Talk of genetic “programs” is common both in popular presentations of biology, and in biology itself. Often, the idea is just a vivid (but perhaps misleading) way of drawing attention to the orderly, well-controlled and highly structured character of development. In its overall results, development is astonishingly stable and predictable, despite the extraordinary complexity of intracellular and intercellular interactions, and despite the fact that the physical context in which development takes place can never be precisely controlled. So when biologists speak, for example, of “programmed cell death”, they could just as well say that in an important class of cases, cell death is predictable, organised, and adaptive.