Introduction to Gaia


The GAIA principle

What is it?
It is a theory, just like any other theory in Science, a model of how something works.

What does it say?
That the earth is in some way "alive".

What is life?
The assemblage of abilities which make it possible for a living thing to maintain its existence. This includes taking in food, getting energy from it, keeping body temperature constant, keeping blood pressure steady…. Temperature and pressure are properties of collections of things. Our body contains organs and tissues. We are complex communities within ourselves. Life is social, it exists in communities inside and outside the body. Gaia is the community of all living things and their surroundings, including rocks and water.

How are rocks alive?
A tree is 99% dead wood, but the dead bit (trunk) is an essential part of the living entity.
In more detail. Ourselves and the whole of our surroundings are part of a living supersystem. The atmosphere, the oceans, the crust of the earth, the climate, are regulated in a state comfortable for life, because of the behaviour of living organisms in combination with what we have previously called the 'dead bits'.
More precisely: The temperature, oxidation states, acidity levels and other geological and hydrological conditions are kept constant, maintained by active feedback processes operated automatically and unconsciously by the Biota (the conventional living organisms).


The conditions are constant only in the short term, because they evolve to fit the changing needs of the biota as it evolves.

Why entertain the idea?
Because it explains the remarkable constancy of the properties of the oceans and the atmosphere over very long periods of time.
1. Constant atmosphere. In the atmosphere are Oxygen and Methane. Everywhere over the earth Oxygen is 20% and methane is 1.5 parts per million. But Oxygen and Methane react together as soon as they make contact. To maintain the present ratios, 1000 million tons of methane must be put into the atmosphere every year, and so must 2000 million tons of Oxygen. So just the right amounts must have been provided regularly for millions of years to keep the present biota going.
2. Salinity of Oceans. There is about 4% of salt in every ocean. If 6%, there would be no life, but it never reaches 6%.
3. Combustion. There is 20% Oxygen in the air. If there were 15%, no fire could ever be kept going; if 25%, no fire could ever be stopped.
4. Temperature. The temperatures in the temperate zones have been constant enough to support life for billions of years, although the sun now gives one third more heat than it did originally. The temperature has been kept from rising by gradually burying carbon to cut down the amount of carbon dioxide in the air because it retains heat through the 'greenhouse' effect.
There are many other feedback control effects now being elucidated.


So why don't we all accept it?
Many Scientists are unhappy because it threatens their familiar compartmented view of the world, for example, it blurs the distinction between Geology and Biology, so it threatens the entrenched specialist in either field.

Many other people are scared that life's maintenance of the conditions suitable for life smacks of a purpose in creation, whereas they prefer to disguise this by explaining life's development in terms of 'random' mutations and 'natural' selection.

Why does it matter to me?
Because Gaia is not just another theory. It says that since life started with the bacteria, it has controlled conditions so that humans can come into existence. Now we have attained self-consciousness, we have to decide whether we are going to collaborate with Gaia or not. If we do not, all life could collapse. So we can no longer pretend not to notice the moral dimension of our 'scientific' activities.

What and where are the problems?
1. Ozone layer. This is high up in the atmosphere, protecting against radiation from space. Some aerosols can rise that far and act as catalysts to destroy the layer. Only a few parts per billion are required. The effects are uncertain, but the current rate of change in the upper atmosphere is catastrophic compared with pre-industrial revolution.
2. Greenhouse effect. Carbon is extracted from the atmosphere as carbon dioxide and built into eg tree-trunks, buried when the tree dies. If we burn coal, ancient tree trunks, the carbon is returned to the atmosphere, which adds to the greenhouse heating effect. A one degree C rise in average temperature is enough to flood London and many other cities.
3. Rain forests. The forests pump up water into the air to produce clouds and rain over the whole earth. If the Brazilian forests are burned, we will have the equivalent of a Sahara desert there in 50 years, and a billion people without homes and food.

What could happen if we don't collaborate with Gaia?

There are two possibilities.
1. Gaia collapses, no environment control is exerted and conditions for life no longer exist.
2. Gaia will flip into some other stable state, which would support some type of life, but not humans.

The Gaia principle can provide a theoretical underpinning for all our environment activitiesand seems to provide a more satisfactory co-ordinated view of evolving life than before. It replaces 'survival of the fittest' with the need to collaborate.

Introductory References

Lovelock, James: (The originator of the Gaia concept).
Gaia: A New Look at Life on Earth
Paperback - 168 pages (28 September, 2000)
Oxford Paperbacks; ISBN: 0192862189

Margulis, Lynn, & Sagan, Dorian, What is Life,
303 pages, August 2000
The University of California Press; ISBN: 0-684-81087-5
Lynn has worked with Lovelock from the beginning of Gaia.

Volk, Tyler: Gaia's Body: Toward a Physiology of Earth. Paperback - 296 pages (1 May, 2003)
The MIT Press; ISBN: 0262720426

A wide-ranging introduction to Gaia theory is EARTHDANCE: Living Systems in Evolution, an Essay by Elisabet Sahtouris (1995)

A valuable short introduction is provided by David Orrell

More detail is provided at:

Origin of Gaia Theory

Daisy World models


Objections to Gaia