Don Johanson describes finding the knee joint in Hadar, Ethiopia, that first indicated a bipedal hominid had lived 3 million years ago. His subsequent expedition led to the discovery of Lucy, a 40 percent complete skeleton of a new species of hominid, now known as Australopithecus afarensis. The final piece of the puzzle was a skull from the same site, which clearly demonstrated that Lucy's kind were small-brained, although they walked upright. From NOVA: In Search of Human Origins.
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