Postural and Locomotor Adaptations of Australopithecus Species

Abstract

This paper briefly reviews what is known about locomotor anatomy and behavior of Australopithecus. I argue that the evidence most strongly supports the hypothesis that Australopithecus species were fully upright, committed terrestrial bipeds that walked with a fundamentally human-like gait despite the fact that not all aspects of their morphology were identical to that of humans. Certainly, they retained some ape-like aspects of their morphology not seen in Homo. Whether selection was also acting to retain arboreal traits, and the extent to which they engaged in arboreal behaviors, is more difficult to test rigorously. Even if they did climb trees, it is apparent that selective pressures for doing so well were of considerably weaker than those on traveling bipedally. From what little fossil evidence is available, the various species of Australopithecus postcranial adaptations show only minor interspecific variation. Further research into determining the primitive condition on which selection acted to produce earliest hominins, plasticity of the skeleton, and on variation among Australopithecus species is needed to obtain a better understanding of the evolution of locomotor and postcranial anatomy in this genus.