Why do the best-known examples of evolutionary change involve the alteration of one kind of animal into another very similar one, like the evolution of a bigger beak in a bird? Wouldn't it be much more interesting to understand how beaks originated? Most people would agree, but until recently we didn't know much about such origins. That is now changing, with the growth of the interdisciplinary field evo-devo, which deals with the relationship between how embryos develop in the short term and how they (and the adults they grow into) evolve in the long term. One of the key questions is: can the...