Homo habilis

Homo habilis (from the Latin homo, 'man', and habilis, 'skilled') is a species of archaic human from the Lower Pleistocene. It lived in southern and eastern Africa about 2.3 to 1.65 million years ago. After the description of the species in 1964, Homo habilis was highly controversial and many researchers recommended that it be synonymized with Australopithecus africanus , the only known hominid at that time. However, Homo habilis received more recognition as time passed and new discoveries were made. In the 1980s it was proposed that Homo habilis was a human ancestor that evolved directly into Homo erectus, in the direct line of modern humans. This point of view is now the subject of debate. Several specimens of unidentified species were assigned to Homo habilis, which generated arguments for its division into “Homo rudolfensis” and “Homo gautengensis”, of which only the first received broad support.^{[citation needed]}

The denomination habilis was suggested by Raymond Dart, due to its association with concepts such as skilful, vigorous and mentally capable, and refers to the discovery of lithic instruments probably made by him. Detailed studies of the skeletal remains of his hands have been carried out to verify whether it would really be possible for this Homo to have made them. The scientists concluded that he was capable of using grip pressure to perform the necessary manipulations in the manufacture of stone utensils; it was probably an opportunistic carnivore, that is, a scavenger.

A significant increase in brain size is observed in them with respect to Australopithecus, which has been calculated between 510 cm³ and 600 cm³ (from KNM-ER 1813) and 800 cm³ (from OH 24).

Most of the remains have been found in Kenya, in the town of Koobi Fora and in Tanzania, in the well-known Olduvai Gorge.

Some authors question its belonging to Homo, in accordance with a restrictive interpretation of the diagnosis of the genus, and assign it either to Australopithecus or propose that it a new genus is defined for this species in which Homo rudolfensis is also included.

Physical characteristics

The main characteristics are the following:

• More rounded skull.
• Spadiform incisors.
• Large molars and thick enamel.
• Absence of diastema (separation between premolars and canines).
• Foramen magnum (occipital bone) located more towards the center.
• Feature less prognate than australopitecinos (short face).
• Larger incisors than australopithecinos.
• Fingers curved of feet and hands (which indicated that they still used the trees).
• The biped position in females causes a reduction in the pelvis that results in the advancement of childbirth (which implies premature neonate, a longer time dedicated to parenting and thus the need to maintain strong social ties that potentially contribute to the development of a culture).
• Higher cranial capacity: 500 to ~800 cm3

Differences from Australopithecines

Homo habilisForensic facial reconstruction by Cicero Moraes.

Analyzing some of the recovered bone remains, it can be recognized that it is a species with a much more human appearance than that found in australopithecines. The head of the femur is larger, shorter, and rounded. Also the pelvis has a more modern look.

Its height was similar to that of Australopithecus africanus, about 1.3 m and an average weight of 52 kg for males and 32 kg for females.

Homo habilis and Homo erectus

Findings made in Northeast Africa (Lake Turkana area) by Louise and Meave Leakey (daughters of Louis and Mary Leakey) published in 2007 bring the existence of Homo habilis closer to more recent dates: up to at least 1 440 000 years before present, such dating implies that for at least 500 000 years Homo habilis and Homo erectus, the researchers believe that initially there should not have been major conflicts between the two species, however, the growth of the Homo erectus population would have ended with a struggle for resources from which Homo erectus would have emerged triumphant. On the other hand, this same finding casts doubt on a direct relationship between both species. Although there are authors such as Erik Trinkaus who believe that coexistence does not rule out that Homo habilis was a direct ancestor of H. erectus.

Main deposits and fossil remains

Kada Hadar (Ethiopia)

• AL 666-1: Part of the skull with teeth with 2.33 Ma of antiquity. It would be habilis older if confirmed, since there are doubts in the attribution.

Shungura-Omo (Ethiopia)

• OMO 75-14: Upper jaw with part of the teeth and some parts of the skull of 2,12 Ma. Your usual attribution is to Homo rudolfensis although he is in doubt.
• L894-I: Partial Cranium, more greasy than OMO 75-14, but also with attribution doubts. Datad at 1.88 Ma.

Chemeron (Kenia)

• KNM-BC 1 or temporary Chemeeron: Part of a temporary bone of a skull of an antique of 2.4 Ma. Duties of attribution between Homo habilis, Homo rudolfensis u Homo sp.

Koobi Fora (Kenia)

• KNM-ER 1805: Three pieces of skull of an adult individual, dated in 1.74 Ma;
• KNM-ER 1813: Very complete cranium of 510 cm3 of capacity and dated in 1.78 Ma. Discovered by Kamoya Kimeu in 1973.

(KNM-ER 1470 or Rudy, initially interpreted as Homo habilis, is currently assigned to a different species, Homo rudolfensis).

Olduvai Gorges (Tanzania)

• OH 7: Lower jaw with 13 teeth, a lower molar, two legs and 21 finger bones, hand and left wrist. This set of fossils is the Holotype of the species. The cranial capacity has been estimated by different researchers between 363 and 710 cm3. The remains belonged to a young male, 12 or 13 years old and have been dated in 1.75 Ma. They were discovered by Jonathan and Mary Leakey in 1960. Homo habilis was described on the basis of these remains in 1964 by Louis Leakey, Tobias and Napier.
• OH 8: Most of the bones of a foot of 1.75 Ma. It could probably be related to OH 10 and, with more doubts, to OH 35.
• OH 13 o Cinderella: Fragments of jaw, maxillary and teeth of a possible female, dated in 1.7 Ma. Discovered by N. Mbuika in 1963.
• OH 16 or George: Calota of a habilis 1.7 Ma.
• OH 24 o Twiggy: A skull, which was found very deformed. After the restoration a capacity of less than 600 cm3 has been estimated. It was located by Peter Nzube in 1968.
• OH 35: Tibia of 1.8 million years. OH 35 could be part of the same individual as other fossils, OH 8 and OH 10, although there are more doubts than in their relationship.
• OH 62 u Dik-dik hominid: Set of fossil remains that includes superior and lower members, discovered by Donald Johanson and Tim White in 1986.
• OH 65: Upper jaw with most teeth, found Amy Cushing and Agustino Venance in 1995.

Sterkfontein (South Africa)

• StW 53: A skull, located in the "Member 5" and dated in 1.8 Ma and whose attribute to habilis It's doubtful. It has been classified as well Homo habilis sensu latoHolotype of Homo gautengensis or, simply, without classifying.

Swartkrans (South Africa)

• SK 847: A partial skull that includes left side of the face and temporary part of the upper jaw. Shows own characteristics of H. ergaster and others H. habilisWhat led him to be listed as: Homo habilis sensu lato, Homo without sorting, and even at first, Austrolapithecus robustus. This fossil has allowed, together with others, to study the evolution of the ear (Spoor et al.1994).