Pbs News Hour Extra: Scientists Discover Oldest Human Ancestor

Scientists have recently published their research into fossil bones from Ethiopia that they say came from an ancestor common to both humans and chimpanzees. They have named the ancestor Ardipithecus ramidus. In the articles and video, scientists talk about this discovery and the impact it is having on our beliefs about evolution. Lesson plans accompany the articles. (October 2, 2009)