Dedicated to the teachers who celebrate the ongoing adventure of science especially those who lead their students into our deep and ever growing understanding of evolution Acknowledgments Special thanks to the John Simon Guggenheim Memorial Foundation which in 2006 honored me with a fellowship to write about evolution for children I also thank Kent Brown Jr. for his call in January 2009 with the happy news of a Boyds Mills Press contract for this book the design staff especially Robbin Gourley and Carla Weise for their excellent work and editor Andy Boyles for his patience wisdom and wit as we dealt with every tiny detail and nuance of words photographs and illustrations I am deeply grateful to Dr. Jerry A. Coyne Department of Ecology and Evolution University of Chicago for his careful reading of this book's manuscript His thoroughness and detailed comments added significantly to its accuracy Any errors that remain are mine Finally thanks to my wife Susan for her support and generosity and her continued tolerance of a writer's life and to my staff the cats especially chief of staff Sabrina for her grace and beauty and for allowing me almost half of the seat of my office chair 5
Evolution Variation 7 Acknowledgments Foreword Imagine 1 2 Evidence from the Earth 12 3 How Fossils Form 16 4 Layers of Rock Layers of Past Life 19 5 The Adventures and Discoveries of Charles Darwin 23 6 28 7 32 8 Nature's Bounty 35 36 38 9 Competition 10 Natural Selection 11 After Darwin 12 Telling Time 41 43 13 Genetics 46 14 More and More Fossils 15 Missing Links Found 16 Moving Continents 17 On Faraway Islands 18 Coevolution 19 Origin of Species 20 Evolution Going On Right Now Afterword Glossary Sources Periodicals 5 9 10 Image Credits Index 52 56 63 70 74 80 84 92 94 99 100 101 102 Contents