Gaia - Unity of life on earth.

Principles of scientific pantheism* by Paul Harrison.

Featured, Dec. 12, 1996.

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Gaia links together plants, animals, bacteria, rocks, oceans, and atmosphere in a unity that shapes the planet and maintains life on earth. We are one with the planet and with all life.

The mother of all life.

Scientists disagree about how life began - in space, in warm rock pools, in oceanic vents, on clays, and so on.

The evidence so far suggests that life on earth started as a single breakthrough cell after hundreds of millions of years of chemical evolution. This ancestor cell divided and diversified over the course of billions of years into the fantastic variety that we know today. We know they had a common origin, because all cells use the same type of RNA and DNA molecules for their genetic material - indeed a few genetic sequences are present in all living organisms.

"All the organic beings which have ever lived on this earth may be descended from some one primordial form," wrote Charles Darwin in The Origin of Species.

In a real sense all life on earth may be related as siblings, just as all humans appear to descend from a single family.

How earth and life moulded each other.

Life was shaped by its earthly environment - only organisms that were adapted survived. But once life got started, it shaped the planet in return.

Earth's original atmosphere was probably like that of Venus and Mars: more than 95 per cent carbon dioxide, with around 3 per cent nitrogen. There would have been traces of other gases, but no free oxygen. In this atmosphere only anaerobic bacteria could survive - ones that require no oxygen.

When the cyanobacteria - blue-green algae - emerged, they completely changed the earth's atmosphere. Using solar energy for photosynthesis, they consumed carbon dioxide, and pumped out oxygen. Eventually free oxygen began to accumulate in the atmosphere. The ozone layer, which shields life from damaging ultra-violet radiation, was formed.

The blue-green algae altered the planet far more drastically than we have done so far. Because of the continuing presence of life, Earth's atmosphere is now quite different from that of the other planets. It is 77 per cent nitrogen, 21 per cent oxygen, 1 per cent water vapour, and 1 per cent argon. Carbon dioxide makes up less than one two thousandth of one per cent.

Life even altered geology. Free oxygen combined with iron in the sea and on land, making iron oxides and other mineral deposits. The skeletal remains of sea creatures drifted down into sea-floor sediments and became chalk and limestone. Other organic remains became coal and oil.

The creation of Gaia

Life needed the right circumstances to get going - water, the right temperature range and so on. But once started, life maintained the conditions for its own survival.

Together life and non-life on earth created what James Lovelock has called Gaia, after the Greek goddess of earth.

At first the earth was hot, from the energy of the collisions that formed it. As the planet cooled, the earliest bacteria gave off carbon dioxide and methane. These acted as greenhouse gases, keeping temperatures high enough for life.

But then the sun gradually began to increase its output. The blue-green algae came to the rescue: they consumed carbon dioxide, and gave off oxygen. Carbon dioxide and methane levels in the atmosphere dropped, reducing the greenhouse effect, so the earth's temperature did not rise.

Life also kept the water it needed on earth. Hydrogen is a light gas which would have evaporated out to space without living processes to bind it, leaving a planet as arid as Mars.

Gaia links together plants, animals, bacteria, rocks, oceans, and atmosphere in a unity that shapes the planet and maintains life on earth. Even the major elements of life - carbon, oxygen, and nitrogen - pass in turn through air, plant and animal life, soil, water, and the earth's crust in cycles lasting hundreds of millions of years.

We are one with the planet and with all life.

Gaia - powerful but vulnerable.

Gaia can work marvels. She retains water on the planet. She counters varying output from the sun and keeps temperatures within the range that life can tolerate. She maintains a protective layer of ozone - but manages to keep oxygen below the danger level at which devastating fires would break out.

It's important not to get the wrong idea about Gaia. She is not a superorganism. There is no collective planetary mind coordinating everything towards a goal. Everything is the result of the laws of matter and of nature working through individual species in their environment. To recognize this is not to diminish life or Gaia, but to realize yet another aspect of the incredible richness of matter and nature.

Gaia is not a single organism but a community, a living, breathing community of all living beings evolving in harmony with their non-living environment. She is crafted, like a statue, by a mixture of creativity and discipline. As in evolution, the creativity comes from genetic mutation and sexual reproduction; the discipline comes from natural selection adapting organisms to their environment.

There are limits to Gaia's powers. She cannot keep at bay the chills and fevers of glacial and interglacial periods. She could not cope with a massive increase in the sun's size, which will happen when the sun becomes a red giant in a few billion years' time. She might not survive with a very massive meteoric impact or the explosion of a nearby supernova. She may not be able to endure the damage we are imposing on her.

And remember that Gaia shelters life in general - not any particular form of life. In the past 600 million years she has presided over five major mass extinctions which saw many major kinds of animals like dinosaurs and ammonites disappear. The Permian extinction wiped out 75 to 90 per cent of all species. But life went on, and the niches left by extinct species and families were filled by new ones.

Co-evolution and interdependence

Co-evolution, complexity and interdependence are key expressions of the unity of life.

Species do not evolve in isolation - they do so within their physical environment and the thousands of other species around them. Species usually evolve so that a maximum of life can exist in a given environment and every niche is filled. If two species have too close a niche, they evolve different characteristics so as to reduce competition between them.

Diversity and complexity are the outcome. But they do not lead to chaos. Instead evolution weaves the wealth of species into a web of interdependence. Herbivores eat plants. Predators eat herbivores and each other. Plants and animals die. Decomposers recycle their bodies into soil. Soil feeds plants. And so on in self-sustaining cycles.

Species in the same habitat evolve together to create ecosystems in which all parts work together through complex cycles and balances. This interdependence means internal stability over time: normally no single species can run riot and disrupt the whole system.

But interdependence also means vulnerability. If outside forces alter one element of the system, then all the elements may be put at risk.

Some pairs of species evolve into much closer relationships. These included predators and prey, parasites and hosts, symbionts like fungi and algae in lichen, mimics and their subjects, flowering plants and the animals that pollinate them and disperse their seeds.

These closely co-ordinated partners are very vulnerable. If one of a set becomes extinct, the others may well do so too.

Co-evolution and interdependence in nature do not mean conscious co- operation. Species compete with each other, eat each other as usual: their apparent cooperation is due to natural selection. But the self-regulation of the whole eco-system ensures that they benefit each other.

Gaia's dysfunctional brain: humanity.

Gaia functioned well as long as she functioned automatically. She had no mind, no planetary brain. She worked by the creativity of matter and life weaving webs of interdependence.

It was when she acquired a brain, in the shape of human intelligence and technology, that things began to go wrong.

Humans don't have the science or wisdom to control Gaia. But we do have science and technology powerful enough to inflict serious damage on her. Already we are making a disturbing impact on most local ecosystems, and on three of Gaia's four major zones: the biosphere, the hydrosphere and the atmosphere. In the long term what we are doing will also feed through to the lithosphere and alter earth's geology.

So we are not Gaia's mind in any wonderful, mystical sense. We are not guiding her on to new heights she could never reach without us. We are a very dysfunctional sort of mind. Like the mind of a heavy drinker, drug-abuser, smoker and glutton, we harm ourselves and our "body," Gaia, by over-consuming and polluting.

Undermining the Gaia mechanism.

Ever since the invention of agriculture we have been destroying local ecosystems and destroying biodiversity.

But it is only in the twentieth century that we have begun to interfere in some of the most basic elements of the Gaia process.

About half a century ago we began using chlorofluorocarbons, chemicals that were thought totally harmless. It was only in 1985 that we discovered they were destroying the protective ozone layer. This is increasing human skin cancer. It may be reducing the yield of crops. It may reduce the growth of plankton, and through that affect oceanic processes.

Even more dramatically we are disrupting Gaia's mechanisms for temperature control - especially the levels of carbon dioxide and methane in the atmosphere. Coal and oil were formed from plant remains millions of years ago. By mining and burning them as our main energy source, we are increasing carbon dioxide in the atmosphere, from a pre-industrial level of 280 parts per million to 360 ppm in 1995.

Our 1,300 million cattle, our 250 million hectares of irrigated fields, and our countless rubbish heaps have more than doubled methane in the atmosphere from a natural level of 700 parts per billion, to 1,666 ppb in 1994.

Projections by the Intergovernmental Panel on Climate Change suggest that global temperatures may rise between 1C and 4C by the end of the next century on present trends. This change will raise sea levels. It will shift ecological zones, change rainfall patterns, and produce massive disruptions in agriculture.

As always, Gaia will do her best to cope. Even at worst, life in some lowly form will probably pull through. But many plant and animal species, unable to move fast enough, will die out. We may be one of them.

Getting back to unity.

We were not always a disease of Gaia: once we were an integrated part.
And we can be so again, if we have the will.

Gaia's mind: how we became separated from unity.
Gaia's children: how we can return to unity.

This page is based primarily on the following source works:

James Lovelock, Gaia, Gaia Books, London, 1991.
Douglas Futuyma, Evolutionary Biology, Sinauer Books, 1986.
D. Futuyma and M. Slatkin (eds), Co-evolution, Sinauer Books, 1983.
Robert Ricklefs, Ecology, Third Edition, W. H. Freeman, New York, 1990.
Richard Cowen, The History of Life, Blackwell, Oxford, 1990.
Image of Gaia's edge courtesy of Tim Lynch.

Gaia links

The Gaia hypothesis: scientific background on Gaia.
GaiaMind: sign on for collective meditation about Gaia. Remember the effect can only work by affecting your behaviour.
Ourplanet - Gaia from a New Age perspective.


is the belief that the universe and nature are divine.
It fuses religion and science, and concern for humans with concern for nature.
It provides the most realistic concept of life after death,
and the most solid basis for environmental ethics.
It is a religion that requires no faith other than common sense,
no revelation other than open eyes and a mind open to evidence,
no guru other than your own self.
For an outline, see Basic principles of scientific pantheism. Top.

Scientific pantheism: index.
History of pantheism.
Basic principles of scientific pantheism.
Join the World Pantheist Movement

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© Paul Harrison 1997.