Is the Gaia hypothesis theory scientifically valid? Essay

Is the Gaia hypothesis theory scientifically valid?

According to the Gaia theory home page it is a new and exciting way of looking at the earth and means that is much more than just the third piece of rock form the sun. The Gaia hypothesis is one which claims that the earth and all it contains, living and non-living are part of one complex organism. It takes its name from the ancient Greek myth of the goddess of the earth who pulled it together out of the chaos. It puts the proposition that all living things have a part to play in regulating the whole. “Life maintains conditions suitable for its own survival.” according to the Gaia conference as reported on the Gaia theory Home page. If so this makes it tremendously important at a time when man seems bent upon interfering with it, such as the destruction of the rain forests. It seems obvious that if the balance is upset the whole earth will be put out of balance. It seems to us a modern idea, but something similar was put forward as a serious scientific theory as long ago as 1789 by a Doctor Black, the discoverer of carbon dioxide. He was giving a lecture in the name of the ill James Hutton, a geologist, who had written ‘I consider the earth to be a super-organism and that its proper study should be by physiology.’ Hutton was a farmer and believed that the forces that brought about changes on his land, as when a stream gradually formed a deep valley, were exactly the same forces that brought about changes to the Earth in the past. His key phrase was ‘the present is the key to the past.’ He called his idea uniformitarianism. The idea of Earth as one being is however much older. Plato said “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.”  He also said “ It has come into existence; for it is visible and tangible and possessed of a body; and all such things are sensible.”

This idea sees the earth as like our bodies which is made up of millions of cells that work together to maintain the whole. The earth according to this idea is made up of many millions of organisms which work together, consciously or unconsciously according to point of view, to maintain the balance and existence of the whole. The earth’s various systems are one gigantic ecosystem known as the biosphere. The earth’s four main components  – atmosphere, living beings, rocks and earth, and the waters, must work together just as the various parts of our bodies must work together. If we get hot we sweat, if cold we shiver and so on. This can be seen as being in opposition to the idea of a creation as an intact earth, but carried with it the idea of an evolving system and was quoted by James Lovelock in his Tokyo lecture of September 1992. Hutton’s ideas were not accepted at the time and little was heard of such ideas until the twentieth century. It is an idea mainly associated with Lovelock and his colleagues, but much earlier in1929 Russian scientist Vernadsky  said , long before space exploration:-

“Life appears as a great, permanent and continuous infringer on the chemical ‘dead-hardness’ of our planet’s surface … Life therefore is not an external and accidental development on the terrestrial surface. Rather, it is intimately related to the constitution of the Earth’s crust, forms part of its mechanism, and performs in this mechanism functions of paramount importance, without which it would not be able to exist.” )

Veradsky’s ideas did not  become part of worldwide scientific thought at the time, possibly because of language and political differences, but he was widely respected by those who could read his work. The Gaia idea of earth as a single, if complicated organism is easier for modern people to accept than it was two hundred years ago, or even in the time of Veradsky, because they have been exposed to the many pictures of the earth taken from space, in which it does indeed have at least the appearance of being one organism.

Various groups have since explored their idea from their own points of view. There are feminists for instance, who go with the idea of the Earth as the ultimate female. Politicians accept it in order to support various arguments with regard to such things as carbon footprints, but it must be admitted also to denigrate other political groups. There are those who use the theory to attack Christianity with its belief in a created world. Then there have been those who condemn it as a return to paganism, as on the web site Contender Ministries

Lovelock had studied with NASA the atmospheres of the planets Mars and Venus. He designed instruments to detect any possible life on those planets, which of course, if it existed at all, would almost certainly be very different from any life on earth. This caused him to consider carefully what constituted life. There seems to be no universally accepted definition of what constitutes life among the various factions of the scientific hierarchy and indeed in other groups, but according to Maturana and Varela in 1987 it is a process, an organisation and a set of relationships between its components. Lovelock came to the conclusion  that the differences between these planets and Earth could be explained by the presence of life here. Both these planets have an atmosphere containing about 95% carbon dioxide .Earth has 4.04 %. Venus has a similar size, gravity and makeup to Earth, but of course does not sustain life. It too has an atmosphere made up almost entirely by carbon dioxide. The Mariner 4 expedition, as reported on the web site ‘Mars Introduction’ came to the conclusion that Mars is self-sterilizing and that living organisms are prevented from forming. It now only has 1/100th of the water that earth has, but there seems to be evidence that it had much more in the past. However all chemical reactions that were possible there had already taken place long ago – the planet is now dead.

So what of Earth? Is it just a lump of rock spinning in space and acted upon by the organisms that live upon it and by physical forces such as earthquakes, sunlight and so on, or is it one huge living organism? The Gaia hypothesis claims that the earth, by regulating factors such as carbon dioxide levels, the amount of oxygen in the atmosphere and the quantity of salt dissolved in the oceans, maintains  an equilibrium. There are those who maintain that the seas and rivers are a kind of circulatory system and the atmosphere they liken to its respiratory system. In other words we, and all living creatures, are alive because the earth allows us to be. Those who accept the hypothesis point to the way in which oxygen levels have been maintained at 24% throughout the ages – the perfect level to maintain life. But the earth wasn’t always alive in this way – it must have begun as a molten mass, far too hot to allow life for millions of years. Molecular oxygen is a by product of photosynthesis. In other words it could only be present in the earth’s atmosphere as a result of life – bacteria in the beginning and eventually green plants. There is a long term balance between the production of oxygen and its use by living creatures and in other ways. It was this balancing act by oxygen molecules that is one of the main factors behind Lovelock’s Gaian ideas.

“For me, the personal revelation of Gaia came quite suddenly – like a flash of enlightenment. I was in a small room on the top floor of a building at the Jet Propulsion Laboratory in Pasadena, California. It was the autumn of 1965 … and I was talking with a colleague, Dian Hitchcock, about a paper we were preparing … It was at that moment that I glimpsed Gaia. An awesome thought came to me. The Earth’s atmosphere was an extraordinary and unstable mixture of gases, yet I knew that it was constant in composition over quite long periods of time. Could it be that life on Earth not only made the atmosphere, but also regulated it – keeping it at a constant composition, and at a level favourable for organisms? (1991)

                      Quoted by David Orrell, see Gaia theory.

The removal of carbon dioxide from the atmosphere is one of the regulatory systems that he was talking about. Carbon dioxide is removed from the atmosphere by the action of rocks weathering. This process is greatly accelerated if there are bacteria present. The carbons are washed away into the oceans where they are used by sea creatures to form shells. Eventually the creatures die and the shells fall to the bottom of the sea and form limestone. This is heavy and eventually falls so far that it melts in the heat of the earth’s core. Eons later it will emerge again when a volcano erupts. The soil bacteria are more prolific as well as more active in warmer temperatures and so more carbon dioxide is removed. This in its turn causes a cooling and so the cycle goes round. In pre-Cambrian times it was the activity of such bacteria that altered the dominant reducing environment and gave the Earth its present aerobic atmosphere and so enabled more complex life forms to develop.

 Another thing that those who agree with Lovelock point out is concerned with the salinity of the oceans. Salt runs off from the land into the sea, so logically levels should have risen and should continue to rise. But it stays at 3.5% – a fact for which  scientists haven’t yet come up with a satisfactory explanation, but if the level ever did rise above 4% cell life would be unable to function.

There are in fact 5 Gaia hypotheses:-

1 Influence – the belief that the living world has an impact upon the non-living part of it and that the planet’s temperature, for example, is controlled by the amount of life sustained as in the carbon dioxide cycle mentioned above. Each species pursues its own ends, but these combine to have a regulatory effect upon the whole.

2. Co-evolutionary Gaia – this states that while the living world has an influence upon the non-living the reverse is also true. In other words both life and the environment in which it exists are parts of one linked system.

3. Teleological argument – that is that the earth seems to have been specially made for the purpose of maintaining life.

4. Homeostasis  – the hypothesis that life on earth influences the lifeless part in a way that stabilises it.

5. The Optimizing theory – that Gaia creates somehow the most favourable conditions for life on earth i.e. does what is most likely to promote its own survival. Individual species manipulate their environment in order to produce conditions that are better or even optimal for their survival.

In 1974 Lewis Thomas ( 1913 to1993) wrote the book ‘The Lives of a Cell’. He gave it the subtitle ‘Notes of a Biology Watcher. In it he said :

I have been trying to think of the earth as a kind of organism, but it is no go. I cannot think of it this way. It is too big, too complex, with too many working parts lacking visible connections. The other night, driving through a hilly, wooded part of southern New England, I wondered about this. If not like an organism, what is it like, what is it most like? Then, satisfactorily for that moment, it came to me: it is most like a single cell.

This parallels the ideas that  Professor Lovelock had put forward in the nineteen sixties which came out of his work for NASA.concerned with the search for life on other planets. Lovelock defined Gaia as ‘a complex entity involving the Earth’s biosphere, atmosphere, oceans, and soil; the totality constituting a feedback or cybernetic system which seeks an optimal physical and chemical environment for life on this planet.’ This is sometimes referred to as geophysiology. Lovelock’s initial idea, which he has since modified, was that the biomass works together to make the earth more hospitable – a work that has continued to this day. The first statement of the hypothesis as put forward in the journal ‘Atmospheric Environment’ was: “Life regulates the climate and the chemical composition of the atmosphere at an optimum for itself.” This was seen by many as being a teleological argument i.e. a theological idea  that  the earth was created with this purpose. As such these opponents did not see it as a valid scientific argument. In 1979 his book ‘Gaia: a new look at life on earth.’ was published, the name Gaia being at the suggestiion of his neighbour William Golding. In it he describes the search for Gaia as the search for the largest living organism on earth. Ford Doolittle, a biochemist made a strong refuttal of Lovelock’s ideas in his article ‘Is nature really motherly?’and has has been quoted by Lovelock as saying that there is no way for organisms to be responsible for the regulation of such thing as climate without forethought , which is impossible. It is perhaps more realistic to thing of earth as a symbiotic unit than as a single organism. In this view evolution is a co-operative rather  than a competative idea as put forward by those who believe in the survival of the fittest.

Some feel that Lovelock’s idea  is not a valid proposition, but that it nevertheless has value because thinking about it has resulted in many experiments by a variety of experimenters. He has considered the points of view of various branches of science. Whether or not scientitsts accept any or all of the theories that come under the Gaia umbrella, they generally recognise that the concept is a useful way of considering the ways in which earth’s ecosystems are integrated and are affected by human activity. There are those who assert that if humanity does continue towards exceeding the limits of tolerence that the systems have e.g. by producing greenhouse gases, then the results will be catastropic and final. Others would say that ultimately the earth will always have feed back systems that will keep it in balance, but how does this fit in with what we see happening – greater warmth, fewer clouds and rising carbon dioxide levels? Lovelock states that life itself is this regulatory mechanism.Even if that is so  we still have the paradox of what is normal – the iceage or our present comparatively temperate climate? If the iceage is the norm the present situation can be compared to a fever. In 2006 Lovelock said in his article about his book‘the Revenge of Gaia’ ‘The earth is about to catch a morbid fever that may last as long as 100,000 years.’ In this article he puts the onus firmly on man , who, he says, because of their failure to recognise the self regulating abiliites of the earth , have tried to regulate it for themselves and so have unthinkingly worked towards the destruction of the system. Darwin, he says, was concerned with how organisms adjusted to their environment, but we what we need to be concerned with how the environment adjusts to living organisms. The Penguin site for his book describes him as a ‘planetery physician’. He has it seems at least helped to make the diagnosis, the first step in any treatment. However if Gaia represents the organisms that work together to make up the Earth, whether  or not we consider it as one macro –organism or not, when one part collapses all parts are affected. Richard Mabey, reviewing ‘The Revenge of Gaia’ describes his book as reading like the Book of Revelation.

 At present the Gaia ideas will remain as hypotheses, as they cannot be properly scientifically tested or measured against a similar planet with similar conditions and so be either proved or disproved. The scientific information necessary to prove the theory isn’t jus t available or obtainable. The only way that the theory could be possible completely tested would be by comparing earth to a very similar world, but non ehas so far been found. However the ideas are of value if they make us more aware of what is going on and make us consider our role as part of the whole makeup of the earth. The ideas involved offer the scientific community a new model to work on And so they are neither valid or invalid, but nevertheless important. They offer patterns for the future design of economic, social, agricultural and energy systems such as attempting to decrease greenhouse gases and everyone on earth aiming for a smaller carbon footprint. Whether or not these solutions will be effective only time will tell.




Lovelock,J. Gaia: a new look at life on earth Oxford University Press: Oxford, 1979 Lovelock, J. The Revenge of Gaia Penguin: London, 2006

Maturana, H.R. and Varela, F.J. The Tree of Knowledge Shambala: Boston, 1987

Thomas, L., The Lives of a Cell Viking Press: New York,1974

Vernadsky,V.I. La biosphere , Felix Alcan , 1929


Doolittle, F. ‘Is Nature Really Motherly?’ CoEvolutionary Quarterly, 1981

Lovelock,J. ‘Atmospheric environment ‘ 1974

Electronic Sources

Contender Ministries found 16th April 2007 at

The Evolving Gaia theory – a lecture at the U.N. University, 25th September 1992, Tokyo, found 16th April 2007 at

Gaia Theory Homepage found 30th April 2007 at

Lovelock, J. The revenge of Gaia,  found 16th April 2007 at

Mars found 16th April 2007 at

Mayby, R.reviewing ‘The Revenge of Gaia,’ Times on Line, found 16th April 2007 at

 Orrell, D. Gaia theory,  found 16th April 2007 at

Plato found 16th April 2007 at Orrell, D. Gaia theory,  found 16th April 2007 at