Sir David Attenborough at the Beijing Museum of Natural History with fossil of Juramaia, as featured in the Smithsonian Channel series Rise of Animals: Triumph of the Vertebrates. Courtesy Smithsonian Channel hide caption

itoggle caption Courtesy Smithsonian Channel

Human evolution is an unfolding process with chapters yet to be written; no one really knows where we're going. But we can look back to earlier chapters, with ancestors like Australpithecus afarensis, including the individual we call "Lucy" (seen above), for an understanding of how evolution works and what has happened to us over time. Tim Boyle/Getty Images hide caption

itoggle caption Tim Boyle/Getty Images