Australopithecines, dinosaurs, trilobites--such fossils conjure up images of lost worlds filled with vanished organisms. But in the full history of life, ancient animals, even the trilobites, form only the half-billion-year tip of a nearly four-billion-year iceberg. Andrew Knoll explores the deep history of life from its origins on a young planet to the incredible Cambrian explosion, presenting a compelling new explanation for the emergence of biological novelty.

The very latest discoveries in paleontology--many of them made by the author and his students--are integrated with emerging insights from molecular biology and earth system science to forge a broad understanding of how the biological diversity that surrounds us came to be. Moving from Siberia to Namibia to the Bahamas, Knoll shows how life and environment have evolved together through Earth's history. Innovations in biology have helped shape our air and oceans, and, just as surely, environmental change has influenced the course of evolution, repeatedly closing off opportunities for some species while opening avenues for others.

Readers go into the field to confront fossils, enter the lab to discern the inner workings of cells, and alight on Mars to ask how our terrestrial experience can guide exploration for life beyond our planet. Along the way, Knoll brings us up-to-date on some of science's hottest questions, from the oldest fossils and claims of life beyond the Earth to the hypothesis of global glaciation and Knoll's own unifying concept of ''permissive ecology.''

In laying bare Earth's deepest biological roots, Life on a Young Planet helps us understand our own place in the universe--and our responsibility as stewards of a world four billion years in the making.

In this wonderful book . . . Knoll's extensive field experience and eagerness to share data and ideas with colleagues enable him to reconstruct responsibly the broad evolutionary scenario yet to remain close to the evidence.

A balanced, excellent account of current theories and discussions of the origin and early evolution of life. . . . Knoll is able to convey difficult scientific issues with a minimum of jargon, using a brisk and witty prose. . . He is a gifted storyteller with a knack for choosing the right anecdote. . . . A browse through Knoll's book will enlighten both the cognoscenti and those unfamiliar with the complexities of reading a fossil record. . . . Knoll manages to present a multidisciplinary field in an interdisciplinary volume.

?? is a detective story to match the best crime fiction?. The Guardian

In a book so well written that nonspecialists and specialists alike will find much to savor, [Knoll] captures both the excitement of scientific discovery and the intricacies of scientific interpretation. . . . Readers interested in substance will certainly not be disappointed.

The author weaves a beautifully written, fascinating story of life's origin and development based on his extensive field studies and research in the most remote corners of the globe. . . . This volume . . . is a most valuable asset that should be read by scientists active in the field, by teachers and students who are interested in the most recent thoughts on the subject, and, in fact, by anyone who is interested in how life might have originated and evolved on this planet or on other similar planets in our Universe.

Knoll is well placed to tell this amazing story, and he does so with verve.

[Knoll's] words have a poetic flavor and his deep interest in the study of life on earth flows out of them, carrying readers along whole maintaining a rigorous discourse. Knoll's book will appeal to anyone interested in the evolution of life on Earth.

A detective story to match the best crime fiction. It is told with verve.

A fascinating book. . . . The catastrophic surface narrative of this impressive and intriguing book would surely have pleased Stephen Jay Gould; but I think its deterministic subtext would have pleased Charles Darwin still more.

Knoll explores the deep history of life from its origins on a young planet to the incredible Cambrian explosion, with the very latest discoveries in paleontology integrated with emerging insights from molecular biology and earth system science. 100 illustrations.

Acknowledgments ix

Prologue 1

Chapter 1. In the Beginning? 6

Chapter 2. The Tree of Life 16

Chapter 3. Life's Signature in Ancient Rocks 32

Chapter 4. The Earliest Glimmers of Life 50

Chapter 5. The Emergence of Life 72

Chapter 6. The Oxygen Revolution 89

Chapter 7. The Cyanobacteria, Life's Microbial Heroes 108

Chapter 8. The Origins of Eukaryotic Cells 122

Chapter 9. Fossils of Early Eukaryotes 139

Chapter 10. Animals Take the Stage 161

Chapter 11. Cambrian Redux 179

Chapter 12. Dynamic Earth, Permissive Ecology 206

Chapter 13. Paleontology ad Astra 225

Epilogue 243

Further Reading 247

Index 269