| Acknowledgments | x |
| Introduction | 1 |
| Part 1. Intimations: Many Questions but No Good Answers | |
| Chapter 1 | |
| Six Who Helped Lay the Groundwork | 7 |
| Carolus Linnaeus: "I will sort and name many things." | 10 |
| George Louis Leclerc, Comte de Buffon: "I will describe and explain everything." | 14 |
| James Hutton: "The world is older than you think." | 20 |
| Jean Baptiste Lamarck: "Species change.They do it by striving." | 22 |
| Georges Cuvier: "Fossils are real." | 26 |
| Thomas Malthus: "Life is a struggle. Only the fittest survive." | 30 |
| Part 11. A Theory at Last: Charles Darwin and the Origin of Species | |
| Chapter 2 | |
| The Voyage of the Beagle. First Suspicions about Change. Years of Lonely Labor. | 37 |
| Chapter 3 | |
| A Shock from the Spice Islands. The Shocker: Alfred Russel Wallace. | 70 |
| Chapter 4 | |
| The Origin Is Published. The Reaction. | 84 |
| Part 111. Two Problems That Darwin Could Not Solve | |
| Chapter 5 | |
| Gregor Mendel. The Problem of Blending Explained: Traits Endure. | 105 |
| Chapter 6 | |
| Hugo de Vries. The Source of Variation Found: Mutations Occur. Mendel Is Vindicated. | 123 |
| Part IV. Inside the Cell: Chromosomes and Genes | |
| Chapter 7. | |
| The Role of the Chromosome | 135 |
| August Weismann: "Your chromosomes determine what you are." | 138 |
| Theodor Boveri: "Yes, and you need them all." | 140 |
| The Bicycle Factory: Designers and Workers. | 143 |
| Chapter 8 | |
| The Fly Room | 146 |
| T. H. Morgan (early): "Forget genes; they don't exist." | 146 |
| T. H. Morgan (later): "Sorry; they do." | 151 |
| Alfred Sturtevant: Crossing Over Discovered. | 162 |
| Hermann J. Muller: The Source of Mutations Revealed. Darwin in Eclipse. | 171 |
| Darwin Rehabilitated: The New Evolutionary Synthesis. | 179 |
| Part V. Inside the Chromosome: DNA and RNA | |
| Chapter 9 | |
| Friedrich Miescher: What Are Chromosomes Made of? Answer: DNA. | 185 |
| Chapter 10 | |
| George Beadle and Edward L. Tatum: What Does DNA Do? It Hands Out Instructions and Thus Changes Things. | 193 |
| Chapter 11 | |
| Oswald Avery: Is That Really True? Yes; DNA Is the Transforming Agent. | 205 |
| Chapter 12 | |
| James Watson and Francis Crick: How Is DNA Put Together? | 215 |
| The First Model a Disaster. | 220 |
| The Second Model a Triumph. The Double Helix. | 226 |
| Chapter 13 | |
| Questions for Crick: What Does the Code Say? How Is It Read? Is RNA Involved? | 235 |
| Chapter 14 | |
| The Dual Nature of DNA | 251 |
| Matthew Meselson and Franklin Stahl: Autocatalysis--DNA Makes Itself. | 251 |
| Arthur Kornberg: Heterocatalysis--a Relationship Between DNA and Proteins Is Established. | 255 |
| Marshall Nirenberg and Johann Matthaei: The DNA Code Is Cracked. | 258 |
| Chapter 15 | |
| The Triplet Code and the Ribosome. Crick Enunciates the Central Dogma. | 267 |
| Part Vl. The Origin of Life | |
| Chapter 16 | |
| Stanley L. Miller and Manfred Eigen: A Look from the Bottom Up. | 281 |
| Chapter 17 | |
| Carl R. Woese: A Look from the Top Down. | 296 |
| Part Vll. DNA and the Fossil Record | |
| Chapter 18 | |
| What Old Bones Have to Say about Human Evolution. What Molecules Have to Say. | 325 |
| Part Vlll. Specialization and Extinction | |
| Chapter 19 | |
| Is There Danger in Being Too Smart? | 371 |
| Bibliography | 391 |
| Illustration Credits | 395 |
| Index | 397 |