May 1, 2003

Todd is joined by Gabrielle Walker to discuss the "Snowball Earth" theory. Walker tells Todd about Paul Hoffman, the scientist behind the "Snowball" theory, which is based on his findings about the earth after it froze over 700 million years ago. Walker wrote about Hoffman and his theory in "Snowball Earth: The Story of the Great Global Catastrophe That Spawned Life As We Know It."

Air Force Col. Gail Halvorsen joins Todd to discuss his career as "Candy Bomber." He tells Todd how he began dropping parachutes of candy for children in Berlin when the Soviets formed a blockade there after World War II. He has since dropped candy to many war-torn countries, and he hopes to do the same in Baghdad.

Donald Lindburg joins Todd to discuss why panda populations have decreased in natural habitats, and how researchers have discovered ways to increase the success rate of panda breeding programs. Lindburg, who is a specialist in animal behavior from the San Diego Zoo, explains what researchers are learning about how adult pandas communicate with each other using scent.