The Science Friday interview with ASU anthropologist Donald Johanson last week is available to download at NPR.
The promo says, "In 1974, at age 31, Donald Johanson discovered the fossil he dubbed "Lucy" — a previously unknown species of ancient hominid. Johanson talks about what the discovery meant for the human family tree and discusses his new book Lucy's Legacy: The Quest for Human Origins."
The full interview runs over 26 minutes.