Homage to Gaia (42 page)

One afternoon in September 1965, I was in the Space Science Building of JPL in a small office that looked out towards the mountains. The astronomer, Lou Kaplan, had brought in the infrared spectrum charts of the latest sightings from the Pic de Midi Observatory in France. They provided a detailed analysis of the chemical composition of the atmospheres of Mars and Venus and for the first time we saw that both planets had atmospheres dominated by carbon dioxide, with only traces of other gases present. As I had suspected, the cratered, moonlike Mars had an atmosphere close to chemical equilibrium, and it was profoundly different from the rich and anomalous atmosphere of Earth. Our sibling planets had atmospheres as barren and lifeless as the regolith of the Moon, but here our own air has oxygen mixed with methane, and carbon dioxide is a mere trace at only 300 parts per million. Even nitrogen, the dominant gas of the air, makes no sense. The stable form of the element nitrogen is not the gas in the air but the nitrate ion dissolved in the ocean. The distinguished American physical chemist, GN Lewis had proved
this in the 1920s. Nitrogen in the air is always reacting with oxygen to form nitric acid, which dissolves in the sea to form the stable nitrates, and they would stay there but for the ceaseless activity of bacteria, which return the nitrogen to the air. Looked at as a whole, our atmosphere is a combustible mixture. More than this, it is in a sense continuously burning. This is because the shorter wavelength of sunlight, the far ultraviolet that illuminates the upper part of the atmosphere, can in effect ignite the combustion of gases such as methane and oxygen. It is what the chemists call a cool flame, and it has been burning for hundreds of millions of years. The combustion of the air is no mere metaphor—it really happens—and distinguished physical chemists like Sir David Bates of Queen’s University, Belfast and Marcel Nicolet, in Brussels, were then wondering about its nature and significance.

Until that afternoon, my thoughts on planetary atmospheres had been wholly concerned with atmospheric analysis as a method of life detection and nothing more. Now that I knew the composition of the Martian atmosphere was so different from that of our own, my mind filled with wonderings about the nature of the Earth. If the air is burning, what sustains it at a constant composition? I also wondered about the supply of fuel and the removal of the products of combustion. It came to me suddenly, just like a flash of enlightenment, that to persist and keep stable, something must be regulating the atmosphere and so keeping it at its constant composition. Moreover, if most of the gases came from living organisms, then life at the surface must be doing the regulation. I blurted out my intuition to my colleague Dian Hitchcock and to the cosmologist Carl Sagan. There was little comment at the time. Afterwards Carl told me about the paradox of the cool Sun. Our star has not always been as bright as it is now, and in the beginning, it was thought to be some twenty-five to thirty per cent less luminous. The puzzle was, if this was so, how is it that the geological record suggests that, apart from a few brief ice ages, the Earth has always been warm. A twenty-five per cent drop in luminosity with our present atmosphere would freeze much of the Earth’s surface and oceans. As Pasteur and others have said, ‘Chance favours the prepared mind.’ My mind was well prepared emotionally and scientifically and it dawned on me that somehow life was regulating climate as well as chemistry. Suddenly the image of the Earth as a living organism able to regulate its temperature and chemistry at a comfortable steady state emerged in my mind. At such moments,
there is no time or place for such niceties as the qualification ‘of course it is not alive—it merely behaves as if it were’.

By this time the distinguished biologist, Norman Horowitz, had taken charge of JPL biology; he was also Professor of Biology at that famous university, Cal Tech, which was not far from JPL. Norman was an amiable man who reminded me of the playwright Arthur Miller. He was open-minded, and although he disagreed with my views about the Earth and its atmosphere, he thought, as the good scientist he was, that they should be heard. Two years later, in 1967, he arranged for me to present the first paper on my idea of a self-regulating Earth system at a meeting of the American Astronautical Society in Lansing, Michigan. The space scientists and engineers who were there received my account of the Earth as a quasi-living system enthusiastically. This is not so surprising because engineers understand the concept of feedback and the way systems work; they share this understanding with physiologists. Norman Horowitz and I shared the opinion that there was no need to sterilize the Martian landers. The concept of contaminating a virginal Mars with earth-type life seemed the stuff of fanatics, not scientists, and the act of sterilization hazarded the delicate and intricate instruments we wanted to send to Mars.

In the next year, 1968, Princeton University hosted a more academically significant meeting, and here I met for the first time Lynn Margulis and the Norwegian scientist, Lars Sillen. This distinguished geochemist was the first Earth scientist I had met who was prepared to listen to my thoughts on a self-regulating Earth and consider them as science. Also present were some of the most prominent members of the United States geological community, and Philip Handler, who was later to become President of the National Academy of Sciences, chaired the meeting together with Norman Horowitz. Lynn Margulis, as the youngest member present, had the job of rapporteur, and she published her account as a book in the series, The Origins of Life. Perhaps the task of reporting everything we said was onerous and she had no time or opportunity to think about it. Certainly, I had no contact or discussion with her at the meeting. My fruitful collaboration with Lynn was not to begin until some time later. For me the meeting was fascinating, but frustrating because senior American scientists were then heavily authoritative. These eminent professors expected young scientists like Lynn and me to be seen but not heard; we were there to be used, not to have opinions.
Consequently, whenever I raised my strange views about the atmosphere they either ignored them or brushed them aside as irrelevant. Towards the end of the meeting, when I asked somewhat plaintively for a chance to get a word in edgeways, Norman Horowitz and Lars Sillen came to my rescue. There are a few of my words about our strange and anomalous atmosphere reported in
Proceedings
of
the
Second
Conference
on
Origins
of
Life
and published in 1971 by Gordon and Breach of New York.

Around about this time I started my first visits to the National Center for Atmospheric Research at Boulder in Colorado (NCAR) and it soon became a regular stopping place on my visits to JPL. It is probably the most beautiful scientific institute in the world and sited on Table Mesa well above the small city of Boulder, its shapely natural stone edifice is like a cathedral. On most visits there I would ask the directors, who included Walter Orr Roberts and Will Kellog, when they would open a department of biology at NCAR. Although I meant it seriously, it was good for a laugh in those days, but now there are biologists there and among them Lee Klinger who has pioneered the role of peat bogs as an ecosystem of global significance. Boulder is also the home of NOAA laboratories and the University of Colorado. It is a science city where my friends Robert Sievers and Adrian Tuck also live. Bob Sievers and I share a long history of instrument development and Adrian Tuck was my constant contact at the Meteorological Office in England before he left for Boulder.

The novelist, William Golding, suggested the name Gaia for my notions about a self-regulating Earth. He and his wife Ann were friends who lived in a large thatched house near where the river Ebble sprang from the chalk at the lowest part of the village of Bowerchalke. Bill had taught history at the Bishop Wordsworth school in Salisbury but the success of his novel
Lord
of
the
Flies
enabled an independent life. He had the comfortable air and casual way of dress that justly earned him, when he was a schoolmaster, the nickname Scruffy. We would often meet in the Bell, the village pub, and exchanged visits to talk on some particular subject of mutual interest such as science fiction or space research. One morning when walking up the village road, I overtook Bill who was on his way to the post office. We began talking and he asked me about my latest trip to JPL. Bill had had a scientific, as well as a classical education, and he was warmly appreciative of my tale about a self-regulating planet. After we had walked and talked well beyond the post office, Bill
turned to me and said, ‘If you want to propagate a large theory about the Earth you had better give it a proper name. I suggest that you call it Gaia.’ We walked on and continued talking for some time, but at cross-purposes: I thought that he had suggested calling the theory ‘Gyre’ after one of the great whirls of the atmosphere and the ocean. When he put me right by explaining that he meant the Gaia of mythology, the Greek goddess of the Earth, I was deeply grateful. Few scientists have had their theories named by so competent a wordsmith.

Biologists have attacked the name Gaia and the metaphor of a living Earth as if I intended them as fact. I now think they did this from an instinctive dislike of holistic ideas, not because they were greedy over metaphors. I never begrudged them ‘The Selfish Gene’, ‘The Red Queen’, or the ‘The Blind Watchmaker’. Nor do I pedantically argue that to be selfish a gene would have to take thought and have purpose. Their attack on the metaphor of Gaia, the living Earth, was not a proper scientific criticism: it was a gut reaction to an unwelcome theory. Not all biologists were hostile. There was the friendly scepticism of that most eminent scientist EO Wilson, whose recent book
Consilience
reveals the breadth of his wisdom. The Nobel Laureate, Christian de Duve, in his book
Vital
Dust,
gave Gaia a fair hearing and Norman Myers, when he edited the famous
Gaia
Atlas
of
Planetary
Management,
did homage to the name Gaia.

My first correspondence with Lynn Margulis on the science of Gaia was in the summer of 1970. Lynn had begun to wonder about the significance of oxygen in the atmosphere and had asked Carl Sagan, her former husband, who would be his first choice of scientist to ask about atmospheric oxygen. Strangely, Carl recommended me: had I been him I would have named either GE Hutchinson, the founder of biogeochemistry or LV Berkner who, with LC Marshall, had recently written a monograph on atmospheric oxygen. Soon after, I received a letter from Lynn inviting me to visit her lab on my next visit, but it was not until late in 1971 that I was able to accept. My memory of that first meeting is sketchy and mingled with numerous others in the years to come. I seem to recall Lynn meeting my flight at Boston’s Logan airport in December 1971, and that we travelled to her lab at Boston University on a subway train. Our exchange there was enthusiastic and Lynn’s deep understanding of microbial ecology impressed and influenced me; she was the first biologist I had met who had a feeling for the organism. After that, a bacterium
ceased for me to be merely a membrane bag holding some genes and proteinaceous mechanisms which could reproduce itself, and nothing more. Lynn’s empathy with microbial communities has greatly enriched our understanding of Gaia and of the importance of the microbial sector in the whole system. She explains it in a book written with her son Dorion Sagan,
Microcosmos,
and most recently in
Symbiotic
Earth.

It was a coming together of minds that led to many more visits and for several years, Boston was my first port of call on visits to the USA. So amiable were our meetings in the early 1970s that after one of them Lynn felt the need to set the ground rules for our continuing association. We sat in Logan airport waiting the call for my return flight and she turned to me and with great seriousness said that we must meet as scientific colleagues and nothing more. I agreed without any sense of regret; it is rare for close scientific collaborations to evolve into romances.

During those years, I enjoyed my visits to Boston. Lynn Margulis and her family always made me welcome at their home in Newton. She was then married to Nicholas Margulis and with four children in the house—Dorion and Jeremy, children of her first marriage to Carl Sagan, and Zach and Jenny from her marriage to Nicky Margulis—it was a lively family. The atmosphere was turbulent, warm, and familiar. Lynn and I worked closely and harmoniously together. We had a few arguments. The ones I remember most were about Vernadsky. I agreed with Lynn that he had anticipated some of our ideas, but I disagreed with her about his position in the pantheon of science. I could not see him as one of science’s great figures, like Galileo or Darwin. His statement, ‘Life is a geological force’, certainly captured one part of Gaia theory, but I am unimpressed by those who merely talk or write about an idea without doing experiments or presenting models and theories that we can challenge. Moreover, like so many contemporary scientists, he did not seem to have a feeling for system science and the tight-coupled feedback between life and its environment. I did not understand Lynn’s need to single out Vernadsky for special praise when there were so many others who had trodden the same path as we were on. I was sure that James Hutton, TH Huxley, Friederich Humbolt, Lawrence Henderson, AC Redfield, and most of all Eugene Odum, GE Hutchinson and Alfred Lotka were scientists as deserving of recognition as our predecessors. I suspect that we were arguing about legends, not science.

On most other things, Lynn and I supported and complemented each other wonderfully. Her broad experience and wisdom about living things, especially about micro-organisms, put flesh on the bare bones of my skeleton of Gaia. I shall never forget her welcome when I went to Boston University straight from the airport, and her enthusiasm as she told me about the snail in Brittany that lives in part by photosynthesis like a plant. What a metaphor: ‘The solar-powered snail.’ Lynn had her own battles with the ponderous scientific establishment, mainly over her support for the endosymbiont hypothesis. As with Gaia, they now take for granted that organelles, like mitochondria and chloroplasts, were once free-living organisms, and that at some step in evolution they entered a symbiotic relationship with their eukaryotic hosts. However, Lynn’s contribution to this discovery is too rarely mentioned. William James was so right when he said that the fate of a new idea follows the pattern: at first absurd, then maybe true, and, finally, we knew it all along.