Striding bipedalism is a mode of locomotion that defines our lineage. Bipedality freed the hands, arms and shoulders from the mechanical constraints of locomotion, an evolutionary innovation that has had an obvious impact on our species' fitness. As I will discuss in this dissertation, the shoulder blade (scapula) is shaped to optimize use of the upper limb in certain positions. Our closest living relatives (chimpanzees and gorillas) possess adaptations that likely increase efficiency in overhead use of the arms, as in forearm suspension or vertical climbing. The modern human shoulder, on the other hand, lacks such adaptations. This difference may reflect an evolutionary change in shape that occurred as our ancestors transitioned to a terrestrial way of life and became increasingly dexterous, eventually losing ancestral adaptations. On the other hand, recent discoveries suggest our lineage may have never possessed adaptations to suspension. Fossils from the shoulder of our early human ancestors are scarce. A recently discovered partial skeleton from Woranso-Mille (Afar Depression, Ethiopia), KSD-VP-1/1, preserves the oldest and most complete scapula of an adult Australopithecus afarensis individual. The intended contribution of this dissertation is to provide a comparative description of the new scapula (KSD-VP-1/1g) and to detail its implications for our understanding of anatomy and adaptation in the Australopithecus shoulder, and the evolutionary history of the modern human shoulder more generally.