More on the White Space in Evolutionary Thinking: A Critic Responds to How to Build a Worm

Getting to adulthood isn't so simple. An egg does not morph into a chick in a single leap, or a chick into a hen. Rather, the fertilized egg must undergo a series of cell divisions accompanied by complex molecular interactions that bit by bit restrict what each cell lineage can do, and these lineages work together to construct the final integrated functional form. For a hen's egg the result is a hen; in the case of the butterfly egg it's a butterfly. And for C. elegans it's a microscopic wor...