Walking The Line: Examining an Illustration of A.L. 288-1 for Anatomical Accuracy and Its Implications for Studying Australopithecine Locomotion

Abstract

After over 45 years, since Dr. Donald Johanson’s famed discovery of “Lucy” (A.L. 288-1), a debate in the scientific community still endures over the nature of her bipedal gait. Did Australopithecus afarensis walk upright more as a great ape, with significant hip and knee flexion (the Bent-Hip Bent-Knee [BHBK] walking hypothesis), or was her gait closer to a modern human’s? At the heart of this debate is a single pen-and-ink line drawing, first published in an article by Drs. J. Stern and R. Susman on australopithecine locomotion (Stern and Susman, 1983). Despite the decades of arguments that have followed, this lone two-dimensional fossil reconstruction has never been tested. This project compares the with a contemporary 3D model of A.L. 288-1, and deciding if the Stern and Susman (1983) figure, which has been crucial to BHBK proponents, is indeed anatomically accurate. To test the drawing’s accuracy, casts of A.L. 288-1’s innominate and sacrum were scanned using high-resolution computed tomography (UHR CT). This produced a 3D mesh which was compared to the original illustration. In the end, it was not possible to match the drawing to the model. Though it demonstrates nothing about australopithecine gait in itself, it undermines the BHBK hypothesis which is derived from the drawing, since it contains flawed anatomy. The flaws are likely due to the source material provided to the artist, demonstrating the importance of the collaboration between scientists and illustrators, and their ability to understand one another.

Kurt Esenwein Chairpersons of the Advisory Committee Adam D. Sylvester, PhD, Associate Professor, Center for Functional Anatomy and Evolution Timothy H. Phelps, MS, FAMI, Professor (Faculty Advisor), Art as Applied to Medicine tphelps1@jhmi.edu