis was assigned to the circle form the australopithecines and therefore be described as Australopithecus habilis, a new impetus. For example, have also analyzes the construction of the teeth and limbs as well as the eating habits result in a greater proximity of Homo habilis Australopithecus than to Homo ergaster / Homo erectus. However, for example, from an analysis of the nature of the tooth KB was 5223 closed from Kromdraai (South Africa), that the food of Homo habilis - unlike those of Australopithecus africanus - was made flesh in significantly greater extent and thus the habits of other species of the genus Homo was like.