Thomas Prang

Preliminary abstract: The purpose of this investigation is to understand the origin and evolution of hominin bipedalism by evaluating competing hypotheses about the nature of arboreal and terrestrial locomotion of early hominins (including Ardipithecus ramidus, BRT-VP-2/73, Australopithecus afarensis), and the Homo-Pan last common ancestor (LCA) on the basis of foot morphology Specifically, this study has three major objectives: (1) To evaluate morphological correlates of locomotion among anthropoid primates to better understand locomotion in early hominins (Ar. ramidus, BRT-VP-2/73, Au. afarensis); (2) To reconstruct the evolution of the foot in the Hominoidea and the morphology of the Pan-Homo last common ancestor (LCA) using advanced phylogenetic comparative and evolutionary modeling methods; and (3) To evaluate the hypothesis that multiple kinematically distinct forms of bipedalism existed in the Pliocene by testing whether Australopithecus afarensis possessed a more terrestrially adapted foot (Latimer and Lovejoy, 1990) than the taxon represented by the BRT-VP-2/73 partial foot from Woranso-Mille, Ethiopia (Haile-Selassie et al., 2012). The study of the functional morphology and evolution of the hallux and forefoot will provide new insight into form-function relationships in the foot of living anthropoid primates, which will help to understand how the earliest hominins (e.g., Ar. ramidus, BRT-VP-2/73, Au. afarensis) used their feet during arboreality and terrestriality, and the way in which the hominin foot evolved. The three major components of this study are essential steps in making inferences about the posture and locomotion of the hominin-panin last common ancestor, in which the evolution of bipedalism and the origin of the human lineage is rooted.