Homo habilis

Homo habilis, an extinct species of early human that lived in Africa from about 1.9 million to 1.5 million years ago. H. habilis is one of the earliest known members of the genus Homo, the branch of the human family tree believed to have evolved into modern humans (see Human Evolution). The term Homo habilis means handy man, a name selected for the primitive stone tools found near H. habilis fossils.

Scientists distinguished H. habilis from australopithecines, the more primitive early humans from which it evolved, by analyzing key physical characteristics. H. habilis was thought to have a larger brain than australopithecines. The braincase of H. habilis measured from 590 to 690 cubic centimeters (36 to 42 cu inches), well above the australopithecine range of 390 to 550 cu cm (24 to 34 cu in). Australopithecines had long arms and short legs, similar to the limbs of apes. The overall body form of australopithecines was also apelike in having large body bulk relative to its height. Some H. habilis specimens retain these apelike body proportions, but other specimens appear more humanlike, with a smaller body bulk relative to height. H. habilis had smaller cheek teeth (molars) and a less protruding face than earlier human species.

The use of primitive tools implies that H. habilis had developed a different way of gathering food than earlier human species, most of which probably fed primarily on vegetation. H. habilis probably ate meat as well as fruits and vegetables. Anthropologists disagree on whether H. habilis obtained this meat through hunting, scavenging, or a combination of both techniques.

The first fossil evidence of H. habilis was discovered in 1960 at Olduvai Gorge in northern Tanzania by a team led by paleoanthropologists Louis Leakey and Mary Leakey. Additional specimens were discovered from 1960 to 1963. The species was named in 1964 after analysis of these fossils by Louis Leakey, South African paleoanthropologist Philip Tobias, and British primate researcher John Napier. Other anthropologists have since identified specimens in northern Kenya, South Africa, and Malawi. Although all of these specimens had larger brains than australopithecines, some had especially large brains (almost 800 cu cm or 49 cu in) and more modern skeletons. However, their large and slightly protruding faces seem more primitive than those of other H. habilis specimens. Most scientists now believe that these fossils represent a distinct species named Homo rudolfensis.

Even without including the H. rudolfensis specimens, the fossils classified as H. habilis make up a rather miscellaneous assemblage. This ambiguity makes it difficult for scientists to determine where within this assortment of fossils the origin of later humans lies—if, indeed, it does lie among any of the forms so far discovered.