"Five fossil human skulls show how the shape of the face and braincase of early humans changed over the past 2.5 million years. (from left to right: Australopithecus africanus, 2.5 million years old; Homo rudolfensis, 1.9 million years old; Homo erectus, ~ 1 million years old; Homo heidelbergensis, ~350,000 years old; Homo sapiens, ~ 4,800 years old)"