Genetics of Original Sin (2 page)

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 and 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.

E
DWARD
O. W
ILSON

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.

This is all the more true because it's not just about the life that surrounds us; it's about our own nature, our own history as a form of life. One of the most important revelations of modern science has been the discovery that we are part of the great network of life. We are not only its spectators and beneficiaries, as long believed. We are born from it and share its basic properties with all other living beings on this planet. In addition, we have specifically human traits that we owe to our brains. Understanding life means understanding ourselves.

There are more practical reasons why it is important for all of us, and in particular our political, cultural, economic, and religious leaders, to be informed about the nature and history of life. Our understanding of basic biological mechanisms has spawned powerful means to manipulate life. Cloning, in vitro fertilization, stem cells, DNA tests, genetically modified organisms: these terms and others have become part of common vocabulary and should be understood by everyone. This requirement does not just concern specialized notions. Many questions of interest for our daily existence—health, food, hygiene, economy, environment, and so on—are linked one way or another to what we know—or ought to know—about the properties of living beings. The term “bio” has gained an almost mystic connotation. But rare are those who may sensibly claim that they understand with some precision what it's all about.

The most important and urgent reason why it is now imperative that every responsible citizen be informed of recent developments in the life sciences is that
we need this knowledge
in order to face the future in a constructive way. The present book addresses this issue. It is the outcome of a thirty-year voyage of discovery, chronicled in five successive books, which has led me from lysosomes and peroxisomes, the cell organelles that were long the sole focus of my laboratory research, first to all aspects of cellular organization (
A Guided Tour of the Living Cell
), then to the basic properties of life and to its origin (
Blueprint for a Cell: The Nature and Origin of Life
), to its evolutionary history, including the advent of humankind (
Vital Dust: Life as a Cosmic Imperative),
and, finally, to the “meaning of it all” (
Life Evolving: Molecules, Mind, and Meaning
). At the end of the journey, I completed this series, which was largely addressed to the general public, with a concise summary aimed at a more scientifically literate readership (
Singularities: Landmarks on the Pathways of Life
). This was to be the end of my literary expedition. My neuronal telomeres decided differently. (Highlighted by the 2009 Nobel Prize in medicine, telomeres are DNA “tails” attached to the ends of chromosomes that shorten progressively in the course of successive cell divisions. Their preservation and/or repair are linked to increasing cellular longevity.)

Having been granted the time to do so, I have been prompted to go one step further, this time back to the past and into the future. It turned out to be not just a pleasing intellectual pastime but an effort to meet a pressing need. The future of life on Earth, in particular human life, is under serious threat. Climate change, deforestation, desertification, water shortage, famine, loss of biodiversity, depletion of natural resources, growing energy needs, pollution, new diseases, overcrowded megalopolises, conflicts, and wars are daily brought to our attention by the media. These menaces are recognized and burgeoning. Yet responses so far have been sluggish, to say the least. The vague and slight results of the recent Copenhagen conference on climate illustrate humanity's inability to come to grips with threats that extend beyond the immediate future.

It occurred to me that the causes of this worrisome situation, both the menaces and our lack of constructive response, are to be found in our nature, itself the product of a long history that I had attempted to reconstruct and explain in previous books. The “culprit,” in this scientific interpretation of the myth of “original sin,” is natural selection, which has sustained in our genes the traits that proved immediately useful to the survival and reproduction of our ancestors but have now become dangerously harmful. If we wish to escape the fate that awaits us, we must take advantage of our unique ability to consciously and deliberately act against natural selection. Such is the object of this book.

The work is addressed to as wide a readership as possible, not necessarily acquainted with science or trained in its way of thinking, but adequately informed of world affairs. For this reason, I have avoided all technical terms and left out the customary notes and references that would be needed in a more scholarly opus. I have also mostly refrained from mentioning quantitative data readily available elsewhere. But I do explain, in passing, some of the new biotechnological tools, such as cloning and genetic engineering, offered by modern science to a society that distrusts them and urgently needs clarification on the topic.

I cannot end this preface without recalling with deep sorrow the memory of my dear Janine, lost to my affection after sixty-five years of life together, just as I was finishing the first draft of this book. She used to read each chapter as soon as it came out of my computer and never failed to make judicious comments, all the more valuable because, as a professional artist, she cast a fresh look on my writings. I dedicate what is probably my last work to her beloved memory, on the day of what would have been her eighty-eighth birthday.

Nethen and New York, 6 April 2010

As I have done for earlier works, I wrote this book concurrently in my two mother languages, English and French. The two versions have benefited reciprocally from the criticisms, comments, and suggestions addressed to the other.

Many people have helped to make this work possible. Among them, I owe special tribute to my faithful editor and longtime friend Neil Patterson, who once again has favored me with his invaluable help, not only in purging my style of gallicisms, grammatical errors, obscure statements, needless repetitions, and flowery expressions, but also in critically assessing the substance. His participation has far exceeded a strictly editorial assistance and has justified his designation as coauthor. I am particularly pleased to publish this new work with him, after more than twenty-five years of friendly and effective, if sometimes heated, collaboration.

I am particularly indebted to my valued friend Odile Jacob, who not only has published two of my previous books before this one but has, in addition, decided to include my latest opus in her joint enterprise with Yale University Press. It is a great honor. I also address my most grateful thanks to the members of her staff, including Gérard Jorland, Émilie Barian, and Claudine Roth-Isler, for their excellent collaboration.

I owe a similar debt of sincere gratitude to Yale University Press for publishing the English version of the book and, especially, to Jean Thomson Black for her competent and understanding assistance, to Laura Jones Dooley for her thorough editorial revision of the manuscript (with my apologies for not always following her recommendations), and to Jaya Chatterjee for her valuable help with illustrations.

Finally, I wish to thank my trusted Brussels assistant, Monique Van de Maele, for her invaluable help in the search for needed information and her colleague, Nathalie Chevalier, who has expertly assembled the illustrations common to both versions. I am also indebted to Xavier de Felipe for his wonderful reconstruction of the “forest of neurons” reproduced in
figure 10.1
and to Gabriel Ringlet for valuable criticisms and suggestions.

The sacred writers who invented the famous myth, immortalized by numerous artists and writers across the centuries, of Original Sin that allegedly cost the first parents of humanity to be expelled from the Earthly Paradise, have not just displayed lively poetic imagination. They have, in addition, shown remarkable perspicacity—apart from their choice, which was far from innocent, of a woman as culprit. They have perceived the presence in human nature of a fatal flaw, which, as they saw it, only divine intervention could possibly repair. Hence the hope for an envoy from God, a Messiah, Savior, or Redeemer, whom some believe to have appeared two thousand years ago and others are still awaiting.

Modern science has rendered the biblical account untenable, without, however, invalidating the intuition that may have inspired it. Humankind is indeed tainted by a fundamental defect, bound, in all probability, to bring about its demise. The culprit is not Eve, but natural selection. There is indeed a need for a redeemer. But that redeemer will not come from heaven; only humankind can serve that role.

In this predicament, the wisdom of our forebears is of little help to us today, because the wise of yesteryear could not foresee the present crisis. But their recommendation that we should take advantage of the lessons of the past to prepare the future remains timely. What humanity needs now is a new form of wisdom inspired by what we have learned about the nature and history of the living world to which we belong, about our place in it, and about the manner in which we have reached it.

Such is the thesis I develop in this book, adopting as main guide life itself, as we have learned to understand it, with as illuminating beacon natural selection, the mechanism discerned by the genius of Charles Darwin, who has been celebrated in 2009 by a dual anniversary, the 200th of his birth and the 150th of the first publication of his magnum opus,
On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life.

This book is divided into four parts, each of which stands more or less on its own. To start, I retrace briefly a number of basic notions about the nature, origin, and evolutionary history of life on Earth. I do so in a strictly descriptive fashion, leaving an analysis of the underlying mechanisms to the second part.