As a frequent attender at Gordon Conferences I enjoyed the fringe benefits such as climbing one of the small granite mountains near New Hampton, the site of the 1971 conference. The guide who led us up Mount Cardigan was dubious about my capacity, at fifty-one years old, to keep up with younger men and women who had chosen to spend their afternoon this way. Having climbed Snowdon, a Welsh mountain of the same height, by the exciting Crib Goch the previous year, I told him that I thought I could manage. It was a glorious afternoon walk up a rocky pass, first through a pine forest and clear streams, and then up onto the smooth assembly of granite slabs, mostly bare, that led to the mountain top. As always, at the top there was a feeling of achievement and the reward of a grand view of the lakes and mountains of northern New England. I must admit to having misjudged the beauty of the New England countryside. New Hampshire, Vermont, and Maine were more attractive to me than the states further south.
The next afternoon I spent swimming in the lake and then walking along its beach with the German scientist Dieter Ehalt from NCAR. We talked about methane. Dieter was the acknowledged leader of research on the production and fate of this important atmospheric gas. I had long been interested in its significance as evidence for a self-regulated atmosphere and one of the props of Gaia theory. As we passed a small, slow-moving stream that flowed into the lake, Dieter took a stick and stirred the black detritus at the bottom of the stream. A burst of bubbles came forth. ‘There’s the methane,’ he remarked. I had known that about 500,000,000 tons of the gas escaped from the ground into the air each year, but this simple demonstration fixed forever in my mind its reality. My long-time friend from Boulder, Jim Lodge, had organized this Gordon Conference on Atmospheric Chemistry and it was an outstanding success. The thirty years of important and exciting atmospheric science that followed owed their start to that meeting. We talked of future climates, the effect of greenhouse gases and the cooling by clouds and aerosols. We discussed at length the chemical cycles of the elements. Here, also, I presented my measurements of the atmospheric abundance of CFCs and DMS.
At this same meeting, Joe Prospero talked about atmospheric aerosols and the composition of dust collected at stations in Florida and even in Hawaii. I was amazed to hear that Sahara dust blew all the way across the Atlantic and even into the Pacific. We also argued over the super abundance of elements such as sulphur, selenium, iodine and zinc in the aerosol particles. I speculated that perhaps biological methylation rendered these elements volatile and carried an excess of them into the atmosphere. Here were the first steps towards the discovery years later with Bob Charlson, Andi Andreae, Steve Warren, and myself that clouds, dimethyl sulphide from algae living in the ocean, and climate, are all intimately linked in a great ocean atmospheric cycle. My report at this meeting on the prevalence of CFCs in the troposphere led Lester Machta later to alert Sherry Rowland to this source of chlorine in the atmosphere, and to the recognition that chlorine in the stratosphere might catalytically deplete the ozone there.
GD Robinson came to me one afternoon and said, ‘Could you give us a ten to fifteen-minute talk on Gaia after dinner tonight?’ He introduced me that evening as someone who would entertain them with a flight of fancy. It was my first talk on Gaia to an audience of atmospheric scientists and I published it in Atmospheric Environment two years later with the title ‘Gaia as seen through the atmosphere’.
During the 1970s and until 1982, when I fell ill, Lynn Margulis and I spent as much of our time developing Gaia as we could. Neither of us received support for our work, and both of us were busy with other work. Lynn had her teaching and other duties at Boston University, and I had my customers, as well as the burgeoning ozone depletion research. We published two important joint papers. I wrote the first, ‘Atmospheric homeostasis by and for the biosphere: the Gaia hypothesis’, and it expresses Gaia as I then saw it. The second, ‘Biological modulation of the Earth’s atmosphere’, Lynn wrote, and it expresses her view of Gaia. These titles reveal our ignorance then of the fact that regulation is a property of the whole system of life and its environment, not just life itself. A high spot in this period was an expedition organized by Lynn, who gathered the funds to enable a party of scientists to visit Baja California and do research on the algal mats there. She took us from San Diego to Laguna Figueroa, a place about 200 miles down the Baja California peninsula. Algal mats are the communities of micro-organisms whose ancestry dates back to the Earth’s earliest history and may have played a huge part in regulating the Earth system over the whole of that time.
We met in a small hotel near the Scripps Institute at La Jolla, a cosy, wealthy institute, and so well sited on the shore of the Pacific. Almost as comfortable, I thought, as Coombe Mill. We travelled south in two people-carriers and passed across the border and through the dismal town of Tijuana, and then down the Baja peninsula itself. The real Mexico revealed itself as we travelled south. When we arrived at our destination, we found that we were booked into a small hotel. Having suffered from eating at American–Mexican restaurants, I rather dreaded a week of Mexican food. I could not have been more wrong. The food at our hotel was magnificent, and I found myself looking forward with anticipation to every meal. National cuisine gets a bad name from its restaurants in the capital cities of the western world.
Along the edges of the continents, earth movement and the drifting of sand and shingle forms lagoons that trap ocean water. In the warmer parts of the world, these lagoons lose more water by evaporation than they gain from rainfall or from sea water leaking in from the ocean. Consequently, the salt in the water concentrates until it crystallizes to form what the geologists call an evaporite deposit. This process has been going on since the beginning of time and we find evaporite beds buried under sediments all over the world. They form the huge salt deposits, like the one that runs across northern Europe a few hundred feet below the surface and is made notorious by the salt mines of Eastern Europe. The algal mats sit on top of these evaporite beds. Lynn, her student, Greg Hinkel, and I speculated about the role of these mats in sustaining salt in the beds, and so keeping the ocean below the critical salt level of 0.8 molar. Above this salinity, organisms find it hard to survive. I watched as Lynn cut out with a small spade a cube of the mat four inches in size. We looked at its banded structure: each band was a different community of micro-organisms segregated according to the flow of nutrients and oxygen. Lynn showed how similar was this banded structure to that of the fossil mats over two billion years old. I was convinced by her lucid explanations that micro-organisms are the heart of Gaia and always have been.
On one occasion, I went with Lynn, her daughter, Jenny, and a French au pair girl, to another Gordon Conference in New Hampshire. We gave our Gaia talks and soon discovered that we were not there as serious scientists but more as entertainment. The serious business of the conference, we discovered, focused on arcane topics dear to the timber industry. This allowed us plenty of time to explore the New Hampshire Mountains. We had just climbed one peak and were making our way down over the granite boulders and small shrubs, talking passionately about a Gaian problem, when suddenly we found ourselves deep in the forest. We were lost. Lynn gave a cry: ‘There are thousands of miles of nothing between here and Canada and if we go the wrong way they will find our bodies in the spring.’ We tried to retrace our path, and with luck, came upon a logger’s trail, which we followed down to the road, but it was a scary moment. As time went by, Lynn and I saw less of each other, mainly because the forces of family life and work were dispersive not cohesive. It was the best of my lifetime collaborations and was a platonic relationship that kept in a lively steady state. The sad events in both our families conspired to separate us as active scientific colleagues in the 1980s but we both continued to develop Gaia in our own ways. My friendship with Lynn has grown with the years and it now includes my second wife Sandy, and embraces her own partner, the distinguished Catalan scientist, Ricardo Guerrero.
Well-disposed non-scientists seem
to think that science is founded on impeccable measurements and based in certainty. Scientists sometimes act upon this myth and become as dogmatic as are the religious. Remember Einstein’s famous denigration of the quantum theory, in a personal letter to Max Born, which is often summarized as: God does not play dice with the Universe. The radical French philosopher, Michel Foucault, said, ‘The truth is not discovered: it is something produced by the elite.’ He was talking of politics but his observation is true of science also. The truth at any time trickles down from the heights of the eminent. If senior biologists, respected by their peers, say life adapts to its environment, then this becomes the working dogma of biology. If senior geologists, similarly respected, say the presence of life is not needed to explain the evolution of the rocks, this also becomes a dogma. Together, these dogmatic beliefs become the conventional wisdom of science. It is in our nature to seek certainty. Because of their ‘faith’ in the conventional wisdom, most scientists rejected our life-detection experiments and Gaia theory when they were first proposed. They did so with that same certainty that the religious have when they reject the views of a rational atheist. They could not prove us wrong but they were sure in their hearts that we were. Lynn and I were astonished at what seemed to us a most unscientific attitude on the part of our peers, and by the scorn of their rejection. I was an innocent to expect Gaia’s acceptance, and truly foolish to imagine that such a radical theory could succeed in such an environment. It had as little chance of success as would a proponent of market capitalism have had in Lenin’s Russia.
The early 1970s were exciting yet frustrating. I read GE Hutchinson’s wonderful chapter called ‘The Biochemistry of the Earth’ in a book on the solar system and found that he came quite close to my own views about the Earth. He seemed to draw back from seeing it as self-regulating and went no further than to say it was an interesting chemical anomaly. Sometime during this period, I tried to have a talk with him during a brief visit to Yale University. There was also present at the meeting the geochemist, Jim Walker, who strongly, but in a friendly way, disagreed with my views, and did not hesitate to speak out against them. Both Hutchinson and I were somewhat quiet speakers and needed time to digest our exchanges. The threesome did not work and we achieved little. Sadly, I was never to have another opportunity of meeting Hutchinson before he died. I regret not reading Eugene Odum’s papers at this time for he alone understood that an ecosystem is a deterministic feedback system, which is how I saw Gaia: in many ways Gaia is the ecosystem of the Earth.
The first real stirrings of public interest in Gaia followed the publication of a paper written with my friend, Sidney Epton, of Shell. The title was ‘The quest for Gaia’ and it appeared in New Scientist in 1975. This paper did attract attention from the media. I received twenty-one letters and telegrams from publishers inviting me to write a book on Gaia. I chose Oxford University Press mainly because they sent a most personable representative, Peter Janson Smith, someone I liked and could easily work with. The book took four years to write and appeared in 1979. Its publication completely changed my life and the fall of mail through my letterbox increased from a gentle patter to a downpour, and has remained high ever since. To my astonishment, the main interest in Gaia came from the general public, from philosophers and from the religious. Only a third of the letters were from scientists. I never intended the book as a science text for specialists, but I did expect them to read it. I have always thought that science should be accessible to any intelligent person. Science affects our lives and that of the Earth so much that it would be monstrous for it to retreat to a world of jargon accessible only to the denizens of cosy ivory towers. I wrote the book as if it were a long letter about Gaia to a lively intelligent woman.
Geologists rejected the Gaia book gently, but biologists ridiculed it. Ford Doolittle was the first to do so. His article ‘Is Nature motherly?’ in the New Age journal, Co-Evolution Quarterly, argued that self-regulation by organisms required them to have foresight and to plan, which was impossible. Then Richard Dawkins argued against it in his book, The Extended Phenotype. His robust criticism observed that a living Earth could never have evolved by natural selection. How could planets compete with one another? It took me until December 1981 to find the answer to these criticisms and it was in the form of a mathematical model, which I called Daisyworld. I never intended Daisyworld to be more than a caricature, and accept that it may turn out a poor likeness when we finally understand the world. Even so, I still see it as my proudest invention and its main value is as Andrew Watson called it, a parable about Gaia and Earth System Science.
I populated my model world with two species of plant, dark-and light-coloured daisies; their world was well watered and had a simple climate uncomplicated by clouds or greenhouse gases. Daisyworld was in orbit around a star like the Sun, one that increased its flux of heat as it grew older. The model showed that the natural selection of daisy species growing on this planet led to the self-regulation of climate at a temperature near optimal for plant growth, despite large variations in heat from the star. When the star was young and cool, dark daisies covered the planet and, by absorbing sunlight, made it 17° C, warmer than it would have been without them. As the star warmed, the lighter daisies began to grow and compete, and their reflection of sunlight cooled the planet and kept the temperature optimal as the star increased its output of heat. Eventually, the star became so hot that even a total cover with light daisies was insufficient to prevent overheating and the system failed. It showed definitively that Ford Doolittle’s criticism that teleology would be required was wrong, as was Richard Dawkins’s criticism that planets would have to compete to select for self-regulation.
Daisyworld is much more than an answer to these criticisms; it shows how self-regulation could be a property of a planetary system and result from the tight coupling of biological and physical evolution. Daisyworld also provides a tractable working model of the phenomenon of emergence, and is an illustration of that wonderful state when the whole is more than the sum of its parts. I presented the first account of Daisyworld at a conference in the Netherlands in 1982 hosted by the Dutch scientist, Peter Westbroek. It appeared in the conference proceedings, but this kind of publication only establishes priority in a legal sense. Scientists now accept only peer-reviewed papers. I knew that Daisyworld needed publication in a proper journal. My problem was that I could not write mathematical papers in a way the referees would accept. I therefore asked my friend, Andrew Watson, if he would join with me as co-author. Andrew writes well and, unlike me, in a way that other scientists like. He is also an accomplished mathematician. He agreed and we prepared our Daisyworld paper. We tried Nature first, but that journal would not even consider sending it to referees. We then submitted it to Tellus, the journal that had published my second paper on Gaia, the one written with Lynn Margulis in 1974. Tellus published Daisyworld in 1983.
Daisyworld is a synopsis of Gaia Theory. It shows how organisms evolving under the rules of natural selection are part of a system that is self-regulating. Daisyworld keeps its temperature close to the optimum for daisy growth. There is no teleology or foresight in it. Neither is there, as our critics persist in saying, any built-in prejudice in favour of regulation. The persistence of this inept criticism so irritated me, especially since it came from prejudice, not from thought, that I made a simple variant of Daisyworld where, at the start, the organisms were all grey daisies. Grey daisies have no effect on global temperature. I then allowed them a small chance to mutate at random either to slightly darker than grey or to slightly lighter than grey. This chance mutation is what would happen in nature, and biologists would see it as adaptation. Not surprisingly, when this new model Daisyworld was cold, the daisies that mutated to slightly darker than grey had a better chance of survival because they were warmer. In a short time, mutation had moved the average daisy colour almost to black. This is similar to the change of skin colour when white-skinned people are exposed to a few thousand years of
tropical sun—the cumulative ill effects of sunburn reduces the family size of paler people. As Daisyworld warmed, so the average colour grew lighter, until at the hottest, it was close to white. This model was a better temperature regulator than the original Daisyworld. Tim Lenton has developed and expanded it. He demonstrated that adapting by mutation confers advantages not present in the original black-and-white Daisyworld.
Daisyworld can model the regulation of the chemical environment as well as the climate. In my book, The Ages of Gaia, written in the mid-1980s, are described models of bacterial ecosystems that simultaneously regulate climate, greenhouse gases, and oxygen. Daisyworld models are distinguished by their remarkable resilience and stability. Disasters can occur in the models that destroy up to eighty per cent of the organisms, but in spite of them, the system promptly recovers once the disaster is over. Stephan Harding, an ecologist working at the Schumacher College in Devon, has built complex ecosystems involving a wide range of food webs among plants, herbivores, and carnivores. He has taken advantage of Daisyworld’s stability to show how more complex food webs give rise to greater climatic and ecosystem stability, and how this comes about due to tight coupling between organisms and their global climate. Stephan is a biologist who trained in Oxford in the Department of Zoology and had as mentors such luminaries as Richard Dawkins and William Hamilton. Stephan has been instrumental in building bridges between Gaian scientists and the evolutionary biologists. He and his partner, Julia Ponsonby, have become firm friends and we walk and work together regularly.
Homage to Gaia Page 36