Several specimens with insecure species identification were assigned to H. habilis, leading to arguments for splitting, namely into "H. rudolfensis" and "H. gautengensis" of which only the former has received wide support.

The body proportions of H. habilis are only known from two highly fragmentary skeletons, and is based largely on assuming a similar anatomy to the earlier australopithecines.

This configuration would be advantageous with multiple males to defend against open savanna predators, such as big cats, hyenas and crocodiles.

However, the actual first remains—OH 4, a molar—were discovered by the senior assistant of Louis and Mary Leakey (Jonathan's parents), Heselon Mukiri, other native Africans, in 1959, but this was not realised at the time.

[2] In 1964, Louis, South African palaeoanthropologist Phillip V. Tobias, and British primatologist John R. Napier officially assigned the remains into the genus Homo, and, on recommendation by Australian anthropologist Raymond Dart, the specific name H. habilis, meaning "able, handy, mentally skillful, vigorous" in Latin.

[6] Many had accepted Tobias' model and assigned Late Pliocene to Early Pleistocene hominin remains outside the range of Paranthropus and H. erectus into H. habilis.

To address this controversy, English palaeoanthropologist Bernard Wood proposed in 1985, that the comparatively massive skull KNM-ER 1470 from Lake Turkana, Kenya, discovered in 1972 and assigned to H. habilis, actually represented a different species,[8] now referred to as Homo rudolfensis.

[9] Early Homo from South Africa have variously been assigned to H. habilis or H. ergaster / H. erectus, but species designation has largely been unclear.

The discovery of LD 350-1, the oldest Homo specimen, dating to 2.8 mya, in the Afar Region of Ethiopia may indicate that the genus evolved from A. afarensis around this time.

This specimen was initially classified as Homo sp.,[23] though subsequent studies have suggested that it also shares characteristics with Australopithecus and that it is clearly distinct from H.

[29] The tooth rows of H. habilis were V-shaped as opposed to U-shaped in later Homo, and the mouth jutted outwards (was prognathic), though the face was flat from the nose up.

[31] It is generally assumed that pre-H. ergaster hominins, including H. habilis, exhibited notable sexual dimorphism with males markedly bigger than females.

The thickness of the limb bones in OH 62 is more similar to chimpanzees than H. ergaster / H. erectus and modern humans, which may indicate different load bearing capabilities more suitable for arboreality in H.

[41] The spatial distribution of tools and processed animal bones at the FLK Zinj and PTK sites in Olduvai Gorge indicate the inhabitants used this area as a communal butchering and eating grounds, as opposed to the nuclear family system of modern hunter gatherers where the group is subdivided into smaller units each with their own butchering and eating grounds.

[43] The left foot OH 8 seems to have been bitten off by a crocodile,[44] possibly Crocodylus anthropophagus,[45] and the leg OH 35, which either belongs to P. boisei or H. habilis, shows evidence of leopard predation.

[44] H. habilis and contemporary hominins were likely predated upon by other large carnivores of the time, such as (in Olduvai Gorge) the hunting hyena Chasmaporthetes nitidula, and the saber-toothed cats Dinofelis and Megantereon.

[4] However, when describing P. boisei five years earlier, Louis Leakey said, "There is no reason whatever, in this case, to believe that the skull represents the victim of a cannibalistic feast by some hypothetical more advanced type of man.

[55] It is typically thought that the diets of H. habilis and other early Homo had a greater proportion of meat than Australopithecus, and that this led to brain growth.

The main hypotheses regarding this are: meat is energy- and nutrient-rich and put evolutionary pressure on developing enhanced cognitive skills to facilitate strategic scavenging and monopolise fresh carcasses, or meat allowed the large and calorie-expensive ape gut to decrease in size allowing this energy to be diverted to brain growth.

Nonetheless, the proposed food-gathering models to explain large brain growth necessitate increased daily travel distance.

The bodies of the mandibles of H. habilis and other early Homo are thicker than those of modern humans and all living apes, more comparable to Australopithecus.

The mandibular body resists torsion from the bite force or chewing, meaning their jaws could produce unusually powerful stresses while eating.

Individuals likely used these tools primarily to butcher and skin animals and crush bones, but also sometimes to saw and scrape wood and cut soft plants.

Knappers – individuals shaping stones – appear to have carefully selected lithic cores and knew that certain rocks would break in a specific way when struck hard enough and on the right spot, and they produced several different types, including choppers, polyhedrons, and discoids.

Nonetheless, specific shapes were likely not thought of in advance, and probably stem from a lack of standardisation in producing such tools as well as the types of raw materials at the knappers' disposal.

Since then, more discoveries have placed the origins of material culture substantially backwards in time,[4] with the Oldowan being discovered in Ledi-Geraru and Gona in Ethiopia dating to 2.6 mya, perhaps associated with the evolution of the genus.

[60] Nonetheless, the comparatively sharp-edged Oldowan culture was a major innovation from australopithecine technology, and it would have allowed different feeding strategies and the ability to process a wider range of foods, which would have been advantageous in the changing climate of the time.

[58] It is unclear if the Oldowan was independently invented or if it was the result of hominin experimentation with rocks over hundreds of thousands of years across multiple species.