In the 150 years since Darwin, the field of evolutionary biology has left a glaring gap in understanding how animals developed their astounding variety and complexity. The standard answer has been that small genetic mutations accumulate over time to produce wondrous innovations such as eyes and wings. Drawing on cutting-edge research across the spectrum of modern biology, Marc Kirschner and John Gerhart demonstrate how this stock answer is woefully inadequate. Rather they offer an original solution to the longstanding puzzle of how small random genetic change can be converted into complex, useful innovations. In a new theory they call “facilitated variation,” Kirschner and Gerhart elevate the individual organism from a passive target of natural selection to a central player in the 3-billion-year history of evolution. In clear, accessible language, the authors invite every reader to contemplate daring new ideas about evolution. By closing the major gap in Darwin’s theory Kirschner and Gerhart also provide a timely scientific rebuttal to modern critics of evolution who champion “intelligent design.” *Starred Review* Since its publication a century and a half ago, Darwin's revolutionary theory of evolution has explained very well how natural selection winnows out the mutations most helpful in fitting a species to survive. Now two neo-Darwinian biologists have boldly extended the original paradigm by showing how the deep molecular biology of the cell actually fosters biological novelties when plants and animals need them most, not merely when random chance generates them. Surveying the latest genetic research, Kirschner and Gerhart adduce evidence that nature has preserved and compartmentalized those core innovations that maximize the adaptive flexibility of species from yeasts to humans. The dynamics of protein chemistry and the plasticity of embryonic cells combine to make creatures capable of assuming many different forms in a wide range of environments. The deepest and most stable processes in biology, thus, are those that prime species for further evolution. It is this biological priming for evolutionary change that Darwin's great rival Larmark was groping toward when he stumbled into error. And it is a theoretical realignment that acknowledges this "facilitated variation" that Darwin's disciples now need in order to fend off skeptics who have latched onto the implausibility of the old scientific orthodoxy premised on entirely random and gradual change in species. Remarkably lucid and comprehensive, this new theoretical synthesis will thus shift the grounds for debate in the controversy surrounding organic evolution. Bryce Christensen Copyright © American Library Association. All rights reserved “Kirschner and Gerhart address some of the most interesting questions in current biology with enthusiasm and intellectual boldness. A remarkable advance in understanding evolution.”—Alan H. Brush, Emeritus, University of Connecticut (Alan H. Brush) "In this terrific new book, molecular systems meet evolution. The result is a wealth of stimulating ideas set among clear explanations drawn from a revelatory decade in biology."—Andrew H. Knoll, author of Life on a Young Planet (Andrew H. Knoll) "A beautifully written account of developmental evolution, integrating molecular and morphological information to describe clearly how highly complex organisms evolve through processes that facilitate variation. A tour de force." —James W. Valentine, author of On the Origin of Phyla (James W. Valentine) “One word comes to mind when I read this book: elegant. The authors have created an elegant essay/argument/overview of the subject of evolution.”—Margaret Lowman, author of Life in the Treetops: Adventures of a Woman in Field Biology (Margaret Lowman) "'Where does all the variation come from to explain the evolution of novel traits?' This book, written in simple yet engaging prose, provides an answer with a theory of facilitated variation."—Peter Grant, Princeton University (Peter Grant) "In this thought-provoking and lucidly written book, Marc Kirschner and John Gerhart address one of the most interesting, important, and yet difficult dimensions of evolutionary science—the origins of novelty. Drawing on a vast body of biological knowledge, from ant trails to the neural wiring of mouse whiskers, the authors illustrate how organisms are equipped to adapt to different and changing circumstances. They propose that variation, the raw material of evolution, is facilitated by newly understood properties of the development and physiology of organisms. This new view suggests that there is a bias in organisms capacity to evolve and in the directions that evolution takes. The Plausibility of Life will help readers understand not just the plausibility of evolution, but its remarkable, inventive powers." —Sean Carroll, author of Endless Forms Most Beautiful: The New Science of Evo Devo (Sean Carroll) " The Pla