The origin of multicellular animals is one of those difficult and delicate biological problems that have been pondered for centuries. This book summarizes recent results in phylogenetics and developmental biology that address the evolution of key innovations in metazoans. The first section covers phylogenetic issues. Focusing on nervous system and sensory organ development, the second section addresses prominent questions concerning the developmental biology of metazoan evolution. A third section discusses the evolution of pattern and process in the incredible forms of life that we call Metazoa and covers evolution of life histories and the evolution of biogeochemical aspects of metazoans. The book has over 40 illustrations and an up-to-date bibliography of over 500 references. Each chapter concludes with a set of questions for study and discussion.-- Provided by publisher.