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Sleep: Why do we need sleep? Exploration of sleep in the role of all animals to strengthen memories (originally aired July 10, 2007)
First Primates: Our most distant primate ancestors, which took the stage shortly after the dinosurs were gone, were tree dwellers the size of mice (originally aired July 9, 2008)
Earthquakes: 3 massive earthquakes struck American Midwest in early 19th century. Will it happen again?
Profile: Sang-Mook Lee: A South Korean professor of geophysics, paralyzed from the neck down from an accident, defies disabled stereotypes.moreless