Cradle of Life: The Discovery of Earth's Earliest Fossils

381 Pages·1999·9.82 MB·English

by  J. William Schopf

The Discovery of Earth's
Earliest Fossils
J. WILLIAM SCHOPF
Princeton University Press, Princeton, New Jersey
NORTH CENTRAL REGIONAL LIBRARY
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Copyright © 1999 by Princeton University Press
Published by Princeton University Press, 41 William Street,
Princeton, New Jersey 08540
In the United Kingdom: Princeton University Press,
Chichester, West Sussex
All Rights Reserved
Library of Congress Cataloging-in-Publication Data
Schopf, J. William, 1941-
Cradle of life : the discovery of earth's earliest fossils /
J. William Schopf.
p. cm.
Includes bibliographical references, (p. - ) and index.
ISBN 0-691-00230-4 (cl: alk. paper)
1. Life—Origin. 2. Evolutionary paleobiology.
3. Paleontology—Precambrian. 4. Micropaleontology. I. Title.
QH325.S384 1999
576.8'3—dc21 98-42443
This book has been composed in Times Roman
The paper used in this publication meets
the minimum requirements of
ANSI/NISO Z39.48-1992 (R1997)
{Permanence of Paper)
http://pup.princeton.edu
Printed in the United States of America
1 3 5 7 9 1 0 8 6 4 2
To my teachers,
from whom I learned
and my students,
who teach me still
Contents
Prologue
Acknowledgments
Chapter 1. Darwin's Dilemma
Breakthrough to the Ancient Past
The Nature of Geologic Time
The "Schoolbook" History of Life
Darwin's Dilemma
Denouement
Chapter 2. Birth of a New Field of Science
The Floodgates Crack Open
Famous Figures Enter the Field
A Youngster Joins the Fray
The Floodgates Open Full Bore
Chapter 3. The Oldest Fossils and What They Mean
"Trust but Verify"
"Real World Problems" in the Search for Early Life
Questions and Answers about the Oldest Records of Life
The Oldest Fossils Known
Chapter 4. How Did Life Begin?
The Basics of Biology
The Universals of Life
How Did Monomers of CHON Arise on the Lifeless Earth?
Organic Monomers beyond the Earth
How Did Monomers Become Linked into Polymers?
From Monomers to Polymers toward Life
Chapter 5. Metabolic Memories of the Earliest Cells
How Did Cells Begin?
The Essentials of Life
Life's Earliest Way to Make a Living
Air and Light: A New Source of Glucose
Why Do We Breathe Oxygen ?
The Four-Stage Development of Modern Metabolism
viii CONTENTS
Chapter 6. So Far, So Fast, So Early? 164
How Old Is the Modern Ecosystem? 164
When Did Life Begin ? 166
How Did Evolution Proceed So Far, So Fast, So Early? 168
Paleobiology: Fossils, Geology, and Geochemistry 169
Isotopic Evidence of Ancient Metabolisms 173
Paleobiology: Direct Evidence of Early Evolution 181
Chapter 7. Stromatolites: Earth's First High-Rise Condos 183
Nature Is Not Compartmentalized 183
Stromatolites: Earth's First High-Rise Condos 184
Stromatolites of the Geologic Past 195
What Are Stromatolites Good For? 201
Chapter 8. Cyanobacteria: Earth's Oldest "Living Fossils" 209
Modes and Tempos in the Evolution of Life 209
The Status Quo Evolution of Cyanobacteria 215
Evolution's Most Successful Ecologic Generalists 231
Chapter 9. Cells Like Ours Arise at Last 236
Life Like Us Has Cells Like Ours 236
DNA and Development: Keys to Eukaryotic Success 237
How Old Are the Eukaryotes? 240
Eukaryotes Perfect the Art of Cloning 243
Sex: A New Lifestyle Brings Major Change 246
The Wax and Wane of Precambrian Acritarchs 252
Prelude to the Phanerozoic 259
Chapter 10. Solution to Darwin's Dilemma 264
The Adventure of Science 264
Take-Home Lessons 269
Solution to Darwin's Dilemma 269
EPILOGUE
EXTRAORDINARY CLAIMS!
EXTRAORDINARY EVIDENCE? 279
Chapter 11. Fossils, Foibles, and Frauds 281
The Goal Is to (tGet It Right" 281
"Man, a Witness of the Deluge " 282
Beringer's Lying Stones 291
Theories on the Nature of Fossils 299
Unearthing a Rosetta Stone 303
Chapter 12. The Hunt for Life on Mars 304
Hints of Ancient Martian Life? 304
CONTENTS ix
NASA Stages a Press Conference 306
Meteorites from Mars 310
Search for the Smoking Gun 313
Lessons from the Hunt 324
Glossary 327
Further Reading 349
Index of Geologic Units and Genera and Species 357
Subject Index 361
Prologue
This book chronicles an amazing breakthrough in biologic and geo-
logic science—the discovery of a vast, ancient, missing fossil record
that extends life's roots to the most remote reaches of the geologic
past. At long last, after a century of unrewarded search, the earliest
85% of the history of life on Earth has been uncovered to forever
change our understanding of how evolution works.
My own role in the hunt for the ancient life dates from my student
days in the 1960s, when active studies were nearly ready to take hold.
Apparently the first to prepare at a young age for a career in this field,
I have spent that career tracing life's earliest history and have had the
privilege and supreme pleasure of seeing this young science sprout,
grow, and blossom into a vibrant venture worldwide.
My lifelong involvement in this endeavor has led me to write parts
of this book in the first person. For a science book, this is unusual. In
the guise of objectivity, we who "do science" usually present our
views in a more distant way, often writing in the third person ("it is
reported . . . ," "the data indicate . . .") as though the claims made
were someone else's, not our own. But I am not objective about this
subject—it's my life, I care about it, and it would be false for me to
pretend otherwise. Moreover, it seems to me a lot more fun to read
about how science is actually done, and by whom and why, rather
than plow through a stuffy accounting of theories and facts. "Fun" is
the operative word here. To me, science is enormously good fun!
There's hardly anything better than learning something brand new or
having a novel idea and then following that notion and finding that it
makes sense.
So, the goal of this work is to bring to light one of the truly re-
markable breakthroughs in the annals of natural science, the discovery
xii PROLOGUE
Prologue Figure What if history began in 1963?
of a long-missing fossil record that, by revealing life's earliest history,
tells us where we fit in the pattern. And while recounting this story, I
also want to show how the science itself evolved—why it took so
long for the hidden record to emerge—and convey some flavor of my
joy in being part of the endeavor.
A Fable: What If History Began in 1963?
Think for a moment how extraordinary it is that the earliest 85% of
life's history has until now remained a mystery. What would it be like
if more than four-fifths of America's past were totally unknown?
PROLOGUE xiii
The year is 1998. The place, a dorm room at UCLA in West Los
Angeles. A second-year college student sits at his desk, strug-
gling to cram into his head pivotal facts, dates, and events for his
upcoming mid-term in American History. It's good stuff, but he's
perplexed—there's so much to learn, all the way back to 1963!
President Kennedy's assassination, then Martin Luther King, Jr.,
then the president's brother Bobby . . . sit-ins, civil rights, Viet-
nam, flower children . . . space walks, lunar landings, computers,
E-mail . . . feminists, AIDS, downfall of the "evil empire." Such
a lot to sort out!
Exhausted, he daydreams: What happened before 1963? No
one seems to know. The professor once raised the question, ex-
plaining only that "a pre-1963 historical record ought to exist—
something must have happened in earlier decades—but there are
no facts to go on. No one knows what happened, or why the
record's been wiped out. It's one of history's greatest puzzles."
As the student treks across campus to take his exam, he picks
up a copy of The Daily Bruin, the student newspaper. Embla-
zoned in type 3 inches high is the bannner headline: "ANCIENT
ARCHIVES DISCOVERED—U.S. DATES FROM 1776!" Excitedly he
pours through the article. "Researchers report that conclusive
evidence of the earliest 85% of the history of the United States of
America—from 1776 to 1963—has been discovered. Long
thought forever lost, new finds document an unknown and unim-
agined early history of the country . . . a Declaration of Inde-
pendence from British rule, a written Constitution . . . Washing-
ton, Franklin, Jefferson . . . Lincoln, the Roosevelts, a feisty
Harry Truman . . . electricity, telephones, radio, television . . .
transcontinental railroad, Model T Fords, airplanes, rocket-pow-
ered flight . . . Abolition, Prohibition, women earn the right to
vote . . . the Dust Bowl, a Great Depression, the United Nations,
the Nuclear Age. ..."
Astounding! For the first time, hard facts are known that can
tell the student how his country began, then grew and prospered
over nearly 200 years that seemed lost forever. The traditional
history, the post-1963 epoch he learned so well, is only the latest
chapter of a very much longer volume!