The question isn't if wooly mammoths can be cloned, but when—and just as importantly, why? Having explored UFOs in The 37th Parallel, Ben Mezrich travels from Siberia to the genetic labs of Harvard University, profiling the scientists who are splicing DNA from frozen woolly mammoths into a modern elephant. Discussing the ethics of reversing extinction, Mezrich also tells the story of a millionaire planning the world's first Pleistocene Park, with ancient herbivores as a hedge against an environmental ticking time bomb within the permafrost.