This hominid species is among the oldest/earliest of the genus Homo ("human") known to paleoanthropologists in the fossil record, dating from about 2.4 to about 1.75 MYA (million years ago), at which time it quickly - in paleoanthropological terms - evolved per the current consensus model into the species Homo ergaster.
Both these fossil species are viewed as probably ancestral to modern humans. The species Homo habilis is very close in form to its likely ancestral population, Australopithecus africanus, the only difference being that early Homo species had slightly larger cranial capacities. This skull, which was probably female, tests out at about 600 ml., as compared to a typical brain size of 450 ml. for Australopithecus africanus, versus an average for modern humans of about 1350 ml.
As was true of the australopiths generally, the earliest Homo species showed much greater sexual dimorphism than is found among contemporary humans, with the adult females averaging about 3 1/2 feet in height, and the males about 5 feet tall.
The consensus among paleoanthropologists is that it was one or more of the earliest Homo species, including Homo habilis, that manufactured the first stone tools, the so-called "pebble tools" and their associated flakes, known as the Oldowan tool tradition.
This fossil was found at the base of the Olduvai Gorge in Tanzania and has a potassium-argon date of 1.8 MY. This individual carries the nickname "Twiggy" and the catalog number OH 24; it was found in 1968 by Peter Nzube.