At the online companion Web site of "Evolution," the seven-episode series on PBS, piece together clues to how one of our early ancestors looked as you examine images from four significant fossil finds of Australopithecus afarensis.

Describes Homo habilis and Homo erectus, two early ancestors of humans. Discusses how they were discovered, their characteristics, and what we know about them, with the information clearly laid out in a chart along with some comparative...