Genetics of Original Sin
Published in association with Éditions Odile Jacob for the
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current debate of ideas.
Genetics of
Original Sin
The Impact of Natural Selection
on the Future of Humanity
CHRISTIAN DE DUVE
WITH NEIL PATTERSON
FOREWORD BY
EDWARD O. WILSON
Yale
UNIVERSITY PRESS
New Haven & London
Éditions Odile Jacob
Paris
Published with assistance from the foundation established in memory of
Philip Hamilton McMillan of the Class of 1894, Yale College.
Translated from Génétique du péché originel, by Christian de Duve,
published by Éditions Odile Jacob in 2009.
Copyright Odile Jacob, 2009;
ISBN 978-2-7381-2218-6.
English-language translation copyright © 2010 by Yale University.
All rights reserved.
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Library of Congress Cataloging-in-Publication Data
De Duve, Christian.
[Génétique du péché originel. English]
Genetics of original sin : the impact of natural selection on the future of humanity /
Christian de Duve with Neil Patterson; foreword by Edward O. Wilson.
p. cm.
Includes index.
ISBN 978-0-300-16507-4 (clothbound : alk. paper) 1. Life—Origin. 2. Life (Biology) 3. Evolution (Biology) 4. Natural selection. 5. Genetics.6. Twenty-first century—Forecasts. I. Patterson, Neil. II. Title.
QH325.D41313 2010
576.8—dc22
2010029161
A catalogue record for this book is available from the British Library.
This paper meets the requirements of ANSI/NISO Z39.48–1992 (Permanence of Paper).
10 9 8 7 6 5 4 3 2 1
ALSO BY CHRISTIAN DE DUVE
A Guided Tour of the Living Cell, Scientific American Books (New York: W. H. Freeman, 1984)
Blueprint for a Cell: The Nature and Origin of Life (Burlington, NC: Neil Patterson, Publishers, 1991)
Vital Dust: Life as a Cosmic Imperative (New York: Basic Books, 1995)
Life Evolving: Molecules, Mind, and Meaning (New York: Oxford University Press, 2002)
Singularities: Landmarks on the Pathways of Life (New York: Cambridge University Press, 2005)
To Janine
“And when the woman saw that the tree was good for food, and that it was pleasant to the eyes, and a tree to be desired to make one wise, she took of the fruit thereof, and did eat, and gave also unto her husband with her; and he did eat.”
—GENESIS 3:6
Contents
Foreword by Edward O. Wilson
Preface
Acknowledgments
Introduction
Part I. The History of Life on Earth
Chapter 1. The Unity of Life
Advancing knowledge has swept away “centrisms”
Earth has a history
Life also has a history
All living beings share a number of basic properties
The history of life is written into molecular sequences
Biological evolution is an established fact 11
Opposition to evolution on religious grounds is widespread
Chapter 2. The Origin of Life
Life appeared on Earth shortly after the young planet had become physically able to harbor it
The origin of life is not known, but the only scientifically acceptable hypothesis is that it arose naturally
The building blocks of life arise spontaneously throughout the universe
Earth formed a “cauldron” in which cosmic building blocks could interact
The first steps in the origin of life were chemical in nature
The appearance of RNA was a key step in the origin of life
Chapter 3. The Evolution of Life
Microbes have left few fossil vestiges but many other traces of their long duration on Earth
Bacteria separated into two main groups
Atmospheric oxygen was a major contribution of life to Earth
The birth of eukaryotic cells inaugurated a new living world
Endosymbiosis was a key phenomenon in the development of eukaryotes
Protists are the ultimate champions of unicellularity
Multicellularity allowed division of labor
Born in water, plants were the first multicellular organisms to invade land
The evolution of animals developed around the alimentary function
Marine invertebrates inaugurated animal life
Body segmentation opened the way to vertebrates
Several distinct animal lineages moved from water to land
Dinosaurs gave rise to birds and mammals
Part II. The Mechanisms of Life
Chapter 4. Metabolism
Living cells are chemical factories
Living cells extract the energy they need from their surroundings
Thousands of specific catalysts are involved in metabolic reactions
Metabolic pathways form networks of enormous complexity
We are what our catalysts are
The history of metabolism goes back to the earliest days of life
Chapter 5. Reproduction
Reproduction started with molecular replication
With the appearance of cells, cell division was added to molecular replication in biological reproduction
Multicellular beings reproduce by way of single mother cells
The mother cell of multicellular beings arises from two parental cells by sexual reproduction
Chromosome doubling caused by sexual reproduction is corrected by meiosis during gamete maturation
Sexual reproduction is the laboratory of evolution
Male and female gametes differ
Plant reproduction involves spores
Seeds and fruits harbor, until germination, the plant embryos issued from fertilized eggs
Fungi also reproduce by way of spores
In animals, parent mobility favors union between spermatozoa and oocytes
The fertilized egg of vertebrates has always developed in an aqueous medium
Chapter 6. Development
The first accounts of embryological development were purely descriptive
Experimental embryology began to decipher developmental mechanisms
Development is ruled by transcriptional gene control
Genes are organized by transcription into a hierarchy dominated by master genes
Homeotic genes are master genes of central importance
Evolution and development are intimately linked
Chapter 7. Natural
Selection
At the start lies heredity
Artificial selection exploits the imperfections of heredity for defined purposes
Malthus introduced the notion of the “struggle for life”
Natural selection lets the “struggle for life” choose passively among the diversity created by the imperfections of heredity
Natural selection acts under our very eyes
The mutations subjected to natural selection are accidental events devoid of finality
The role of chance in evolution is limited by stringent constraints
Cases of optimizing selection are more frequent than long believed
Evolution is largely molded by environmental conditions
Certain evolutionary events could be potentially present in genomes and made manifest by favorable environmental conditions
Chapter 8. Other Evolutionary Mechanisms
Lamarck advocated the heredity of acquired characters
DNA cannot be a vector of Lamarckian heredity
Cases of Lamarckian heredity that do not involve DNA exist
Genetic drift accompanies evolution without selection
Self-organization could theoretically drive evolutionary events
Were some key evolutionary steps guided by “intelligent design”?
Part III. The Human Adventure
Chapter 9. The Emergence of Humans
Africa is the cradle of humankind
They were not yet human, but they already made stone tools
Prehumans started out of Africa for the first time some two million years ago
A second wave of migrations started once again out of Africa
The acquisition of language was a crucial step in hominization
Cro-Magnon inaugurated modern humans
What happened to the Neanderthals?
Modern humans remain the only survivors from the adventure out of which they were born
Chapter 10. Making the Human Brain
The brain is constructed with neurons
The cerebral cortex is the mysterious site of conscience
It took six hundred million years for the animal brain to reach, in chimpanzees, a volume of 21.4 cubic inches
In the human line, it took two to three million years for the brain volume to expand from 21.4 to 82.4 cubic inches
The expansion of the human brain went through a number of successive plateaus
Exponential neuron multiplication braked by anatomical constraints probably explains the sigmoid shape of the jumps of brain volume from one plateau to another
Expansion of the human brain was limited by the size of the female pelvis and by the degree of immaturity at birth compatible with survival
Chapter 11. Shaping Our Genes
Hominization involved an astonishingly small number of individuals
Hominization probably started with bipedalism, which was selectively advantageous in the local terrain
Brain expansion dominated the second major stage of hominization
The vagaries of environmental change probably guided the migrations that characterized the third stage of hominization
Hominization: Chance or necessity? Summit or stage?
Chapter 12. The Cost of Success
Taking advantage of the powers of their brains, humans have proliferated beyond all measure and exploited a major part of the planet’s resources for their own benefit
The history of humanity is a perpetual succession of wars and conflicts
The inordinate evolutionary success of the human species has been acquired at the expense of a severe deterioration of living conditions on Earth
If it continues in the same direction, humankind is headed for frightful ordeals, if not its own extinction
Chapter 13. Original Sin
Natural selection has indiscriminately privileged all the personal qualities that contribute to the immediate success of individuals
Natural selection has privileged traits favoring cohesion within groups and hostility among different groups
Natural selection has not privileged the foresight and wisdom needed for sacrificing immediate benefits for the sake of the future
Original sin is none other than the fault written into human genes by natural selection
The only possibility of redemption from the genetic original sin lies in the unique human ability to act against natural selection
Part IV. The Challenges of the Future
Chapter 14. Option 1: Do Nothing
If nothing is done, humanity is headed for disaster
The extinction of humankind, if it occurs, will be due, not to its failure, but to its success
Could a “superhuman” species succeed the human species?
Life has up to five billion years left before Earth becomes incapable of harboring it
What could happen in a brain even more developed than the human brain?
With the advent of humankind, evolution has reached a point where it is no longer a slave to natural selection
Chapter 15. Option 2: Improve Our Genes
Eugenics has become a dirty word
Cloning opens the way to directed evolution
What can cloning be used for?
Human cloning provokes heated ethical debates
Whatever happens, humanity will not be saved by cloning
Chapter 16. Option 3: Rewire the Brain
The wiring of the brain is an epigenetic phenomenon
Education starts in the cradle
Political and, especially, religious leaders are particularly well placed to propagate the recommendations the world needs
Chapter 17. Option 4: Call on Religions
Churches could play an exceptional role in saving humankind
Religions are founded on beliefs, not on rational thought
Many religions present themselves as defenders of the truth
Religious doctrines have a major impact on ethical directives
Hopes for a future life could hamper efforts in favor of present life
Are religions to be fought, or can they be enlisted?
Churches are engaged in many valuable activities
What should we do?
Ethics without doctrine is possible
The dialogue between science and religion is desirable but difficult
Religions, through their influence, and the sciences, through their knowledge, must urgently collaborate for the salvation of humanity
Chapter 18. Option 5: Protect the Environment
Protecting the environment is a very recent human concern
Ecology has penetrated daily human life
Ecology has become the source of major controversies
Nuclear energy: pro or con?
A basic discovery opened the way to revolutionary applications
GMO: an acronym that ignites passions
Are GMOs an assault against the sacredness of nature?
Environmentalism has a crucial role to play
Chapter 19. Option 6: Give Women a Chance
Combativeness is primarily a male character
In most civilizations, women are treated as inferior to men
The social rise of women in the modern world is an encouraging change
Chapter 20. Option 7: Control Population
The crisis foreseen by Malthus has struck
Culling is not a tolerable solution to the population problem
One way or another, the birthrate must be reduced
Limiting births needs to be encouraged
Epilogue
Index
Foreword
Christian de Duve has delivered a clear statement of why ours is the Century of Biology. If there is anything that science has taught us, it is that humanity is a biological species in a biological world. We originated here, grew up here, and are thoroughly adapted to this world in every fiber of our bodies and every neuronal circuit that thrums through our brain. In the fundamentals of structure a
nd development, we are not different from other organisms. And in the fine details of anatomy, we are close to our phylogenetic cousins, the great apes.
With the smooth mastery acquired by a lifetime of distinguished scientific research, Professor de Duve guides the reader through 3.5 billion years of history that led from the earliest microbes to the present-day global biodiversity, including one of its most recent productions, the hominines—us. That said, let us not stress humanity’s humble origins to the extent of devaluating the immense achievement they represent. Humans are not only the smartest creatures ever evolved, exceeding by a wide margin the nearest competitors (great apes, elephants, cetaceans), we are also the only species to create culture based upon, with each piece potentially immortal, an infinitely creative language. We alone are capable of endless histories, fantasies, and instructions.
We are nothing less than the mind of the biosphere. The achievement has been one of the major transitions of evolution, which together led from macromolecule to cell to eukaryotic cell to multicellular organism to society to the human-grade level of culture. However, whereas the earlier transitions occurred hundreds of millions or even billions of years ago, the last great transition, to the human level, occurred at best a few hundreds of thousands of years ago. It finally came to full flower in the Neolithic dawn a scant ten thousand years ago. Therein lies the dilemma identified by Professor de Duve. The earlier transitions occurred with agonizing slowness, while the human transition burst into the world as a biological supernova. Earth has not had time to adjust to this magnitude and abruptness—nor have we. The human condition is that depicted in the Star Wars movie trilogy: we have Paleolithic emotions upon which have been erected medieval institutions and godlike technology.
Having explained this dilemma in clear detail, de Duve then invites the reader to join in finding the solution or, better, ensemble of solutions. The fundamental premise in his exercise is that a knowledge of humanity’s origins and nature, by scientists and the public alike, is necessary to find the correct solution. This is the transcendent goal, truly vital in nature, that requires the best that science, religion, and political leadership can put together.
EDWARD O. WILSON
Preface
Life is the most extraordinary and perfected natural manifestation known to us. It has not ceased, ever since human beings have existed, to inspire awe and wonder. And now, for the first time in the history of humankind, knowledge and understanding have been added to those sentiments. This is a new situation. A mere four hundred years ago, it was not realised that blood flows round in a closed circuit or that living beings are made of cells; no microbe had been seen. Two hundred years ago, it was not known that infectious diseases are caused by invisible forms of life; there were no vaccines (except against smallpox, empirically introduced in 1796); no antibiotics; and it was not yet appreciated that all living beings, from microbes to humans, are part of a large family tree, born from a single root more than three and a half billion years ago. As recently as sixty years ago, knowledge of the fine structure of cells, their chemical constituents, and the fundamental mechanisms that underlie their activities was still in its infancy. Virtually nothing was known about DNA. The terms “double helix” and “genetic code” had not been invented. Today, in the space of just my own lifetime, all of these vital facts and processes have been clarified. It is no exaggeration to say that we understand life on Earth. Many details remain to be elucidated, but the essentials are known. What is probably the greatest leap in the history of knowledge has been accomplished. Such an illumination must not be kept to a few initiates.
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