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DORION SAGAN
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MICROCOSMOS FOUR BILLION YEARS OF MICROBIAL EVOLUTION
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Foreword by Lewis Thomas
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Microcosmos
MICROCOSMOS Four Billion Years of Evolution from Our Microbial Ancestors
Lynn Margulis and Dorion Sagan Foreword by Lewis Thomas
UNIVERSITY OF CALIFORNIA
Berkeley
Los
Angeles
PRESS
London
University of Califomia Press Berkeley and Los Angeles, Califomia University of California Press, Ltd. London, England First Califomia Paperback Printing 1997
Copyright
@ 1,986by
Lynn Margulis and Dorion Sagan
All rights reserved including the right of reproduction in whole or in part in any form Manufactured in the United States of America
10987654321 Library of Congress Cataloging-in-Publication data Margulis, Lynn, 1938Microcosmos : four billion years of evolution from our microbial ancestors / LyrnMargulis and Dorion Sagan : foreword by Dr' Lewis Thomas.
P.cm.
Originally published : New York : Summit Books, O 1985. With rev' pref. Includes bibliographical references and index. ISBN G'520-2106t1-5 (pbk. : alk. paper) 1..
Evolution (Biology).
Dorion,
2.
1959- . II. Title.
QH371.M28
Microorganisms-Evolution. I. Sagan,
1997
576.8-DC27
96-49685
CIP The paper used in this publication meets the minimum requirements of American National Standard for lnformation Sciences-Permanence of Paper for Printed Library Materials, ANSI239.4&1984. e)
To the memory of Moruis Alexnnder (D ecember 24, 1.909 -N oaember 3, L994),
father and granilfatlur,
andhis loae of life
CONTENTS
F oreroord by
kutis
Thomas (19 8 5)
9
Preface
13
Acknowledgments
25
lntro duction: The Mcrocosm
27
L. 2. 3. 4. 5. 6. 7. 8. 9.
Out of the Cosmos The Animation of Matter The Language of Nature Entering the Microcosm
39
47 59 69
Sex and Worldwide Genetic Exchange
85
The Oxygen Holocaust
99
New Cells LivingTogether The Symbiotic Brain 10. The Ridd1e of Sex 11. Late Bloomers: Animals and Plants 1.2. Egocentric Man 13. The Future Supercosm
115
127 137 155 167
193 235
Nofes
277
lnilex
285
7
TABLES
1. Geological Time
4A
2. Human Classification
198
3. Acceleration in Food Production
245
4. Hierarchy Charl
247
Sizes
8
FOREWORD by Lewis Thomas, M.D. (19L3-L993), President Emeritus, Memorial Sloan-Kett ering Cancer Center
!f is on occasion the function of a foreword to provide I the reader with advance notice of what he or she may be in for. In the case of this book, unless the reader has been keeping in close touch with quite recent events in microbiology, paleontology and evolutionary biology, what he or she is in for is one great sulprise after another, even possibly one shock after another. This is a book about the inextricable connectedness of all creatures on the planet, the beings now alive and all the numberless ones that came before. Margulis and Sagan propose here a new way of looking at the world,
different from the view we mostly shared a few decades back. The new view is based on solid research, done for different reasons by many scientists in laboratories all around the earth. Brought together and linked, their findings lead to the conclusion that separateness is out of the question in Nature. The biosphere is all of a piece, an immense, integrated living system, an organism. I remember attending a series of seminars on a university 9
FOREWORD
10
campus long ago, formally entitled "Man's Place in Nature." Mostly, it had to do with how man can fix Nature up; improv-
it
so that the world's affairs might move along more agreeably: how to extract more of the Earth's energy resources, how to preserve certain areas of wilderness for our pleasure, how to avoid polluting the waterways, how to control the human population, things of that order. The general sense was that Nature is a piece of property, an inheritance, owned and operated by mankind, a sort of combination park, zoo and kitchen garden. This is still the easy way to look at the world, if you can keep your mind from wandering. Surely, we have had the appearance of a dominant species, running the place, for almost the entire period of our occupancy. At the beginning, perhaps,'we were fragile, fallible creatures, just down from the trees with nothing to boast of beyond our apposable thumbs and our exaggerated frontal lobes, hiding in caves and sfudying fire. But we took over, and now we seem to be everywhere, running everything, pole to pole, mountain peaks to deep sea trenches, colonizing the moon and eyeing the solar system. The very brains of the Earth. The pinnacle of evolution, the most stunning of biological successes, here to stay forever. But there is another way to look at us, and this book is the guide for that look. In evolutionary terms, we have only just arrived. There may be younger species than ours, here and there, but none on our scale, surely none so early on in their development. We cannot trace ourselves back more than a few thousand years before losing sight of what we think of as the real human article, language-speaking, song-singing, tool-making, fire-warming, comfortable, warmaking mankind. As a species, we are juvenile, perhaps just beginning to develop, still learning to be human, an
ing
Foraoord
11
immature child of a species. And vulnerable, error-prone still, at risk of leaving only a thin layer of radioactive fossils. One thing we need to shaighten out in aid of our perspective is our lineage. We used to believe that we arived de notso, set in place by the Management, maybe not yet dressed but ready anyway to name all the animals. Then, after Darwin, we had to face up to the embarrassment of having apes somewhere in the family tree, with chimps as cousins.
painful period in early adoleswishing them to be different, more like the parents of families down the street. There is nothing really shameful about having odd-looking hominids as parents, but still most of us would prefer, given the choice, to track our species back to pure lines of kings and queens, stopping there and looking no further. But now look at our dilemma. The first of us,. the very first of our line, appeared sometime around 3.5 billion years ago, a single bacterial cell, the Ur-ancestor of all the life to come. We go back to it, of. all things. Moreover, for all our elegance and eloquence as a species, for all our massive frontal lobes, for all our music, we have not progressed all that far from our microbial forebears. They are still with us, part of us. Or, put it another way, we are part of them. Once faced up to, it is a grand story, a marvelous epic, still nowhere near its end. It is nothing less than the saga of the life of the planet. Lynn Margulis has been spending most of her professional life studying the details of the story and has added significant details from her own scientific research. Now, she and Dorion Sagan have put it all together, literally, in this extraordinary Many children go through
a
cence when they are uncomfortable about their parents,
12
FOREWORD
book, which is unlike any treafrnent of evolution for a general readership that I have encountered before. It is a fascinating account of what is by far the longest stage in the evolution of the biosphere, the 2.5 billion year stretch of time in which our microbial ancestors, all by themselves, laid out most of the rules and regulations for interliving, habits we humans should be studying now for clues to our own survival. Most popular accounts of evolution and its problems start out just a few hundred million years ago, paying brief respects to the earliest forms of multicellular organisms and then moving quickly to the triumphant invention of vertebrate forms, making it seem as though all the time that went before was occupied by "primitive" and "simple" cells doing nothing but waiting around for the real show to begin. Margulis and Sagan fix this misapprehension of the real facts of life, demonstrating that the earliest bacteria learned almost everything there is to know about living in a system, and they are, principally, what we know today. Perhaps we have had a shared hunch about our real origrn longer than we think. It is there like a linguistic fossil, buried in the ancient root from which we take our species' name. The word for earth, at the beginning of the lndoeuropean language thousands of years ago (no one knows for sure how long ago) was dhglwn. From this word, meaning simply earth came our word humus, the handiwork of soil bacteria. Also, to teach us the lesson, humble, human, and, humane. There is the outline of a philological parable here; some of the details are filled in by this book.
PREFACE
What is the relationship between humans and Nature? The Linnaean, or scientific, name of our own species is Homo *piens sapien*"Man, the wise, the wise." But, as a humble proposal or wisecrack, we suggest that humanity be rechristened Homo insapien*"Man, the unwise, the tasteless." We love to think we are Nafure's rulers-"Man is the measure of all things," said Protagoras 2,M yeats ago-but we are less regal than we imagine. Micrrcosmos: Four Billion Years of Eaolution ftom Our Microbial Ancestors (first published in 1985) strips away the gilded clothing that serves as humanity's self-image to reveal that our self-aggrandizing view of ourselves is no more than that of a planetary fool. Humans have longbeen the planetary orbiospheric equivalent of Freud's ego, which "plays the ridiculous role of the clown in the circus whose gestures are intended to persuade the audience that all the changes on the stage are brought about by his orders." We resemble such a clown except that, unlike him, our egotism conceming our own importance for 13
14
PRE.FACE
Nature is often humorless. Freud continues, "But only the youngest members of the audience are taken in by him."s Perhaps human gullibility regarding planetary ecology is also a function of our youth