Homology is the central concept for all biology. This fine book brings together a selection of outstanding comparative biologists, all of whom have struggled to formulate a philosophical foundation for homology that has sufficient generality that it can serve all of biology. —Science The application of homology varies depending on the data being examined. This volume represents a state-of-the-art treatment of the different applications of this unifying concept. Chapters deal with homology on all levels, from molecules to behavior, and are authored by leading contributors to systematics, natural history, and evolutionary, developmental, and comparative biology. This paperback reprint of the original hardbound edition continues to commemorate the 150th anniversary of Sir Richard Owen's seminal paper distinguishing homology from analogy.