Homo habilis. Classification as Homo

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1 Homo habilis Homo habilis is a species of the tribe Hominini, during the Gelasian and early Calabrian stages of the Pleistocene period, between roughly 2.8 and 1.5 million years ago. In its appearance and morphology, H. habilis is the least similar to modern humans of all species in the genus Homo (except the equally controversial H. rudolfensis), and its classification as Homo has been the subject of controversial debate since its first proposal in the 1960s. Classification as Homo There has been scholarly debate regarding its placement in the genus Homo rather than the genus Australopithecus. The small size and rather primitive attributes have led some experts (Richard Leakey among them) to propose excluding H. habilis from the genus Homo and placing them instead in Australopithecus as Australopithecus habilis. Louis Leakey, the British-Kenyan paleoanthropologist to suggest the existence of H. habilis, and his wife, Mary Leakey, found the first trace of H. habilis in 1955: two hominin teeth. It is later classified as "milk teeth", and therefore considered difficult to link to taxa unlike permanent teeth. However in 1959, Mary Leakey recovered the cranium of a young adult which had: a small brain, large face, tiny canines and massive chewing teeth (which earned it the nickname of "The Nutcracker man"). H. habilis was short and had disproportionately long arms compared to modern humans; however, it had a less protruding face than the australopithecines from which it is thought to have descended. H. habilis had a cranial capacity slightly less than half of the size of modern humans. Despite the ape-like morphology of the bodies, H. habilis remains are often accompanied by primitive stone tools (e.g. Olduvai Gorge, Tanzania and Lake Turkana, Kenya). Homo habilis has often been thought to be the ancestor of the more gracile and sophisticated Homo ergaster, which in turn gave rise to the more human-appearing species, Homo erectus. Debates continue over whether all of the known fossils are properly attributed to the species, and some paleoanthropologists regard the taxon as invalid, made up of fossil specimens of Australopithecus and Homo. New findings in

2 2007 seemed to confirm the view that H. habilis and H. erectus coexisted, representing separate lineages from a common ancestor instead of H. erectus being descended from H. habilis. An alternative explanation would be that any ancestral relationship from H. habilis to H. erectus would have to have been cladogenetic rather than anagenetic (meaning that if an isolated subgroup population of H. habilis became the ancestor of H. erectus, other subgroups remained as unchanged H. habilis until their much later extinction). Its brain size has been shown to range from 550 cm3 to 687 cm3, rather than from 363 cm3 to 600 cm3 as formerly thought. A virtual reconstruction for the better published in 2015 estimated the endocranial volume at between 729 and 824 ml, larger than any previously published value. H. habilis' brain capacity of around 640 cm³ was on average 50% larger than australopithecines, but considerably smaller than the 1350 to 1450 cm³ range of modern Homo sapiens. These hominins were smaller than modern humans, on average standing no more than 1.3 m (4 ft 3 in) tall. A fragment of fossilized jawbone, dated to around 2.8 million years ago, was discovered in the Ledi-Geraru research area in Afar Regional State in The fossil is considered the earliest evidence of the Homo genus known to date, and seems to be intermediate between Australopithecus and H. habilis. The individual in question lived just after a major climate shift in the region, when forests and waterways were rapidly replaced by arid savannah. Fossils Skull of Homo habilis, Indian Museum-Paranthropus boisei

3 OH 62 One set of fossil remains (OH 62), discovered by Donald Johanson and Tim White in Olduvai Gorge in 1986, included the important upper and lower limbs. Their finding stimulated some debate at the time. Skull of KNM ER KNM ER 1813 KNM ER 1813 is a relatively complete cranium which dates to 1.9 million years old, discovered at Koobi Fora, Kenya by Kamoya Kimeu in The brain capacity is 510 cm³, not as impressive as other early specimen and forms of H. habilis discovered. OH 24 OH 24 (Twiggy) is a roughly deformed cranium about 1.8 million years old discovered in October 1968 at Olduvai Gorge, Tanzania. The brain volume is just under 600 cm³; also a reduction in a protruding face is present compared to members of more primitive australopithecines. OH 7 OH 7 dates to 1.75 million years old, and was discovered by Mary and Louis Leakey on November 4, 1960 at Olduvai Gorge, Tanzania. It is a lower jaw complete with teeth; due to the size of the small teeth,

4 researchers estimate this juvenile individual had a brain volume of 363 cm³. Also found were more than 20 fragments of the left hand. Tobias and Napier assisted in classifying OH 7 as the type fossil. KNM ER 180 KNM ER 1805 is a specimen of an adult H. habilis made of three pieces of cranium dating to 1.74 million years old from Koobi Fora, Kenya. Previous assumptions were that this specimen belongs to H. erectus based on the degree of prognathism and overall cranial shape. Interpretations Homo habilis - Forensic facial reconstruction/approximation

5 Homo habilis is thought to have mastered the Lower Paleolithic Olduwan tool set which used stone flakes. H. habilis used these stones to butcher animals and to skin the animals. These stone flakes were more advanced than any tools previously used, and gave H. habilis the edge it needed to prosper in hostile environments previously too formidable for primates. Whether H. habilis was the first hominid to master stone tool technology remains controversial, as Australopithecus garhi, dated to 2.6 million years ago, has been found along with stone tool implements. Most experts assume the intelligence and social organization of H. habilis were more sophisticated than typical australopithecines or chimpanzees. H. habilis used tools primarily for scavenging, such as cleaving meat off carrion, rather than defense or hunting. Yet despite tool usage, H. habilis was not the master hunter its sister species (or descendants) proved to be, as ample fossil evidence indicates H. habilis was a staple in the diet of large predatory animals, such as Dinofelis, a large scimitar-toothed predatory cat the size of a jaguar. Homo habilis coexisted with other Homo-like bipedal primates, such as Paranthropus boisei, some of which prospered for many millennia. However, H. habilis, possibly because of its early tool innovation and a less specialized diet, became the precursor of an entire line of new species, whereas Paranthropus boisei and its robust relatives disappeared from the fossil record. H. habilis may also have coexisted with H. erectus in Africa for a period of 500,000 years. References Early Humans (Roy A. Gallant)/Copyright 2000 ISBN The Making of Mankind, Richard E. Leakey, Elsevier-Dutton Publishing Company, Inc., Copyright 1981, ISBN , LC Catalog Number A New Species of Genus Homo from Olduvai Gorge (PDF), L.S.B. Leakey; P.V. Tobias; J.R. Napier, Current Anthropology, Vol.6, No.4, (Oct 1965) Fifty Years After Homo habilis (PDF), Bernard Wood, Nature, Vol. 508, (3 April, 2014) Article Source:

6 Photo Attributions "KNM-ER 1470 & 1813" by Conty - Own work. Licensed under CC BY 3.0 via Commons - ER_1470_%26_1813.png#/media/File:KNM-ER_1470_%26_1813.png "Skull of Homo Habilis, Indian Museum, Kolkata" by Royroydeb - Own work. Licensed under CC BY-SA 4.0 via Commons - ian_museum,_kolkata.jpg#/media/file:skull_of_homo_habilis,_indian _Museum,_Kolkata.jpg "Homo habilis-knm ER 1813" by José-Manuel Benito Álvarez (España) > Locutus Borg - Own work. Licensed under Public Domain via Commons - KNM_ER_1813.jpg#/media/File:Homo_habilis-KNM_ER_1813.jpg "Homo habilis" by Author of reconstruction unknown (klimaundmensch.de)photographed by User:Lillyundfreya - Photographed at Westfälisches Museum für Archäologie, Herne. Licensed under CC BY-SA 3.0 via Commons - ile:homo_habilis.jpg "Homo habilis - forensic facial reconstruction" by Cicero Moraes - Own work. Licensed under CC BY-SA 3.0 via Commons - _forensic_facial_reconstruction.png#/media/file:homo_habilis_- _forensic_facial_reconstruction.png