This book, by a practicing and successful scientist, explores why questions arise in science and looks at how questions are tackled, what constitutes a valid answer, and why. The author does not bog down the reader in technical details or lists of facts to memorize. Instead, he places the questions in their historical and cultural context, ranging from the earliest intimations that the earth had a long history to current controversies, even describing the origins, challenges, and promises of modern molecular biology. Addressing issues as complex as radiocarbon dating and how we know that DNA is a double helix, he uses examples, illustrations, and descriptions that all students should be able to grasp ("Were there kangaroos in Noah's Ark?"; "Molecular Biology Ain't Rocket Science"). He gives the reader a sense of why a scientist feels always "like the child called to the stage to watch the magician do his trick". The author's thesis is that scientific logic is an extension of the common human logic used by everyone on a daily basis, and that it can and should be understood by everyone. Scientists have great passion. What could be more exhilarating than to go to work every day feeling as if you were once again a nine-year-old called up to he stage to help the magician with his trick? To be a researcher is to always be in the position of having the chance to see how the trick works. No wonder that many researchers feel that each new day is the most exciting day to be a scientist. It therefore is not surprising that scientists have such trouble communicating with non-scientists. It is difficult for the scientist to understand a life not focused on the desire to understand. But the differences are not that. Everyone wants to understand; that is one of the factors that make us human. The difference is more that scientists limit their definition of comprehension to specific rules of logic and evidence. These rules apply and are used in everyday life, but often with less rigor or restrictions on evidence. Preface ix PART 1 HOW SCIENCE WORKS 1 1 Science is an ELF 3 PART 2 ORIGIN OF THE THEORY OF EVOLUTION: TIME AND CHANGE 19 2 The Origin of the Earth and of Species of Animals and Plants as Seen Before the Enlightenment 21 3 The Seashells on the Mountaintop 35 4 Were Kangaroos on Noah's Ark? 45 5 Aristotle's and Linnaeus' Classifications of Living Creatures 55 6 Darwin's World Species, Varieties, and the Age of the Earth. Evidences of Glaciation 69 7 The Voyage of the Beagle 81 8 Is the Earth Old Enough for Evolution? 95 PART 3 ORIGIN OF THE THEORY OF EVOLUTION: SOCIAL ASPECTS 111 9 Evaluating Data 113 10 The Industrial Revolution, Population Potential, Malthus, Social Pressure, and Competition 149 11 Natural Selection: The Second Half of Darwin's Hypothesis 157 12 Darwin's Hypothesis 167 13 The Crisis in Evolution 175 PART 4 THE MOLECULAR BASIS OF EVOLUTIONARY THEORY 189 14 The Chemical Basis of Evolution 191 15 The Stuff of Inheritance: DNA, RNA, and Mutations 221 16 The Genetic Code 227 PART 5 THE HISTORY OF THE EARTH AND THE ORIGIN OF LIFE 243 17 The Story of our Planet 245 18 The Appearance of Oxygen 257 19 The Conquest of Land Every Criterion for the Classification of the Major Groups of Animals and Plants Refers to Adaptations for Life on Land 271 20 The Great Ages of our Planet 279 21 Return to Water and to Land 295 22 Evidence for Extinctions Why Do We Get Them? 303 23 The Violence of the Earth: Rainshadows and Volcanoes 319 PART 6 THE ORIGIN OF SPECIES 333 24 Competition Among Species 335 25 Sexual Selection 341 26 Coevolution 351 27 The Importance of Disease 359 28 The Aids Murder Mystery What Constitutes Proof? 369 PART 7 THE EVOLUTION OF HUMANS 379 29 The Evolution of Humans 381 30 When Did Humans Acquire a Soul? 403 31 The Impact of Evolutionary Theory: The Eugenics Society and the I.Q. Test 409 32 Evaluating Population Measurements: Bell Curves, Statistics, and Probability 425 33 Conclusions Where Do We Go from Here? 433 Index 437