Although Darwinian evolution is the leading theory for how organisms change with time, it is not without mystery. One of these mysteries is how natural selection creates new innovations. Natural selection is supposed to preserve survival traits, but how can this mindless process fabricate new traits that adapt to an ever-changing environment? Unless this question is answered, the theory of evolution remains incomplete, if not wrong. If reproduction, as the story goes, churns out random mutations, and there is only one molecular arrangement that will solve a problem presented by the environment, there would not have been enough time since the Big Bang for the solution to appear. This week’s guest, Professor Andreas Wagner, of the University of Zurich in Switzerland, has written a new book, Arrival of the Fittest: Solving Evolution’s Greatest Puzzle, that takes this problem head-on: he argues that the library of nature has not one, but millions, of possible paths to a trait that solves a survivability challenge. But then the questions becomes, where did this library of multiple solutions come from? Listen in as Philip and Professor Wagner break some new ground in addressing this mystery of evolution.