The discovery of a fossil changed our understanding of human origins. But who is Lucy? Why is she so crucial to the evolution of humanity? Lucy was discovered in 1974 by archaeologist Donald Johanson and his student Tom Gray in the Hadar valley in northern Ethiopia. While Johanson and Gray were searching for animal bones among the sand, ash, and dried mud of that parched landscape, they unexpectedly found a small fragment of a human arm bone. Johanson and Gray named this fossil "Lucy" after the Beatles' song "Lucy in the Sky with Diamonds." Perhaps the real Lucy was indeed like what the lyrics sang...