From a distance, you probably would have assumed her to be human. Although she stood only about a meter tall, with long arms and a small head, she walked, if perhaps slightly inelegantly, upright on two legs, as we, alone among living mammals, do. This familiar yet strange individual is Lucy, a member of the species Australopithecus afarensis, who lived some 3.2 million years ago. She is one of the oldest creatures presumed to have strode on the evolutionary path leading to our species, Homo sapiens.