Gerhard Schlosser is a scientific assistant at the Brain Research Institute, University of Bremen. He is interested in the evolution of development with a main research focus on neural development in vertebrates. Gunter P. Wagner is the Alison Richard Professor of Ecology and Evolutionary Biology at Yale University and recipient of a MacArthur Award. His interests are the theory of complex adaptations and the development and evolution of morphological characters. He most recently edited the book "The Character Concept in Evolutionary Biology.""