Forty years ago, scientists made an incredible discovery in Ethiopia: a 40 percent complete skeleton of a previously unknown type of ancient hominid thought to be more than 3 million years old.
They called her Lucy.
Lucy's discovery shook up the scientific world, sparking a rethinking of the origins of humans.
For more on the legacy of Lucy, Alex Cohen sat down with Dr. Donald Johanson, the scientist who first discovered Lucy. He's also the director of the Institute of Human Origins at Arizona State University.
Check out some photos of Lucy at ASU libraries Flickr page here.