
This image shows the position of the fourth metatarsal Australopithecus afarensis (AL 333-160) recovered from Hadar, Ethiopia, in a foot skeleton.
The research helps resolve a long-standing debate between paleoanthropologists who think A. afarensis walked essentially as modern humans do and those who think this species practiced a form of locomotion intermediate between the quadrupedal tree-climbing of chimpanzees and human terrestrial bipedalism. The question of whether A. afarensis had fully developed pedal, or foot, arches has been part of this debate. The fourth metatarsal described in the Science report provides strong evidence for the arches and, the authors argue, support a modern-human style of locomotion for this species. The specimen was recovered from the Hadar locality 333, popularly known as the "First Family Site," the richest source of A. afarensis fossils in eastern Africa, with more than 250 specimens, representing at least 17 individuals, so far known.
Comment: This journalistic piece is a bit sensationalized. The author of the study in question writes: