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Excerpt from The Evolution of Life, or Causes of Change in Animal Forms: A Study in Biology The great question of The Evolution of Life upon the earth, and the causes that have led to the successive changes in animal forms, is one that should be treated from an anatomical and a physiological point of view. Scientists have hitherto spoken of these changes that have taken place, and have concurred in the opinion that the lower forms of life have advanced in the scale of development, and in time have given rise to higher and newer forms. It is believed and generally accepted that the protoplasmic cell was the first vital organism that appeared upon the earth - that, following this in order came the protozoans, the fishes, the reptiles, the marsupials, the mammals, the higher apes, and finally man, but no attempt has ever been made, as far as I know, to explain the physiological causes of these changes in the anatomy of the animal kingdom. It is only a part of the truth to say that a reptile was evolved from a fish, a mammal from a reptile, and man from the higher apes. But this is not enough. The world is advancing to that point when it demands to know [1010 these changes took place, by what physi ological process they occurred, and what was the reason that induced them to change. It is this great point that I have endeavored to explain, - how far, and how well I have succeeded, I leave others to judge. If any thing is left unsaid or unexplained it may serve as a stimulus to future writers to finish the work I have planned out. I have written this work from a physi. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.

Rudolf Raff is recognized as a pioneer in evolutionary developmental biology. In their 1983 book, Embryos, Genes, and Evolution, Raff and co-author Thomas Kaufman proposed a synthesis of developmental and evolutionary biology. In The Shape of Life, Raff analyzes the rise of this new experimental discipline and lays out new research questions, hypotheses, and approaches to guide its development. Raff uses the evolution of animal body plans to exemplify the interplay between developmental mechanisms and evolutionary patterns. Animal body plans emerged half a billion years ago. Evolution within these body plans during this span of time has resulted in the tremendous diversity of living animal forms. Raff argues for an integrated approach to the study of the intertwined roles of development and evolution involving phylogenetic, comparative, and functional biology. This new synthesis will interest not only scientists working in these areas, but also paleontologists, zoologists, morphologists, molecular biologists, and geneticists.