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 Want more? National Geographic photographer Ami Vitale has covered conflict and nature. She was with Sudan when he died and she believes that the survival of creatures like the northern white rhino is intertwined with our own. Move over, Noah. Joel Sartore is building his own ark - out of photographs. He's on a decades-long mission to take portraits of more than 15,000 endangered species before it's too late. Stuart Pimm has a lot more to say about species revival. In this editorial he makes a case against de-extinction - and explains why bringing back extinct creatures could do more harm than good. It's been a long time since Jurassic Park hit theaters. Today, our revival technology straddles the line between science fact and science fiction - but do we want to go there? Also explore: Read Kate Gammon's original reporting for InsideScience, which inspired this conversation here at Overheard HQ. Want to dive further into the debate? Hear George Church's talk - and talks by some of the greatest minds in conservation - at the TedxDeExtinction conference. The Frozen Zoo is working on a lot of exciting research that didn't make it into the episode. For example, they've already managed to turn rhino skin cells into beating heart cells. To learn more about what they're up to, check out the San Diego Zoo's Institute for Conservation Research for yourself. Some of the most promising applications for the Frozen Zoo come from new technology that lets us turn one kind of cell into any other kind of cell. Read more about the first mouse that was created from skin cells. If you like what you hear and want to support more content like this, please consider a National Geographic subscription. Go to natgeo.com/exploremore to subscribe today.  Learn more about your ad choices. Visit podcastchoices.com/adchoices