Abstract: The locomotion mode of Australopithecus has long been a hot topic for palaeoanthropologists. The fossil specimen of Lucy (A1288-1) has its most long bones and pelvis preserved, so that researchers may have a detailed study on her body morphology and skeleton structure. Even based on the exact the same morphological data, there is still, oddly, a major and prolonged disagreement. Starting from Lucy' s anthropometric data and aided by the computer simulation technique, this study built a series of dynamic modes, with a combination of lower limb joint moving functions and static characteristics of Lucy. It was shown that had Lucy had walked with a bent-knee, bent-hip (BK-BH) posture, it would have been much more expensive in energy consumption than otherwise if she were walking in a fully erect manner. This suggested that Lucy may have been walking bipedally and erectly just like us today. However, further analysis indicates that the femurs of Australopithecus including Lucy' s are of stronger anti-deformation ability in both sagittal and frontal plans, agreeing the joint torque output for the BKBH model built in this study. This finding suggests a total different conclusion.

Key words: Australopithecus; Gait; Computer Simulation; Energy; Torque