Part IV is concerned mainly to set up for further work on what should be one of the most important topics in the philosophy of biology for the next decade: the interpretation of new work on animal development. Chapter 10 is primarily historical; it concerns the long-term difficulties of integrating genetics and development and the sharp divisions that arose between those two disciplines. Chapters 11 and 12 seek to interpret recent work aimed at integrating development, evolution, and genetics of animals. This work belongs to the new interdisciplinary field of “evolutionary developmental biology,” which will be the jumping-off point for much of this work (see also Arthur 1997; Burian, et al. 2000; Gilbert 2003; Hall 1999, 2000; Hall and Olson 2003; Raff 1996, 2000). As should be clear, these chapters deal with issues that are not stably resolved; they attempt to provide an interpretative framework that will help with the ongoing struggles to resolve a large number of open questions.

Chapter 10, previously unpublished, is closely based on a talk I delivered in the fall of 1986 at the Department of History and Sociology of Science at the University of Pennsylvania. There has been a considerable amount of historical work on the conflicts between embryologists and geneticists since 1986, so the chapter is by no means groundbreaking, but the fundamental conflicts involved are still not nearly as well known as they should be.