Homo habilis

13-3 Homo habilis

Humans (Homo sapiens sapiens) are classified within the genus Homo (a single genus can have several species). There have been three traditional members of the Homo genus: Homo sapiens, Homo neanderthalensis, and Homo erectus. After the discovery of Homo rudolfensis (2.4–1.9 Ma) and Homo habilis (2.4–1.4 Ma) fossils, these species were added to the Homo genus; however, there is still some controversy over whether these two species should be classified as Homo. 

There were three traditional members of the Homo genus: Homo sapiens, Homo neanderthalensis, and Homo erectus. After the discovery of Homo rudolfensis (2.4–1.9 Ma) and Homo habilis (2.4–1.4 Ma) fossils, these species were added to the Homo genus; however, there is still some controversy over whether these two species should be classified as Homo. Homo habilis (Figure 13‑10) was found by the Leakey’s in the 1960s. The Leakeys classified Homo habilis as a member of the Homo genus because they were bipedal, had an upright posture, and made tools.

Although there had been doubt about the evolutionary relationship between Australopithecus and Homo habilis, Australopithecus sediba now bridges the gap between them.[1] Homo habilis still had a somewhat apelike face, but less so than Australopithecus. They also had smaller teeth, which means that they probably did not consume as much tough food such as brittle nuts and hard tubers. Homo habilis was the first Homo species, albeit controversial. Paranthropus boisei (2.6–1.2 Ma) was discovered in 1959 by Mary Leakey in the Olduvai Gorge in Tanzania. Paranthropus was a contemporary of australopithecines, and like the australopithecines, they were approximately 4 ft tall; however, they had a much larger brain (500–550 cc) and were heavier (68 kg). The males were much larger than the females. Although they appear to be transitional early Homo species, they were not ancestral to the Homo genus. From two fossils dated 1.9 Ma, the Homo habilis brain grew up to 750 cc, which was 80% larger than Australopithecus afarensis.

There were three traditional members of the Homo genus: Homo sapiens, Homo neanderthalensis, and Homo erectus. After the discovery of Homo rudolfensis (2.4–1.9 Ma) and Homo habilis (2.4–1.4 Ma) fossils, these species were added to the Homo genus; however, there is still some controversy over whether these two species should be classified as Homo. Homo habilis (Figure 13-10) was found by the Leakey’s in the 1960s. The Leakeys classified Homo habilis as a member of the Homo genus because they were bipedal, had an upright posture, and made tools.

Tool use distinguishes humans from other species (video below). The oldest tools have been found in sediments in Olduvai Gorge. The Leakeys found the stone tools many years before they discovered Homo habilis. The tools were made from rounded river rock. They struck the river rock with a hammer stone and the flakes that broke off where sharp and could be used to cut meat. Although Homo habilis were similar to Australopithecus in stature; they had much larger brains (600 cc) than Australopithecus (400 cc). Notice the expanded upper braincase in Figure 13-21. Fossils of both have been found at Lake Turkana in East Africa. Homo habilis, was found one year after the discovery of Paranthropus boisei by Louis and Mary Leakey in 1960. These species had a smaller face and teeth than the Paranthropus boisei.   

The name Homo habilis, ‘handy man,’ referred to the fact that Homo habilis manufactured and used stone tools. Thousands of stone tools were found in the Olduvai Gorge along with Homo habilis fossils. They probably used tools to cut into and scrape meat and body parts out of carcasses off dead animals before other carnivores could find the carcass. They also accessed bone marrow by breaking bones with hammer tools. The marrow is thought to have provided energy for an increasing brain size.  The evidence for this is bones that look like they have been broken by a hammer tool in Olduvai Gorge. Tools enabled them to compete with other carnivores for meat, unlike their chimp relatives, which stayed far away from carcasses due to their fear of dangerous carnivores.

Homo habilis might have built simple huts consisting of rock piles with poles held up by the rock piles. Olduwan tools were extremely simple and did not require preplanning. Thus, they do not indicate a high level of cognition in Homo habilis; however, the Olduwan stone tools are considered to be the earliest evidence of human culture.

Homo habilis was quite social. They probably lived in groups of 70 to 85. The large population probably helped them scare small predators, such as jackals and cheetahs, away from animals they had killed so that Homo habilis could scavenge the carcasses. They had a smaller mandible and canines, which indicates they used tools to break down their food. Bones had cutmarks, which indicates marrow eating. The consumption of meat probably resulted in a decrease in the size of the gut, which allowed more energy from the increasing brain size. Scientists are not sure whether Homo habilis could run long distances, which would have been required for hunting.

References

[1] Pickering, Robyn, Paul HGM Dirks, Zubair Jinnah, Darryl J. De Ruiter, Steven E. Churchill, Andy IR Herries, Jon D. Woodhead, John C. Hellstrom, and Lee R. Berger. "Australopithecus sediba at 1.977 Ma and implications for the origins of the genus Homo." science 333, no. 6048 (2011): 1421-1423.

[2] Bill Sellars, “Tool use” Accessed at  http://www.leeds.ac.uk/chb/lectures/anthl_12.html

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Olduwan choppers. Credit Didier Descouens. Used here per CC BY-SA 4.0