Beth Shapiro searches for old bones in remote places. On a field trip to the Klondike gold fields in Canada's Yukon Territory, the expert in ancient DNA from the University of California, Santa Cruz, worked alongside mining operators as they blasted water from frozen layers of mud. What surfaced from the 700,000 year old permafrost were mammoth, bison and horse bones.

That adventure makes its way into Shapiro's new book, How to Clone a Mammoth, in which she imagines bringing the elephant's ancient cousin back to life. But she says 'de-extinction' is a complicated process, riddled with technical, ethical and ecological challenges.

In the mid-1990s, Scottish researchers cloned a sheep. Dolly was the first mammal to be cloned from an adult cell. Her birth sparked fears and speculation about human cloning.  

But Shapiro said cloning is not even an option for the mammoth.