Paleoanthropologist Donald Johanson On What Lucy Says About Us

She certainly shook up our family tree that day in 1974. The human family tree that is.

Thursday in an encore broadcast of Up to Date Steve Kraske welcomes paleoanthropologist Donald Johanson who discovered the 3.2 million-year-old Australopithecus afarensis. Too hard to pronounce? Don't worry, you can call her Lucy. And while a certain redhead might have her beat as the most famous to hold the moniker, she certainly holds the title in the world of fossils.

This hour we ask Johanson about that day in Ethiopia when he unearthed the bones. Plus, we talk about how he and his colleagues have uncovered specimens spanning 400,000 years and what it tells us about our evolution. And what do we still not know? It's been 38 years since his infamous find, but he continues to seek out answers to that question.