Hominids with a brain absolutely and relatively larger than that of the australopithecines appeared about 2.3 million years ago. These hominids are classified in our own genus: Homo. The earliest species to appear was the Homo Habilis. It was the first of our ancestors to show a significant increase in brain size and also the first to be found associated with stone tools. These characteristics resulted in this species’ placement into the human genus, Homo. Discovery
The first fossil was found in 1960 when a team led by scientists Louis and Mary Leakey uncovered the fossilized remains of a unique early human at Olduvai Gorge in Tanzania. Because this early human had a combination of features different from those seen in Australopithecus, Louis Leakey, South African scientist Philip Tobias, and British scientist John Napier called these remains a new species: Homo habilis, meaning ‘handy man', because they suspected that it was this slightly larger-brained early human that made the thousands of stone tools also found at Olduvai Gorge. Physical Features
Homo habilis had a larger brain than earlier human ancestors (Australopithecus) and this is reflected in significant changes to the shape of the skull. However, many other features including limb proportions are similar to those of the earlier australopithecine ancestors. Body, size and shape:
* Most of the body was covered by fur.
* Body proportions were similar to those of australopithecines with females growing to about 117 (3,8 feet tall) centimeters and males to about 144 centimeters in height (4,7 feet tall). * They may have also been sexually dimorphic like the australopithecines, as individuals seem to have greatly differed in size.
* About 47 kg (103 pounds) in males and 34 kg in females (75 pounds). Brain:
* Cranial capacity: 600-800 cc brain
* The average was 630-640 cubic centimeters in size, representing 1.7 % of their body weight. This was a significant increase compared to australopithecine brains.
* Brain case had become fuller and more rounded due to expansion of the brain. * Beginnings of a slight forehead were appearing
* Face had a small, arched brow ridge and was smaller and shorter than those of earlier ancestors. * The hole for the spinal cord was located in the center of the skull base, showing that this species walked on two legs (bipedalism). * Facial projection was reduced compared with earlier species.
Jaws and teeth:
* Jaw was smaller than those found in the earlier australopithecines. * Teeth were arranged in a more rounded arc like those of modern humans * Teeth had become smaller and more human-like. The back teeth were smaller relative to front teeth, a great difference from Australopithecus afarensis in which the back teeth were large compared to the front teeth.
* Features of the leg and foot bones indicate that this species walked on two legs. * Legs were relatively short, providing this species with arm and leg proportions that were relatively ape-like and similar to those of the australopithecines. * Powerful hands and relatively long arms, suggesting that they were at least partially arboreal. * Finger bones were slightly curved and intermediate in shape between the curved finger bones of quadrupedal apes and the straight finger bones of modern humans. * Finger bone proportions suggest the human-like ability to form a precision grip.
Homo habilis lived from approximately 2.3 to 1.4 million years ago, during the Gelasian Pleistocene period. This species was assumed to have lived in southern and northeastern parts of Africa. The fossils were specifically found in Lake Turkana, Kenya and Olduvai Gorge, Tanzania. Homo habilis sites include: Olduvai Gorge, Tanzania; Koobi Fora, Lake Turkana, and Tugen Hills, Kenya; Sterkfontein and Taung, South Africa; Hadar and Omo Valley, Ethiopia....