The Frozen Zoo

Right now, one million animal and plant species are threatened with extinction. Conservation scientists are doing whatever they can to save them, or at least of piece of them. For the last 45 years, a team of researchers at the San Diego Zoo has been freezing the cells of endangered animals. With these time capsules of DNA, researchers continue to study endangered animals, and hope to maybe even bring some back from the brink of extinction. For more information on this episode, visit nationalgeographic.com/overheard