Forty years ago, President Nixon signed the National Cancer Act, beginning the War on Cancer. Harold Varmus, director of the National Cancer Institute, discusses four decades of scientific progress in preventing, detecting and treating cancer--and the mysteries that still remain.

By tracking the blinking light of distant stars, NASA's Kepler space telescope has identified the first Earth-sized exoplanets, and another which orbits its star in the "Goldilocks zone," where liquid water--and possibly life--could exist. Principal investigator William Borucki talks about the newly discovered worlds.

When a Mumbai hotel was besieged by terrorists in 2008, something extraordinary happened: Workers didn't flee. They stayed behind to help save guests at the risk of their own lives. What could possibly explain it? A new study attempts to answer that question.

The Obama administration is trudging ahead with policies designed to protect the integrity of scientific research. But critics of the process say the policies that have been released so far don't do enough to prevent political manipulation of science.

Birds and wasps do it. So do octopuses, otters, polar bears and dolphins. A surprising number of animals use tools, and scientists say there are some widespread misconceptions. Among them: Using tools isn't a sign of intelligence, and animals don't need fingers to be crafty with tools.