Fossil discoveries challenge Lucy's place as 'mother of us all'

News from Science says Don Johanson and student Tom Gray found Lucy, a 40%-complete skeleton, in 1974. Some once thought her species, Australopithecus afarensis, lived close to the split between human and chimpanzee ancestors. Discoveries of older and similarly aged hominins over the following 50 years have pushed that split millions of years further back, challenging Lucy's place as 'mother of us all.'