A rare 4.4-million-year-old skeleton has drawn back the curtain of time to reveal the surprising body plan and ecology of our earliest ancestors.
Only a handful of individual fossils have become known as central characters in the story of human evolution. They include the first ancient human skeleton ever found, a Neandertal from Germany's Neander Valley; the Taung child from South Africa, which in 1924 showed for the first time that human ancestors lived in Africa; and the famous Lucy, whose partial skeleton further revealed a key stage in our evolution. In 2009, this small cast got a new member: Ardi, now the oldest known skeleton of a putative human ancestor, found in the Afar Depression of Ethiopia with parts of at least 35 other individuals of her species.
Ever since Lucy was discovered in 1974, researchers wondered what her own ancestors looked like and where and how they might have lived. Lucy was a primitive hominin, with a brain roughly the size of a chimpanzee's, but at 3.2 million years old, she already walked upright like we do. Even the earliest members of her species, Australopithecus afarensis, lived millions of years after the last common ancestor we shared with chimpanzees. The first act of the human story was still missing.
Original Article (free registration required): Ardipithecus ramidus -- Gibbons 326 (5960): 1598 -- Science
