My ideas for this book have been evolving over the last several years as I have been working in the animal modeling area and have seen it change rather dramatically. There have been tremendous advances, both in methodology and in conceptualization, yet the literature is scattered in journals encompassing many disciplines. In particular, there have been only very limited attempts to write about the philosophical, conceptual, and controversial issues in this field; to pull together diverse findings; and to provide some general perspective on its future. As will probably be apparent, I am a...