Final answer:
The genus Homo, which includes modern humans and extinct Homo species, is distinguished by brain size exceeding 600 cc, proficient tool use, reduced prognathism, skeleton adapted for bipedal walking, and a particular bone structure in hands for dexterity necessary for tool-making.
Step-by-step explanation:
How is the Genus Homo Distinguished?
The genus Homo is a classification within the Hominidae family that includes humans and several extinct related species. Distinctive criteria for classifying a species under the genus Homo, beyond bipedalism, include several evolutionary traits identified by pioneering paleoanthropologists. Mary Leakey, Louis Leakey, and John Napier, along with primatologist Phillip Tobias, were instrumental in establishing these criteria with their extensive study of Homo habilis.
Criteria for Classification:
Based on research, the Leakeys and Napier proposed the following criteria for classifying Homo: a brain size over 600 cc; a round, globular skull; proficient tool use; reduced prognathism and smaller jaws; humanlike postcranial features, including feet that are fully adapted for bipedal walking. The genus Homo evolved features that represented a significant departure from earlier hominins, such as australopithecines. This includes a larger brain size, which for H. habilis, ranged between 600 to 750 cubic centimeters. Moreover, the genus Homo exhibited significant changes in hand bone structure, which allowed for increased dexterity necessary for tool-making, and the fingers and thumbs were positioned for a better grip.