Mass Extinction - What caused the mother of all extinctions 250 million years ago?1918 Flu - A virus that killed up to 50 million people is brought back to life to decipher its deadliness.Profile: Cynthia Breazeal - A daring engineer designs robots to communicate and interact the way people do.Papyrus - Scraps of writings from a garbage dump in ancient Egypt reveal what life was like 2,000 years ago.