Lucy's lower limbs: long enough for Lucy to be fully bipedal?

Abstract

The recent attempt to show that the Hadar australopithecine female 'Lucy' (AL 288-1) had hindlimbs too short to allow a modern pattern of striding bipedal gait1 has important implications for understanding the origin of bipedalism, if not for the more general problem of hominid origins. Combined with previous claims that Lucy had a forelimb unusually long in proportion 2 and ape-like in morphology3, the additional contention of a relatively short hindlimb would suggest a very different pattern of gait from the norm of today because the effectiveness of the pendulum action of the lower limb during stride is a function of the amount of mass in the limb 4, and because a short hindlimb would necessitate a short stride length1. Yet, these contentions seem contradicted by the analyses of Lucy's pelvis (and the innomminates of other australopithecines)4,5 that indicate a similar pattern of muscle use and imply a lack of significant gait differences. Are Lucy's legs too short to allow an effective stride, or is there a different solution to this contra diction? I propose here that there is. © 1983 Nature Publishing Group.