The Shape of Life : Genes, Development, and the Evolution of Animal Form

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Summary: Strangely Difficult, but Impressive & Rewarding
Review: It took me awhile to get through this book--I probably read it twice by the time I was finished. This was because I found myself rereading nearly every paragraph as I progressed. I still have no clue why it was such hard slogging--while Raff makes little concession to the layman, the material is pretty much similar to what one finds in the "News & Reviews" section of a Nature magazine, something I'm pretty familiar with. While he has a slight tendency to be indirect and abstract in his choice of words now and then, it is nothing glaring or overly annoying. Truth is I just don't know why I found it so difficult. But I stuck with it, and there is a good reason: Raff's remarkable detailed command of nearly every aspect of modern biology is nothing short of awesome. And it has to be, for his purpose is to weave disparate, highly technical and entrenched realms of biological study (genetics, cladistics, embryology, paleontology, molecular biology, and evolutionary theory, to name the main strains) into a unified tapestry of understanding. Raff aims at providing a launching pad for such cross-disciplinary synthesis, and I believe he more than succeeds. His inital stabs at theory in this new arena are sound, I believe--he successfully questions the primacy of heterochrony as an explanatory principle of developmental evolution, and forcefully suggests developmental modularity as a deeper source of insight. For instance, Raff identifies the phylotypic Bauplan of organisms with a period of maximum module inter-connectivity in development. He coins the term "developmental hourglass" to convey the concept--both early and late development in embryos have greater developmental flexibility (due to relatively fewer interactions between developmental modules) compared to a constraining mid-developmental "waist" where the phylotype is laid down during organogenesis.

Did you just have to read that twice to get it?

Rating:
Summary: An effort to rejoin empbryology and evolution...
Review: This book represents Rudolf Raff's latest effort to shed light on the imporance of developmental biology to the future development of evolutionary theory and research. After all, evolution and its processes are evident in genes, developmental patterns and processes, and in the form of living things (animals in the case of this book). The main strength of this book is its approach to showing how the reintegration of developmental biology and evolutionary thought can help us better understand and describe how things came to be the way they are. The main weakness of the book is the limitation of the book's content to animal forms only. I appreciated the discussions showing how developmental processes allow for higher degrees of plasticity at the earliest stages of development and in later stages, but that developmental plasticity is minimized at the phylotype -- the stage of development that defines the body plan of the organism. This is an important book for developmental biologists and evolutionary biologists alike.

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Summary: The persistence of basic animal body plans
Review: This is a compelling gateway to a new perspective on evolution from the emerging developmental perspective. As the author notes at the beginning, the basic animal body plans are half a billion years old. With that the book embarks on a fascinating exploration of the relationship of evolution to development and in the process shows how our understanding, in the age of hox genes, is undergoing rapid transformation. Very interesting work indeed.

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Summary: Evolutionary development biology of metazoa
Review: This is a solid book on evolutionary developmental biology of the metazoa, suitable for the interested general reader as well as the scientific reader. A thorough set of references are provided at the end of the book.

Rating:
Summary: A Great Introduction to the Synthesis of Development and Evo
Review: Why have no new phyla emerged since the Ordovician, even after tremendous mass extinctions such as the end Permian, or when life radiated onto land, an entirely new ecological niche? Why have metazoan "body plans" been conserved since the Cambrian, even while vast amounts of morphological change has occurred within the phyla? Do developmental constraints explain this, and if so, what types of constraints? Are the arthropods monophyletic, or not? What are the developmental bases of body-plan structure, how do developmental processes shape morphology? What do new genetic data tell us about phylogenetic relationships between phyla?

These are all questions I had formulated before reading this book. Some of these questions now have good answers, and others remain obscure. Raff does a good job summarizing what is known about these and other questions. Its now obvious that knowledge of developmental processes will answer, at least partially, some long standing evolutionary questions.

Also recommended is "Genes, Embryos, and Evolution," which covers much of the same territory, but is slight more up to date and includes some excellent color plates. As a lighter read, I would recommend Simon Conway Morris' book "The Crucible of Creation," which covers the early metazoan fossil record, and discusses some very tantalizing evidence for inter-phylum evolution from Ediacaran and early Cambrian fossils.