THE recipe for making any creature is written in its DNA. So last November, when geneticists published the near-complete DNA sequence of the long-extinct woolly mammoth, there was much speculation about whether we could bring this behemoth back to life. Creating a living, breathing creature from a genome sequence that exists only in a computer's memory is not possible right now. But someone someday is sure to try it, predicts Stephan Schuster, a molecular biologist at Pennsylvania State University, University Park, and a driving force behind the mammoth genome project. So besides the mammoth, what other extinct beasts might we...