Question

A portion of an ancient skeleton has been uncovered in Asia. Since the skull is missing, the discoverers can not determine whether the skeleton is from a human or some type of ape. The only portions that the excavators have been able to find are the pelvis and one complete leg. What should they look for?

Answer 1

Ans) The human pelvis is totally different. It would be obvious by that alone.
- The human has apelike features of the head and arms, but the lower limbs of Australopithecus afarensis were non-apelike, and are virtually indistinguishable from those of humans.

- In humans, the heel bones have an enlarged pad composed of spongy bone which absorbs the shock generated by our bipedal mode of walking. Apes, which do not walk on two legs but instead 'knuckle-walk", do not have such a bony pad.

- Ape, Lucy's femur was slightly longer, proportionately, than in humans.

- In humans, the neck of the femur, where it fits into the hip socket, has a thick spongy center as a cushion to absorb the impact of walking, and has a thicker layer of harder bone at the top portion of the joint to withstand the stress. In apes, however, the arrangement is entirely different; the neck of the femur is almost completely solid, with just a small central core of spongy bone. Ape femurs also have a large keel running along the top of the neck where it joins the hip socket.

- The Australopithecus afarensis femur is identical to the human arrangement.
- In apes, the knee joint forms a straight vertical line from the thigh bone through the knee and on into the shin bones. In humans, with their upright mode of locomotion, the center of gravity must be shifted inside the pelvic girdle. Thus, the thigh bone in a human approaches the knee joint from an outside angle, and the limbs do not have the straight-line configuration seen in the apes.

- Similarly, the Lucy type of Australopithecine demonstrates a human like type of structure rather than an apelike one. A. afarensis limbs meet at a sharp angle between the lower end of the femur and the knee joint, like in humans.
- It is in the pelvic girdle, there is humanlike characteristics of Australopithecus afarensis which are most readily apparent.

- In humans, the pelvic girdle is wide and flattened into a shallow dish shape to hold the weight of the upper body during walking. In apes, the knuckles bear most of the weight during walking. In Lucy, the pelvis was almost identical to that of a human.

- The sacrum in apes is narrow. In humans, the sacrum must be wide enough to set the hip joints apart for walking. The Australopithecus afarensis sacrum was not only wide like a humans rather than narrow like an ape's, but was actually proportionately wider than that of modern humans.

- The Lucy's sacrum was wide, since this would in turn narrow the opening of the birth canal. In humans, the birth canal is wide as possible to allow the relatively large-headed human baby to pass through, but in A. afarensis, with its smaller head and brain, this was not a problem. The Australopithecus afarensis pelvic girdle, therefore, was actually better suited for bipedal walking than is our own. "

So having this comparison of human vs Apes, we get to know the typical similar & different characteristics of the skeleton.