Slanted Truths LYNN MARGULIS DORION SAGAN

Slanted Truths LYNN MARGULIS DORION SAGAN .......... lanted ruths ESSAYS ON GAIA, SYMBIOSIS, AND EVOLUTION FOREWORD BY PHILIP AND PHYLIS MORRISON c COPERNICUS AN IMPRINT OF SPRINGER-VERLAG © 1997 Springer-Verlag New York, Inc. Softcover reprint of the hardcover 1st edition 1997 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the publisher. Published in the United States by Copernicus, an imprint of Springer-Verlag New York, Inc. Copernicus Springer-Verlag New York, Inc. 175 Fifth Avenue New York, NY 10010 USA Library of Congress Cataloging-in-Publication Data Margulis, Lynn, 1938- Slanted truths: essays on Gaia, symbiosis, and evolution / Lynn Margulis, Dorion Sagan. p. em. Includes index. ISBN-13: 978-0-387-98772-9 e-ISBN-13: 978-1-4612-2284-2 DOT: 10.1007/978-1-4612-2284-2 1. Biology. 2. Gaia hypothesis. 3. Symbiosis. 4. Evolution (Biology) I. Sagan, Dorion, 1959- II. Title. QH311.M37 1997 57O-dc21 97-2160 Manufactured in the United States of America. Printed on acid-free paper. 987654321 To the memory and legacy of Carl Sagan 1934-1996 FOREWORD This enticing collection is as devoted to the profound power of figures of speech as any oration of old Hellas. Metaphor reigns as we encounter the identification of our Earth as a Single, integrative organism, a tale told in image and passion. The discoveries and conjectures upon which this grand view rest are here as well. I have enjoyed these two dozen pieces hugely. No family tree of animal life but must somewhere disclose a cousinly infolding. We are compact of life past, and the looped handing down is more complex than the Mendel-Morgan dance of chromosomes and genes. That dance is essential, certainly, but it is the vital editing of an epic and many-rooted work, a book more like the Bible than like one great artists Remembrance of Things Past. We follow a few old shelves of bound DNA, not just a single book. Our major biochemical package for oxidative metabolism was de scribed in a small DNA manual, somehow engulfed to become an or ganelle within a lucky ancient ancestral anaerobe, and passed ever since viii FOREWORD from mother to offspring outside of the chromosome shuffie. The sperm do carry half the compact genetic message of the human DNA, but they are too small to transfer this equally essential symbiotic one that comes down from the mothers, within roomy egg after roomy egg. Thirty years ago a bold young biologist, building a new molecular bi ology out of many early hints, entered by experience and insight into the poorly known and bizarre variety of microorganisms and their habitats. The visible tiny packaged cell components, she saw, must once actually have been free-living bacteria. Such vital organelles have long been en folded into the larger nucleated cells of all animals and plants. She is our senior author, Lynn Margulis. Most of her work was shared with her long time partner, her oldest son, the artist-philosopher Dorion Sagan. It is implausible that one-by-one assembly of hundreds of interrelated mutations made the leaves green or all animal cells oxygen users. That was rather the state of the bacterial arts very long ago, and the coded recipes worked out early on were stored in the bacteria that held the methods. They are still there to be read, if abridged. Once the larger cells incorpo rated such adept bacteria, mutuality of interest maintained the new phys ical relationship. Every individual plant or animal-you, too, reader-is a genuine mix of cells whose lineage is far more diverse than the implied parents of any centaur or chimera. Now we know that all the animals mites to whales-like all the plants-duckweed to sequoia-are symbi otic chimeras, with an architecture more like that of the lichens than like the offspring of one single family tree. Over the eons the host cells managed to bring the maintenance of their symbionts under control, so the union lost various walls and divi sions that once isolated the partners. Unrelated residual DNA instructions, much abridged by now, still accompany the organelles, far from the nuclei of the enclosing larger cells. Our biology is thus a mine of synecdoche: we name them plants and animals only by naming the whole for its part. The greenness of our countryside was a contribution of the cyanobac teria to an antique little-oxygenated world. The fuel-making seat of oxy genic energy harvest came as well from bacteria already able to use the waste product of photosynthesis, oxygen, at once powerful, toxic, and novel. Some large free cells move now only because they are manifestly rowed by symbiotic oarsmen, the once-free spirochetes. These essays speculate that the internal motility of cells with nuclei comes from the re mains of spirochetes of long ago, lately perhaps disclosed by some little pools of strange DNA. Additional multiple legacies may have entered into FOREWORD ix the early stages of life's passage to oxygenation-by no means yet ubiqui tous. Mudbanks, reef edges, bogs, and swamps still show colors that sig nal the vigor of anaerobic microbial life. These discoveries will continue. The atmosphere and the waters unite all surface life. Life is visibly a geological force, from the locust flight that carries thousands of tons of carbonaceous compounds and water across the desert, to the slow accu mulation and burial of carbon and sulfur within the limestone and gyp sum flats of the world, mediated by the long, slow work of marine plank ton. It is hard to doubt that as a principle. Its quantitative role is less surely known. Once accepted, it is tempting to try another step. That step was made first by James E. Lovelock, a scientist of great imag inative strength, out of concern with the place of organics in the vast flow of the geochemical cycles. Because life is a force at such scales, can it inhibit as well as add? The answer is surely yes. Then a nonlinear system is pretty likely to develop feedback. An ecology that feeds back from life to rock and air, and from rock and air to life again, is no very big leap. That notion, de veloped beyond our present knowledge, may imply a life-generated stability able to maintain life itself. A strong greenhouse atmosphere might have kept the Earth from freezing when the old Sun was cooler, during the first tenth or two of terrestrial history. Was that a coincidence, or a built-in response stumbled upon by the living world soon enough to help survival by favoring some special properties of its molecules? Here we are at full metaphor: regard the Earth and all its life as a new stabilizing entity, Gaia, named by Lovelock after an ancient goddess. Part III of this collection is centered on this issue, and both authors sayan en thusiastic yes to it at many levels. A physicist is a little slower to accept this response. The Sun's output and the Earth's portion of it are mainly ques tions beyond life's reach. We are possibly survivors by good fortune, like many products of natural selection. (Consult the dinosaurs at the K-T boundary for the other side of the story.) We should not multiply even metaphors without necessity. At the same time, we cannot ignore them but need to tease out the detail. If any thing is clear these days, it is the erasure of old disciplinary boundaries, the merger of opposing points of view, the increased number of examples of what once seemed unique. These arguments are here, delightfully writ ten, full of luminosity, and always honored by a firm stance on the facts. We return to part I of the pieces compiled here. One of the writers of this foreword is a little troubled by reading his own name and experiences in the first essay, written some time ago. This is no mere coincidence; the x FOREWORD places and topics are mine, engraved by experience in mind and heart. Lynn's narrative is cogent and not to be dismissed. At the same time, it is not simply a record but rather a serious docudrama woven of feelings and friendships. Its insights are those of the poet, perhaps as true as all else we can learn about old human dilemmas. Let me respond to the old piece by announcing the current optimism of an elderly physicist and his wife, long time friends of the authors. The tide of nuclear war and its possible winter have conspicuously receded. It is open to us all to prevent any re vival of that threat by continued attention, deep concern, and unity of purpose. This book of science and philosophy by a distinguished scientist at the bench and with the pen, by a gifted mother and a gifted son, is an erasure of a dark pattern of prejudice against women in science, one hard now even to credit. Yet sixty years ago that was the rule in many serious intellectual centers in the United States. The times are a-changing, not evenly, not fast, not always wisely, but they change. These pages witness such progress, by inclusion, in equity, through aesthetics, and in simple humanity. Here is good reason to hope. Philip and Phylis Morrison Cambridge, Massachusetts January 1997 - - ACKNOWLEDGMENTS This work is grounded in the deciduous forests, university campuses, and cities of the northeastern United States, mainly Boston, Woods Hole, and Amherst, Massachusetts.

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