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Excerpts from James Lovelock’s Gaia: A New Look at Life on Earth (Oxford, 1979) and The Ages of Gaia (W.W. Norton, 1988)
Of all the prizes that come from surviving more than fifty years, the best is the freedom to be eccentric. What a joy to be able to explore the physical and mental bounds of existence in safety and comfort, without bothering whether I look or sound foolish. The young usually find the constraints of convention too heavy to escape, except as part of a cult. The middle-aged have no time to spare from the conservative business of living. Only the old can happily make fools of themselves.
The idea that the Earth is alive is at the outer bounds of scientific credibility. I started to think and then to write about it in my early fifties. I was just old enough to be radical without the taint of senile delinquency. My contemporary and fellow villager, the novelist William Golding, suggested that anything alive deserves a name—what better for a living planet than Gaia (pronounced Gii'-yah), the name the Greeks used for the Earth Goddess?
I have frequently used the word Gaia as a shorthand for the hypothesis itself, namely that the biosphere is a self-regulating entity with the capacity to keep our planet healthy by controlling the chemical and physical environment. Occasionally it has been difficult to avoid talking of Gaia as if she were known to be sentient. This is meant no more seriously than is the appellation "she" when given to a ship by those who sail in her, as a recognition that even pieces of wood and metal may achieve a composite identity distinct from the mere sum of its parts.
The concept of Mother Earth has been widely held throughout history and has been the basis of a belief which still coexists with the great religions. As a result of the accumulation of evidence about the natural environment and the growth of the science of ecology, there have recently been speculations that the biosphere may be more than just the complete range of all living things within their natural habitat of soil, sea, and air. Ancient belief and modern knowledge have fused emotionally in the awe with which astronauts with their own eyes and we by indirect vision have seen the Earth revealed in all its shining beauty against the deep darkness of space. Yet this feeling, however strong, does not prove that Mother Earth lives. Like a religious belief, it is scientifically untestable.
Journeys into space did more than present the Earth in a new perspective. They also sent back information about its atmosphere and its surface which provided a new insight into the interactions between the living and the nonliving parts of the planet. From this has arisen the hypothesis in which the Earth's living matter, air, oceans, and land surface form a complex system which can be seen as a single organism and which has the capacity to keep our planet a fit place for life.
Interdisciplinary Pilgrim
This book (Oxford, 1979) is a personal account of a journey through space and time in search of evidence with which to substantiate this model of the Earth. The quest began in the mid-1960s and has ranged through territories of many different scientific disciplines, indeed from astronomy to zoology.
Such journeys are lively, for the boundaries between the sciences are jealously guarded by their Professors and within each territory there is a different arcane language to be learnt. In the ordinary way a grand tour of this kind would be extravagantly expensive and unproductive in its yield of new knowledge; but just as trade often still goes on between nations at war, it is also possible for a chemist to travel through such distant disciplines as meteorology or physiology, if he has something to barter.
Usually this is a piece of hardware or a technique. I was fortunate to work briefly with Archer Martin, who developed the technique of gas chromatography. During that time I added some embellishments which extended the range of his invention. One of these was the so-called electron capture detector. This device has exquisite sensitivity in the detection of traces of certain chemical substances. This sensitivity made possible the discovery that pesticides were present in all creatures of the Earth, from penguins in Antarctica to the milk of nursing mothers in the United States. It was this discovery that facilitated the writing of Rachel Carson's influential book. Silent Spring, by providing evidence needed to justify her concern over the damage done to the biosphere by the ubiquitous presence of these toxic chemicals.
The electron capture detector has continued to reveal minute but significant quantities of other toxic chemicals in places where they ought not to be. Among these intruders are: PAN (peroxyacetyl nitrate), a toxic component of Los Angeles smog; the PCBs (polychlorobiphenyls) in the remote natural environment; and most recently, in the atmosphere at large, the chlorofluorocarbons and nitrous oxide—substances which are thought to deplete ozone in the stratosphere.
Electron capture detectors enabled me to pursue my quest for Gaia through various scientific disciplines, and also to travel around the Earth itself. Although my role as a tradesman made interdisciplinary journeys feasible, they have not been easy, since these past several decades have witnessed a great deal of turmoil in the life sciences, particularly in areas where science has been drawn into the processes of power politics.
The Search for Life on Mars
The concept that the Earth is actively maintained and regulated by life had its origins in the search for life on Mars. It all started one morning in the spring of 1961 when the postman brought a letter that was for me almost as full of promise and excitement as a first love letter. It was an invitation from NASA to be an experimenter on its first lunar instrument mission.
Space is only a hundred miles away and is now a common place. But 1961 was only four years after the Soviet Union had launched the first artificial satellite, Sputnik. To receive an official invitation to join in the first exploration of the Moon was a legitimization and recognition of my private world of fantasy. My childhood reading had moved on that well known path from Grimm's Fairy Tales through Alice's Adventures in Wonderland to Jules Verne and H G Wells. I had often said in jest that it was the task of scientists to reduce science fiction to practice. Someone had listened and called my bluff.
My first encounter with the space science of NASA was to visit that open plan cathedral of science and engineering, the Jet Propulsion Laboratory, just outside the suburb of Pasadena in California. Soon after I began work with NASA on the lunar probe, I was moved to the even more exciting job of designing sensitive instruments that would analyze the surfaces and atmospheres of the planets. My background, though, was biology and medicine, and I grew curious about the experiments to detect life on other planets. I expected to find biologists engaged in designing experiments and instruments as wonderful and exquisitely constructed as the spacecraft themselves. The reality was a disappointment that marked the end of my euphoria. I felt their experiments had little chance of finding life on Mars, even if the planet were swarming with it.
When a large organization is faced with a difficult problem the standard procedure is to hire some experts, and this is what NASA did. This approach is fine if you need to design a better rocket engine. But if the goal is to detect life on Mars, there are no such experts. There were no Professors of Life on Mars, so NASA had to settle for experts of life on Earth. These tended to be biologists familiar with the limited range of living things that they work with in their Earth-bound laboratories.
So the planning of experiments was mostly based on the assumption that evidence for life on Mars would be much the same as for life on Earth. Thus one proposed series of experiments involved an automated microbiological laboratory to sample the Martian soil and judge its suitability to support bacteria, fungi, or other micro-organisms. Additional soil experiments were designed to test for chemicals whose presence would indicate life at work: proteins, amino acids, and substances with the capacity that organic matter has to twist a beam of polarized light in a counter-clockwise direction.
After a year or so, I found myself asking some rather down-to-earth questions, such as, "How can we be sure that the Martian way of life, if any, will reveal itself to tests based on Earth's life style?" To say nothing of more difficult questions, such as, "What is life, and how should it be recognized?"
What Is Life?
Back home in the quiet countryside of Wiltshire, England, after my visits to the Jet Propulsion Laboratories, I had time to do more thinking and reading about the character of life and how one might recognize it anywhere and in any guise. I expected to discover somewhere in the scientific literature a comprehensive definition of life as a physical process, on which one could design life-detection experiments, but I was surprised to find how little had been written about the nature of life itself. The present interest in ecology and the application of systems analysis to biology had barely begun, and there was still in those days the dusty academic air of the classroom about the life sciences.
Data galore had been accumulated on every conceivable aspect of living species, from their outermost to their innermost parts, but in the whole vast encyclopedia of facts the crux of the matter, life itself, was almost totally ignored. At best, the literature read like a collection of expert reports, as if a group of scientists from another world had taken a television receiver home with them and had reported on it. The chemist said it was made of wood, glass, and metal. The physicist said it radiated heat and light. The engineer said the supporting wheels were too small and in the wrong place for it to run smoothly on a flat surface. But nobody said what it was.
This seeming conspiracy of silence may have been due in part to the division of science into separate disciplines, with each specialist assuming that someone else has done the job. Some biologists may believe that the process of life is adequately described by some mathematical theorem of physics, and some physicists may assume that it is factually described in the recondite writings on molecular biology which one day he will find time to read. But the most probable cause of our closed minds on the subject is that we already have a rapid, highly efficient life-recognition program in our inherited set of instincts.
Our recognition of living things, both animal and vegetable, is instant and automatic, and our fellow-creatures in the animal world appear to have the same facility. This powerful but unconscious recognition no doubt evolved as a survival factor. Anything living may be edible, lethal, friendly, aggressive, or a potential mate—all questions of prime significance for our welfare and continued existence.
Some of my colleagues at the Jet Propulsion Laboratories mistook my growing skepticism for cynical disillusion and quite properly asked, "Well, what would you do instead?" At that time I could only reply vaguely, "I'd look for an entropy reduction, since this must be a general characteristic of all forms of life." Understandably, this reply was taken to be at the best unpractical and at worst plain obfuscation, for few physical concepts can have caused as much confusion and misunderstanding as has that of entropy.
Entropy is almost a synonym for disorder and yet as a measure of the rate of dissipation of a system's thermal energy, it can be precisely expressed in mathematical terms. It has been the bane of generations of students and is direfully associated in many minds with decline and decay, since its expression in the Second Law of Thermodynamics (indicating that all energy will eventually dissipate into heat universally distributed and will no longer be available for the performance of useful work) implies the predestined and inevitable run-down and death of the Universe.
During this century a few physicists have tried to define life. Bernal, Schroedinger, and Wigner all came to the same general conclusion, that life is a member of the class of phenomena which are open or continuous systems able to decrease their internal entropy (thereby increase order) at the expense of substances or free energy taken in from the environment and subsequently rejected in degraded form. A rough paraphrase might be that life is one of those processes which are found whenever there is an abundant flow of energy. It is characterized by a tendency to shape or form itself as it consumes, but to do so it must always excrete low-grade products to the surroundings.
We can now see that this definition would apply equally well to eddies in a flowing stream, to hurricanes, to flames, or even to refrigerators and many other man-made contrivances. A flame assumes a characteristic shape as it burns, and needs an adequate supply of fuel and air to keep going, and we are now only too well aware that the pleasant warmth and dancing flames of an open fire have to be paid for in the excretion of waste heat and pollutant gases. Entropy is reduced locally by the flame formation, but the overall total of entropy is increased during the fuel consumption.
Atmospheric Clues
Yet even if too broad and vague, this classification of life at least points us in the right direction. It suggests, for example, that there is a boundary or interface between the "factory" area and the surrounding environment which receives the waste products. It also suggests that life-like processes require a flux of energy above some minimal value in order to get going and keep going. Assuming that life on any planet would be bound to use the fluid media—oceans, atmosphere, or both—as conveyor belts for raw materials and waste products, it occurred to me that some of the activity associated with entropy reduction within a living system might spill over into the conveyor-belt regions and alter their composition. The atmosphere of a life-bearing planet would thus become recognizably different from that of a dead planet.