[The Conversation Africa] In 1974, on a survey in Hadar in the remote badlands of Ethiopia, U.S. paleoanthropologist Donald Johanson and graduate student Tom Gray found a piece of an elbow joint jutting from the dirt in a gully. It proved to be the first of 47 bones of a single individual - an early human ancestor whom Johanson nicknamed "Lucy." Her discovery would overturn what scientists thought they knew about the evolution of our own lineage.