by Noel Charlton

from Institute for Environment, Philosophy & Public Policy Website

James Lovelock has developed the "Gaia Theory" over the last twenty-five years as a scientific claim that the earth’s "biota", tightly coupled with its environment, acts (and has acted since life on earth developed any complexity) as a single, self regulating living system in such a way as to maintain the conditions that are suitable for life. The system includes the near-surface rocks and atmosphere. In particular, it regulates the chemistry of the oceans, composition of the atmosphere and surface temperature.

More about the theory
Lovelock was working with NASA in the 1960s as a consultant to the "life on Mars" Viking spacecraft project. Questions about whether Martian life, if any, might be in any way comparable to life on earth, about how life can be recognized, indeed, about what life is, led him to see that a reduction or reversal of entropy in a planet’s systems would necessarily be a sign of life. In particular, the atmosphere of a planet with life would be different from that of a dead planet. The consequent reassessment of earth’s own atmosphere revealed it to be a "highly improbable" mixture of gases which could only be maintained if it was "manipulated on a day-to-day basis" by life on the surface. And so the hypothesis was born.

Lovelock tells the story of how the Gaia hypothesis was named. Walking with novelist neighbor William Golding, he explained his excitement about the idea. Golding, thinking of the ancient Greek earth-mother goddess and of her dual character of caring supporter of beings who "fit" and ruthless annihilator of those who do not, suggested the name. Lovelock heard Golding as saying "gyre" and, thinking of cyclical weather-systems or the behavior of circling birds, thought it was not a bad idea. The two continued at cross purposes until Golding said:

"I don’t know what the blazes you’re talking about, Jim….". As Lovelock said (Schumacher College, 1996) "It has caused quite a lot of misunderstanding but you don’t turn down a gift like that from a wordsmith like Golding."

The Gaia theory suggests that, in some sense, the earth is "alive". Lovelock writes:

"I recognize that to view the Earth as if it were alive is just a convenient, but different, way of organizing the facts of the Earth. I am of course prejudiced in favor of Gaia and have filled my life for the past twenty-five years with the thought that Earth may be alive: not as the ancients saw her—a sentient Goddess with a purpose and foresight—but alive like a tree. A tree that quietly exists, never moving except to sway in the wind, yet endlessly conversing with the sunlight and the soil. Using sunlight and water and nutrient minerals to grow and change. But all done so imperceptibly, that to me the old oak tree on the green is the same as it was when I was a child."

(in "Gaia: The Practical Science of Planetary Medicine", Gaia Books Limited, London, 1991, p.12.)

The idea of a living earth is ancient. Plato wrote:

"We shall affirm that the cosmos, more than anything else, resembles most closely that living Creature of which all other living creatures, severally or genetically, are portion; a living creature which is fairest of all and in ways most perfect."

Gaia, goddess and earth mother, the Anima Mundi - the "world soul", the idea of "spirit" in things - we have only lost this understanding since Descartes and the coming of objective science. There were some advocates of a living earth even in the scientific period: James Hutton (earth as a super-organism, a physiological system), Lamark, Goethe, Humbolt and the (little known until recently) Russian scientist Vladimir Vernadsky who introduced the concept of the biosphere, recognized matter as "living", life as "a geological force" and the atmosphere as an extension of life.

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Evidence and an example
Lovelock claims that there is strong evidence to suggest an overall systemic control of the earth’s,

  • surface temperature

  • atmospheric composition

  • ocean salinity

The processes are complex and the following notes are simplistic reductions.


there has been a 25% increase in heat from the sun since life began but surface temperature has remained approximately constant.


the present highly unstable mixture of reactive gases (79% nitrogen, 20.7% oxygen, 0.03% carbon dioxide with traces of methane and other gases) could not be maintained without constant replacement or removal by the biota. The early earth had an atmosphere with more carbon dioxide and, at that stage, the consequent greenhouse effect warmed the earth beneficially. Subsequent increase of methane, then oxygen - all produced by biota and cycled through oceans and rocks has been maintained by evolving species. Now carbon dioxide is minimized in the atmosphere by biological pumping down of carbon. Without greenhouse gases our present surface temperature would be about minus 19C.

Ocean salinity:

has been maintained at about 3.4% for billions of years. Cells cannot tolerate salt concentrations much above 5%. Salinity is at least partly controlled by evaporate beds/lagoons where marine life causes limestone deposits, later buried. This process may be involved in initiating the movement of tectonic plates with consequent removal of salts to land masses.

One example of the complex processes which Lovelock sees as maintaining conditions suitable for life is that involving the Coccolithophores. These and other ocean algae are key agents in the great cycle of carbon from its introduction to the atmosphere by volcanoes, the weathering of limestone rocks accelerated by biotic life in the soil (which also draws down carbon from the air), the combination of these as calcium bicarbonate which, washed into the oceans, is used by algae to form shells which eventually fall to the sea floor to be buried, so locking away the excessive carbon dioxide. Additionally the Coccolithophores release a gas (DMS) which is important in forming the condensation nuclei around which clouds form. Increased cloud cover reflects sunlight, so controlling surface temperature. There is some evidence that concentrations of ocean algal blooms are increasing. This may be a Gaian response to the present global warming.

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The Gaia Theory has been attacked, particularly by neo-Darwinist thinkers W. Ford Doolittle and Richard Dawkins. They challenge Lovelock to show how organisms could produce concerted action, arguing that there is no way that natural selection could lead to altruism on a global scale. This, they argue, would require foresight and planning on the part of the organisms, such ability would need to be built into their genetic structure. They find it impossible to see how the feedback loops which Lovelock says stabilize the Gaian system could have evolved. They argue that, as Gaia can’t reproduce herself, she cannot be alive in any meaningful sense. They also claim that the theory is not scientific because it is impossible to test it by controlled experiment. Lovelock offered The Daisyworld model as mathematical evidence to refute most of these criticisms.

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The Daisyworld model
Daisyworld is a computer model of a hypothetical planet with characteristics similar to Earth including a rising input of solar heat. On its surface are, evenly scattered, the seeds of only two species: black daisies and white daisies. Early in the life of the planet conditions are cool; only at the equator is it warm enough for seeds to germinate and there the black daisies have the advantage as they more readily absorb what heat there is. As solar input rises the black daisies spread away from the equator and white ones gain a hold in the increasing warmth. When heat increases to the point where black daisies are overheated they can survive only near the poles, the rest of the surface being covered by the highly reflective white daisies. Surface temperature is initially increased by the absorptive black daisies, then stabilized for a long period by increasing concentrations of the heat reflecting whites. Eventually the increasing solar heat is too much for even the whites; these die and the planet becomes too hot for life.

Lovelock points out that, in this model, the effects beneficial to life are obtained by means of natural selection only - there is no need for purpose, altruism, teleology or anything beyond normal genetic process. In subsequent models grey daisies, herbivores and their predators have been added. These have proved more stable than other models that do not take environmental feedback into account.

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Philosophical implications
Gaian theory inevitably raises the issues of "teleology": whether non-human beings, ecosystems or genetic and evolutionary processes can have any sort of "purpose" and what that means. Lovelock claims that his theory demands responsiveness in the system(s) but not awareness, foresight or intention. The action of organisms is always automatic but natural selection "chooses" those that are fitted for the conditions - as in Daisyworld. Questions, however, remain. Why, for instance, should the needs of coccolithophores be exactly what will serve to take CO2[NGC1] (excessive for other planetary life) out of the atmosphere? If the system is in control, does this gives ontological status to the system itself? Is the whole system somehow able to value the continuance of "life"?

In Lovelock’s view humanity is peripheral, though dangerous, to the life systems of the planet. Our anthropocentric concern is to preserve the earth as we want it. Lovelock believes that ideas of stewardship of the planet are absurd and dangerous "hubris": "We’ll never know enough…….. The answer is ’hands off". The large plants and animals are the icing on the cake; the basis of life - what matters for a living planet - is the microbiological. Micro-organisms drive the system and we cannot influence them. We are probably incapable of destroying life on Earth. We can refrain from doing what we see is damaging but little more. This raises profound questions about responsible action for individual humans and social groups. Is value related to the continuance of life in general, to the experience of humans or of sentient animals? Why does it matter if species are destroyed?

Gaian thinking suggests an alternative to the view that the world is mechanistic, best understood by reducing everything to "parts", that life has come about by chance operation of the laws of physics and chemistry, that evolution is a matter of ruthless competition and that the natural world is there to be exploited. The new view shows the living world as interconnected, in some sense meaningful. What follows from instituting a new metaphor for the old "world as machine" one? David Abrahm’s paper in "Gaia in Action" (see reading list at bottom) suggests that the change to an organic metaphor removes the assumption of an external "maker" who is in some way like a human creator of machines. This undermines our assumption that we can treat nature as a machine and allows recovery of our sense of being encompassed by and immersed in the world as participants. In his introduction to the same book, Peter Bunyard suggests that the Gaian world has more to do with co-operation than competition, with integration of organisms and environment rather than struggle and competition. This provides, he says, fertile metaphors for community. Lancaster’s own Kate Rawles follows this with a paper which asks what ethics follow from the Gaian view.

  • Does it imply that ethical concern extends beyond humans to other sentient beings?

  • To ecosystems?

  • To the planet?

  • What sort of obligations and responsibilities could this meaningfully involve?

  • Does Gaia theory suggest that there are specifically environmental goals and values?

  • Does it tell us how we ought to act?

  • Does it depose humans from their assumed position at the "apex of evolution" and, if so, what follows?

There are further implications. The Gaian view may make it possible for humans to see themselves as significant (because conscious and self-reflexive) parts of a symphonic interaction. Could the whole earth as a single life preserving system command our respect, awe, even reverence? Could an understanding of Gaia become the focus for attitudes we have called "religious", thus influencing change in human impact on the planetary process? Lovelock has written

"For me, Gaia is a religious as well as a scientific concept, and in both spheres it is manageable… God and Gaia, theology and science, even physics and biology are not separate but a single way of thought".

("The Ages of Gaia", pp. 206, 212. See reading list below.)

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Reading list

  • Bunyard, Peter (ed.),

    "Gaia in Action: Science of the Living Earth", Floris Books, Edinburgh, 1996. The most recent anthology of Gaian writing including contributions by Lovelock, Lynn Margulis, Brian Goodwin, Elisabet Sartouris and Kate Rawles.

  • Lovelock, J. E.
    "Gaia: a New Look at Life on Earth", OUP, Oxford, 1979. New edition with updated Preface, 1987.
    "The Ages of Gaia: A Biography of our Living Earth", OUP, Oxford, 1988. New edition, 1996.
    "Gaia: The Practical Science of Planetary Medicine", Gaia Books Ltd., London, 1991. (In USA: "Healing Gaia: Practical Medicine for the Planet", Harmony, New York. 1991.)

  • Margulis, Lynn, & Sagan, Dorian,

    "What is Life", Simon & Schuster, New York, 1995.

  • The computer "game" Sim Earth (Maxis Inc.) provides entertaining opportunities to play with the Daisyworld concept and more complex evolutionary scenarios.

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