Host Bill Nye examines ten milestones in the origin and evolution of life on earth. This program covers: Walter Alvarez's K-T asteroid theory of dinosaur extinction; the first identification of dinosaur fossils; Stanley Miller's simulation of the early atmosphere, leading to organic compound formation; Robert Ballard's discovery of hydrothermal vent ecosystems; Charles Walcott's analysis of the Burgess Shale; the Linnaean classification system; Darwin's theory of natural selection; Donald Johanson's "Lucy"; Mary Leaky's Laetoli footprints; and Michel Brunet's Toumai skull.