HOW DID THE AUSTRALOPITHECINES WALK - A BIOMECHANICAL STUDY OF THE HIP AND THIGH OF AUSTRALOPITHECUS-AFARENSIS

Some biomechanical characteristics of the pelvis and lower limb of Australopithecus afarensis (AL, 288-1) are compared with those of modern humans, in an attempt to define the pattern of australopithecine bipedal locomotion. The reconstruction of the pelvic and femoral morphology of AL 288-1 (Schmid, 1983) is used as a basic skeletal frame to infer (1) the loading constraints acting on the supporting hip; and (2) the action of some of the main muscles of the lower limb. The analysis reconstructs the placements of the australopithecine gluteal musculature, in the pattern of African pongids and of Homo . Only the reconstruction of the gluteal musculature on the basis of the pongid pattern is consistent with the bony, structure of the fossil and would have permitted effective movements of bipedalism. Moreover, the results clearly indicate that australopithecine bipedalism differs from that of humans. (1) The extended lower limb of australopithecines would have lacked stabilization during walking; and (2) the lower limb would have shown a greater freedom for motion, which can be interpreted as the retention of a partly arboreal behavior.