The book integrates our understanding of the factors and processes underlying the evolution of multicellularity by providing several complementary perspectives (both theoretical and experimental) and using examples from various lineages in which multicellularity evolved. Recent years marked an increased interest in understanding how and why these transitions occurred, and data from various fields are providing new insights into the forces driving the several independent transitions to multicellular life as well as into the genetic and molecular basis for the evolution of this phenotype. The ultimate goal of this book is to facilitate the identification of general and unifying principles and mechanisms.

Iñaki Ruiz-Trillo is an ICREA Research Professor at the Institut de Biologia Evolutiva (CSIC-UPF) in Barcelona. His educational background includes a B.S. in Biology from the University of Barcelona. He earned a Ph.D. in Biology from the University of Barcelona and completed a post-doctoral fellowship at the Dalhousie University (Canada). His current research interests include the study of the molecular mechanisms involved in the origin of multicellular animals, the analysis of genomes of different protists, the study of higher phylogenetic relationships of eukaryotes, and the understanding of the genetic repertoire of the last eukaryotic common ancestor.Aurora M. Nedelcu is a Professor in the Department of Biology at the University of New Brunswick (Fredericton, Canada). She also holds an Adjunct position in the Department of Ecology and Evolutionary Biology (EEB) at the University of Arizona (Tucson, USA) and is an External Faculty in the Center for Evolutionand Cancer at the University of California San Francisco (USA). She received a BSc in Biology from ³Babes-Bolyai² University (Cluj, Romania), and a PhD in Biology from Dalhousie University Halifax, Canada). She completed her postdoctoral training in the Organelle Genome Mega sequencing Lab at the Universite de Montreal  and in the EEB Department at the University of Arizona. Her current research interests include understanding the principles and mechanisms involved in the evolution of complexity, multicellularity, cell differentiation, altruism, programmed cell death, and cancer.

Part 1: Multicellularity in the tree of life.- Part 2. Model-systems.- Part 3: Theoretical approaches.- Part 4: Genomics insights.- Part 5: Molecular mechanisms.