All biological organisms compete for limited resources. The successful ones reproduce, and their species survive to another generation. And when species are in direct competition, the one that wins is the one that reproduces fastest -- according to the traditional rules of population genetics. But recent research indicates that rapid reproduction may not always be the winning evolutionary ticket. When mutation rates are low, says Chris Adami of the California Institute of Technology (Caltech), the standard rule applies. But when mutation rates are high, a different principle applies, which Adami and his colleagues call "survival of the flattest." Adami hasn't...