NOVA scienceNOW: Earthquakes in the Midwest/Sleep/Sang-Mook Lee/First Primates

A look at how and why earthquakes can happen in Midwestern states; what role does sleep play in memories and the learning process; Jonathon Block, a paleontologist searches for the pre-primate missing link; and a profile of South Korean geophysicist Sang-Mook Lee, who is paralyzed from the neck down.