Question

Describe the skeletal anatomy of Homo habilis and Homo erectus. What are their similarities and differences and which one shows more amounts of variation?

Answer 1

Homo habilis:

• Olduvai and Koobi Fora fossils have allowed researchers to make some determinations about the anatomy of early humans. It is clear that the braincase of H. habilis is larger than that of Australopithecus. The original finds from Olduvai Gorge include two sizable bones from the skull of OH 7. An incomplete brain cast was molded by putting the bones together to form a partial cranium. This cast has been used to estimate a total brain volume of about 680 cc. A brain cast from ER 1470, which has a more-complete cranium, can be measured directly; its volume is about 775 cc. One or two additional fragmentary skulls appear to be about the same size as that of ER 1470. Others are much smaller—such as ER 1813, which has a cranial capacity of only about 510 cc (31.1 cubic inches). Thus, brain sizes ranging from slightly more than 500 to nearly 800 cc (30.5 to nearly 48.8 cubic inches) seem to characterize H. habilis.
• The facial bones of several specimens are at least partly preserved, and facial proportions vary considerably. One of the Olduvai hominins, OH 24, seems anatomically similar to Australopithecus in having prominent cheekbones and a flat nasal region. This gives the central region of the face a depressed, or “dished,” appearance, and the upper part of the nasal profile is obscured by the cheek when the specimen is viewed from the side. Such hollowing of the face is characteristic of some South African australopiths but is not seen in later Homo. The facial skeleton of ER 1470 is large relative to the braincase, and it shows flattening below the nose—Australopithecus-like features. The walls of the nasal opening, however, are slightly everted, and there is at least an indication that the nose stands out in more relief than would be expected in australopiths. The face of ER 1813 is even more modern.
• The front teeth of H. habilis are not much different in size from those of Australopithecus, but the premolar and molar crowns—particularly in the lower jaw—are narrower. The jaw itself may be quite heavily constructed like that of gracile australopiths. This is the case for OH 7 and also for at least one specimen from koobi fora.
• Only a few other skeletal parts have been discovered. Some limb bones from Olduvai and Koobi Fora have been grouped tentatively with H. habilis on the basis of general anatomic similarity to later humans. These fossils, however, are not associated with any teeth or skulls, and it is probably not appropriate to use them as the basis for describing early Homo. One individual for which body parts are more fully represented is OH 62. Arm and leg bones of OH 62 are fragmentary, but the arm is relatively long. The skeleton may be similar in its proportions to small australopiths. OH 62 probably walked on two legs as efficiently as other early hominins, but this diminutive individual was unlike later humans in many respects.

Homo erectus:

Much of the fossil material discovered in Java and China consists of cranial bones, jawbones, and teeth. The few broken limb bones found at Zhoukoudian have provided little information. It is possible that the complete femur excavated by Dubois at Trinil is more recent in age than the other fossils found there and not attributable to H. erectus. It comes as no surprise, therefore, that the greatest descriptive emphasis has been on the shape of the skull rather than other parts of the skeleton. The continuing discoveries in Africa (particularly at the Olduvai and Lake Turkana sites) have yielded a more complete picture of H. erectus anatomy.

• The cranium of H. erectus, with its low profile and average endocranial (brain) capacity of less than 1,000 cubic cm (61 cubic inches), is distinctly different from that of other humans. The average endocranial capacity of modern Homo sapiens, for example, is 1,350 cubic cm, although the range for recent humans is appreciable, perhaps 1,000 to 2,000 cubic cm. The upper part of the maximum estimated range for H. erectus endocranial capacity (1,200 cubic cm) thus overlaps with the lower values expected for Homo sapiens.
• Some difference in estimated brain size is apparent between the Javanese and the Zhoukoudian populations of H. erectus. That is, the average capacity of the Zhoukoudian fossils exceeds that of the Javanese by about 160 cubic cm. There is, however, an earlier, anomalous cranium from Gongwangling, China, that is approximately contemporary with some Java fossils. It shares with the Javanese group a smaller cranial capacity (780 cubic cm). Theoretically, the difference in brain size between the two groups of Asian fossils may be the consequence of further evolution in later populations of H. erectus. Alternatively, it may simply be interpreted as representing the variation expected between sexes or between two separate populations or subspecies of H. erectus. Several African values are also available, and in the case of the Koobi Fora and Olduvai individuals these range from about 850 to 1,067 cubic cm.
• Besides their brain capacity, the skulls of H. erectus show a number of other distinctive features. The face, which is preserved in only a few specimens, is massively constructed, and its lower parts project forward. The bone forming the wall of the nose is thinner and more everted than in earlier Homo or Australopithecus, and the nasal bridge is relatively high and prominent. This development suggests that H. erectus was well-equipped to conserve moisture that would otherwise be lost during exhalation. Such a physiological advantage would have allowed early African H. erectus to travel for longer periods in an arid environment. The braincase is low, with thick bones and sides that taper upward. Over the eye sockets is a strongly jutting browridge (supraorbital torus). There is a flattened forehead, and the part of the cranium immediately behind the browridge is appreciably constricted from side to side. A low ridge or crest of bone extends from the frontal bone along the midline of some skulls, and there tend to be strongly developed crests in the ear region. The broad-based skull has another ridge running across it. The area where the neck muscles attach is much larger than in H. habilis or Homo sapiens. Other distinguishing features in H. erectus can be found on the underside of the skull, especially at the jaw joint. The lower jaw itself is deep and robust and lacks chin development. The teeth are on the whole larger than those of Homo sapiens.

Difference between homo habilis and homo erectus:

1. Facial feature:

Homo habilis: Protruding face with prominent cheekbones

Homo erectus : Relatively flatter face with less prominent cheekbones and large brow-ridges.

2.Teeth:

Homo habilis: larger than those of modern human and elongated in appearance.

Homo erectus: Shovel shaped smaller than those of homo habilis.

3.Size of the brain :

Homo habilis: Between 550 cm3 and 687 cm3

Homo erectus:

Between 900 cm3 and 1200 cm3 larger than homo habilis.

4. Posture:

Homo habilis: stooped over while walking .

Homo erectus: walked in an upright posture.

A. Homo habilis was similar to earlier australopithecines, but had a somewhat more modern head and a bigger brain. ... Homo erectus had a bigger brain than Homo habilis and made more advanced stone tools. Homo erectus was also the first human to leave Africa (1.8 million years ago) and control fire (1.5 million years ago). This amount shows more variations.