Homo habilishominid (Latin: “able man” or “handy man”)

Apart from the original discovery of the jaw, cranial, and hand bones from a juvenile individual called Olduvai Hominid 7 (OH 7), additional fossils from Olduvai have been ascribed to H. habilis. Pieces of another thin-walled cranium along with upper and lower jaws and teeth came to light in 1963. Just a month later a third skull was found, but these bones had been trampled by cattle after being washed into a gully. Some of the teeth survived, but the cranium was broken into many small fragments; only the top of the braincase, or vault, has been pieced back together. These two skulls are called OH 13 and OH 16.

Since 1964 more material has been discovered, not only at Olduvai but at other African localities as well. One intriguing specimen is OH 24. This cranium is more complete than others from Olduvai. Because some of the bones are crushed and distorted, however, the face and braincase are warped. OH 24 may differ from Australopithecus in brain size and dental characteristics, but it resembles the australopiths of southern Africa in other features, such as the shape of the face. Complete agreement concerning its significance has not been reached, partly because the fossil is damaged.

Important discoveries made in the Koobi Fora region of northern Kenya include a controversial skull called KNM-ER 1470 (Kenya National Museum–East Rudolf), which resembles both Australopithecus and Homo. As in the case of OH 16, this specimen had been broken into many fragments, which could be collected only after extensive sieving of the deposits. Some of the pieces were then fitted into the reconstruction of a face and much of a large vault. Brain volume can be measured rather accurately and is about 750 cc (46 cubic inches). This evidence prompted some paleoanthropologists to describe ER 1470 as one of the most ancient undoubted representatives of the genus Homo because some other features of the braincase are also Homo-like. At the same time, it is apparent that the facial skeleton is relatively large and flattened in its lower parts. In this respect, the Koobi Fora specimen resembles Australopithecus anatomically.

Among other key finds from the Koobi Fora region are KNM-ER 1813 and KNM-ER 1805. The former, which is most of a cranium, is smaller than ER 1470 and resembles OH 13 in many details, including tooth size and morphology. The latter skull exhibits some peculiar features. Although the braincase of ER 1805 is close to 600 cc in volume and is thus expanded moderately beyond the size expected in Australopithecus, a bony crest runs along the top of the skull. This sagittal crest is coupled with another prominent crest oriented across the rear of the skull. These ridges indicate that the chewing muscles and neck muscles were powerfully developed. A similar if more exaggerated pattern of cresting appears in the so-called robust australopiths but not in Homo. Other features of ER 1805, however, are Homo-like. As a result, there has been disagreement among anatomists regarding the hominin species to which this individual should be assigned. Despite its anomalies, ER 1805 is often discussed along with other specimens grouped as H. habilis.

Several mandibles resembling that of OH 7 have been recovered from the Koobi Fora area, and teeth that may belong to H. habilis have been found farther to the north, in the Omo River valley of Ethiopia. Some additional material, including a badly broken cranium, are known from the cave at Swartkrans in South Africa. At Swartkrans the fossils are mixed with many other bones of robust australopiths. An early species of Homo may also be present at Sterkfontein, not far from Swartkrans. Here again the remains are fragmentary and not particularly informative.

A more valuable discovery was reported from Olduvai Gorge in 1986. A jaw with teeth and skull fragments as well as pieces of a right arm and both legs were found. The bones seem to represent one individual, called OH 62. Although the skull is shattered, enough of the face is preserved to suggest similarities to early Homo. The find is especially important because of the limbs, which show that OH 62 was a very small hominin. The arm is long relative to the leg, resulting in body proportions that differ dramatically from those of more modern hominins.