In 1972, James Lovelock and his co-worker Lynn Margulis introduced a hypothesis regarding the earth as a living superorganism. This hypothesis was later given the name of Gaia by the Nobel literature prize- winner William Golding, who recognized the parallel between the mother earth of Greek mythology and Lovelock’s idea. A further development of the hypothesis was presented in Lovelock’s books Gaia: A New Look at Life on Earth (1979) and The Ages of Gaia (1988). As a well-known and ethically neutral hypothesis it has, however, been more neglected rather than criticized by the scientific community.
The hypothesis of Gaia is a contemporary expression of ancient wisdom concerning nature. The conception that the earth is ‘living’ is probably as old as humanity itself. Many cultures and religions, and speculators, since Aristotle had their convictions about the existence of a harmonious order in nature. The physician and alchemist Paracelsus (1493-1541) regarded nature as a complex organism in contact with an investigator. The Scot James Hutton (1726-1797) wrote in 1788, in his book Theory of the Earth, about the restoring and healing forces of nature. In his lectures he is reported to have stated: ‘I consider the earth to be a superorganism and that its proper study should be physiology.’ In line with his predecessors, Lovelock has introduced the term geophysiology. This term stands for a systems approach to biospheric life analogous to the physiological study of an organism.
At the heart of the Gaia hypothesis is the fact that life creates its own milieu — something Lovelock became aware of when he realized that the chemistry of atmosphere offend against laws of chemical equilibrium. Existing qualities of the atmosphere, oceans and continents are not prerequisites for life, they are instead consequences of life. Life influences the milieu in an extraordinary way, not possible for ordinary physical/chemical forces. Life has taken control of the whole earth and transformed a lifeless planet into a self-regulating, self-sustaining organism. During it, life has demonstrated itself as an all- or-nothing phenomenon. Life existing on certain parts of the earth only is a contradiction of terms like a living, half, animal. Furthermore, life is immortal. Once established, it cannot be eradicated. It can be extinct in one place or planet but will always continue to exist in other locations. Life is a kind of network which is always plural and extended through space and time with the capacity to infiltrate all matter. Nowhere a solo living organism is to be find. It is an individual property only for a short fleeting moment. This organism continuously adapts the planet’s physical, chemical and biological processes to maintain optimal conditions for the development of life. It does not strive to adapt to a changing environment.
Life and its environment are so closely coupled that evolution per se concerns Gaia, not the organism or the environment taken separately. They should be seen as one single system. The dead basis of Gaia, the mountains, the deserts, the oceans and the ice surrounding the poles are an integrated part of Gaia. The biologist Jerome Rothstein reminds us, in a very useful analogy, how the old Redwood trees (Sequoia Gigantea) are built up. These trees remain of the structure of Gaia as 97 per cent of their tissue lacks life. Only a small shallow part along the stem can be considered living. The stem resembles the earth’s litosphere with a thin layer of living organisms spread out over its surface. The barque resembles the atmosphere, protecting the living tissue, allowing the exchange of biological important gases like carbon dioxide and oxygen. Even if something is considered dead, the wholeness thus can be considered living.
The emergence of photosynthesis created an atmosphere in which countless new species could evolve. Photosynthesis itself could only provide enough energy for a vegetative existence, but with the emerging oxygen metabolism animals could generate the power they needed for movement and activity. Nevertheless, the main system of Gaia are the plants. All the non-plant members of the biosphere are, by definition, reduced to supporting roles. The specific forms of life were all carriers of functions of the wholeness, following the principle that the most varied ecosystems are the most robust. Climate in turn has been dramatically affected by the presence of life.
Many ingredients vital to the function of the earth’s atmosphere have been produced by the biosphere itself, such as oxygen which has a central position in the interpretation of the Gaia hypothesis. Air is not just an environment for life but rather a part of life itself. One per cent rise in oxygen increases the probability of fire by 60 per cent. In one sense, the atmosphere is an artefact, like the honey or wax of a beehive, but atmospheric oxygen might also be thought of as a bloodstream connecting the various parts of the Gaia organism. The same can be said about soil, created in co-operation between geosphere, atmosphere, hydrosphere and biosphere and being the very basis for all kind of life. Soil provides the necessities of life like shelter, food, water and may be considered Gaia’s ultimate interface. See Figure 3.10.
Soil is formed by a combination of processes where physical weathering involves the fragmentation of rocks; where chemical weathering involves the alteration of the minerals that make up the rocks. The decomposition of plant and animal residues deposited on and in the soil and the movement by percolating water of suspended solids and dissolved materials down through the soil, also consitute this process. The processes of life thus co-operate to transform the planet into a safer place for life itself.
While other planets of our solar system are either extremely hot (Venus) or extremely cold (Mars), the earth has been successful in regulating its surface temperature for several billion years. It is estimated that the sun is between 30 and 50 per cent hotter now than when life began 3.5 billion years ago. In spite of this increasing heat radiation, the surface temperature has been maintained within limits favourable for life.
Lovelock claims that the continued existence of life per se is therefore not a question of adjusting to a warmer environment; it is a question of maintaining the status quo through control of the environment. Symbiosis, and the reciprocal actions between organisms and the environment, is seen as the source of evolutionary novelty and the chief agent of natural selection. The example par excellence is that plants absorb carbon dioxide and exhale oxygen, while animals do the reverse. Even altruism or purposeful intent is expected to play a role. The Gaia phenomenon is a collective property of the growth, activities and death of the innumerable populations that compose the biomass.
This contradicts the conventional evolutionary paradigm which asserts that life adjusts to the environment and sees the accumulation of chance mutations as the mainspring of development. The Gaia hypothesis in fact predicts that systems of this kind may arise automatically out of a mindless striving for survival. It adds, however, that life must be planetwide and powerful if it is to be present at all.
Lovelock states that biological control mechanisms always intervene when the earth grows too warm, too cold, too dry, too moist, etc. The various processes of life co-operate and regulate the global climate in order to create suitable conditions for life itself. Certain significant organisms can function on several levels and influence both the biomass, geology and chemistry of the earth. Their presence can alter land surfaces, water surfaces, albedo of clouds or act as nucleating agents for condensation. The chemistry of soil, water and air can be changed and thereby the distribution and transport of material may be changed. All parts of Gaia are interlocked through a series of complex feedback loops.
To illustrate the working principles of a global control mechanism Lovelock has constructed a computer model called Daisyworld. It is a hypothetical ecosystem consisting of black and white flowers. The black flowers thrive in a cold climate but, by acting as solar collectors, they induce heating. The white flowers thrive in a hot climate but reflect the sunshine and grow more numerous, thereby inducing a colder climate. Together these flowers can, without having an internal purpose, stabilize the temperature even if the incoming radiation increases.
According to the law of requisite variety (see p. 100), to maintain stability a system must have at its disposal a sufficient number of regulatory mechanisms. The following are some examples of such regulatory and protecting global homeostasis mechanisms, where life serves as an active control system.
- When solar radiation increases, the oceans grow hotter. The water volume expands and its level Nutritious substances from coastal areas are released into the water. With the consequent increase of plankton, dimethylsulfide accumulates in the oceans and evaporates into the atmosphere. Through this process the density of the heat-reflecting cloud cover is controlled and the temperature is held within a range of +5° to +35°C, the optimum for life. At the same time the growing amount of plankton absorbs the atmospheric carbon dioxide, decreasing the greenhouse effect.
- Seasonal variations of the atmospheric carbon dioxide content are dependent upon the foliage of plants. In the summer the green foliage absorbs carbon dioxide; in the winter it is emitted by the decomposition process on the ground. This is a predominant climate regulator in the northern hemisphere with its greater land mass.
- An ozone layer in the upper atmosphere protects all kinds of life from devastating ultraviolet radiation from the sun. This layer has possibly been created by oxygen originating mainly from algae, themselves sheltered from radiation by the ocean water. Tropical rainforests control the circulation of water. The vast forests of the Amazon account for more than half of their own water circulation, that is, precipitation, outflow and evaporation. Devastation of these forests would result in huge amounts of water leaving the region and a global climate change (the tropical rainforests act as a global air-condition!). The rain produced by the forest is in itself vital; normally containing small amounts of ammonia it supplies acid to the soil for optimal vegetation. Lichen colonize inhospitable mountain and cliff surfaces and assist in their decomposition. Decomposition products form topsoil, a prerequisite for the life of other plants. The composition of the atmosphere is also influenced by this process.
- The maintenance of an average salinity of 3.4 per cent is essential for life in ocean water. While a concentration of four per cent would have produced quite different life forms, six per cent would make life in water impossible. Salts released by weathering should long ago have made the water too salty for life. It is assumed that excess salt is neutralized by the corals that build reefs, in turn forming lagoons wherein large quantities of salts are trapped as the seawater evaporates. Salt, together with other minerals, also provide raw materials for sheaths where bacteria live.
- The sudden drop in both carbon dioxide and temperature a billion years ago chilled the upper mantle. This in turn might have destabilized the lower crust causing the continental drift. Ongoing life processes may also drive geological plate tectonics necessary for the renewal of the earth surface.
- Major grass and forest fires may act as regulators, keeping the oxygen concentration in the atmosphere at an average of 21 per cent. Above an upper threshold of 25 per cent fires would destroy the
- Volcanos are an important regulatory mechanism of the world’s Their eruptions eject enormous quantities of sulphur aerosol particles into the stratosphere, effective at reflecting solar radiation back into space, thus cooling the atmosphere. Volcanic eruptions, in their turn, seem to have direct connections with the rise or fall of sea level. Intensive coastal volcanic activity had been established when sea levels were rising rapidly, e.g. in the final stage of the last ice age when the ice was melting down to water. Rising sea level, however, seems to have the opposite effect when it regards island volcanos. Because such volcanos are completely surrounded by water, rising sea level actually increases the confining pressures, thereby reducing the ability of magma to reach the surface. Similar numbers of coastal and island volcanos give the effect that one type of eruption will offset the other, keeping the total constant. The conclusion is that rising sea level, by increasing volcanic activity, can help to counteract warming. For the same reason, falling sea levels can also exacerbate cooling.
The Gaia hypothesis postulates that the earth is a living organism an enormous, complex and self-regulating web of life capable of influencing and regulating her environment. It gives us a perspicuous conception how a high-complexity feedback system can maintain stable conditions also during drastic external disruptions. All living matter on earth, from virus to whale, from algae to tree, is regarded as constituting a single living entity. Gaia cannot be separated from the different parts of her body. The circulation of water from sea to land to sea is her flow of blood; her atmosphere is both the cuticle regulating temperature and moisture within her body and a protection against dangerous cosmic radiation from This tight coupling between life and environment and the constant preparedness for change and to adapt suggests distinctly different types of interactions, qualifying Gaia as a planetary superorganism.
Like other organisms Gaia has her life-cycle. Childhood implies a series of major changes alternating with long periods of relative little transformation. In adulthood the presence of life becomes the dominant quality of the planet. The niches are filled and the resistance to change is at its maximum. Inevitable old age is reached probably with the loss of internal heating and atmosphere. The parent star, the sun, reaches its Red Giant phase and Gaia is consumed by the expanding shell.
Lovelock’s train of thought can be further clarified if Gaia is seen as a ninth level of the GLS theory, albeit of a slightly different logical type (Gaia existed before the emergence of the cell and is in a sense a zero level). The 20 essential subsystems of Gaia according to Miller’s GLS theory can be identified as follows.
With a growing population, human activities within the global ecosystem are ever increasing, converting natural ecosystems to self life- supporting systems. What some scientists call the ‘The Greenhouse Civilization’ has tampered with the planetary cycles of energy and materials. Agriculture, forest logging, industrialization and urbanization are devastating land uses which bring about extensive pollution of land, air and water. By converting natural negative feedback to unnatural positive feedback, human civilization has interfered with and blocked some of Gaia’s control systems.
Gaia has thus been deprived of vitally important control systems and the preferences of the Greenhouse Civilization do not coincide with Gaia’s. For example, Gaia’s preferred temperature and ours are not the same. Interglacial periods like the present one, although existing for ten thousand years, may prove to be a global fever and the ice age may be the more stable state. The greenhouse effect itself is sometimes compared with a global fever used by Gaia to drive out devastating parasites.
Destructive activities of humans have also caused great damage to biodiversity. Loss of biodiversity by an accelerating extinction of all kinds of species is a devastating threat to the robustness of all the regulatory systems of Gaia. Furthermore, it will fundamentally and irreparably restrict our total understanding of Gaia as our planetary home.
The role of human beings in the Gaia system is, however, controversial among geophysiologists. Lovelock himself has a very cool attitude to humanity and its significance for Gaia; he views human civilization as largely irrelevant. He would sooner expect a goat to succed as a gardener than expect humans to become stewards of the earth. We are neither owner nor preserver of the planet but are solely one species among others. Nature survives without man — man on the other hand cannot survive without nature. If the human race will be exterminated by natural disasters (or by herself) the earth will reach homeostasis again (compare with the disappearance of the dinosaurs). She does this by giving birth to a new form of life that can manage the new living conditions. In the history of Earth complex life forms evolved 500 million years ago. Then the biota collapsed five times in mass extinctions involving more than 95 per cent of existing species. After each extinction the biota recovered in diversity, usually with different species on the stage but with the pattern of interaction remaining the same.
Gaia therefore can be seen as fragile in that the biosphere can be the victim of biospheric collapse through severe perturbations. It is, however, resilient because recovery is always fast and complete. This procedure can, however, take hundreds of thousands of years. Typical is the transition of the early ammonia-based atmosphere into an oxygen- based system which implied a deadly threat to the existing anaerobic organisms. These should have been extinct due to the increasing oxygen content. Instead some of them suvived by emigration to new environments (without oxygen) like marsh- bottoms, rivers-bottoms etc. Today, several million of years later, we find them in a safe and comfortable environment like the bowels of animal and man.
As a dynamic system, Gaia will always regain her balance but with no special preference for any particular life form. Contrary to popular quasi- philosophical movements like New Age which readily use the Gaia concept for their own purposes, Lovelock has no intention to put man and his well-being in centre.
In comparison with earlier global catastrophes, the Greenhouse Civilization leaves only a small scar in Gaia’s skin. It seems unlikely that human activities can threaten the life of Gaia but very likely that her response to our destruction is not to our advantage. If we choose to break the rules of life, Gaia will exterminate us. In other words, humanity will not destroy Gaia, Gaia will destroy humanity. Gaia, as any living organism, cannot remain passive in the presence of threats to her existence and she will always be the stronger party.
Some scientists, standing outside of mainstream science, assert that Gaia maintains optimal conditions for life according to a purpose and thereby displays some kind of intelligence. Although life is fundamentally self-organizing and self-determined we do not know its final goal. We, as components of the superorganism Gaia, cannot (from without) study her ultimate goal (the cell sees a very limited part of the inside of the body!).
Other scientists state that the analogy of Earth with an organism is false. In contrast to other complex organisms, the ecological system of Gaia lacks central information processing. Another reason is that the planet is not the product of evolution like a true organism and that it does not reproduce. Furthermore, Darwinian natural selection cannot be applied to a quasi-immortal entity like Gaia. Also, Gaia as an ecological system has no purpose of its own. Earth’s biota nurtures its own existence, but only in a non-purposeful way. However, it contains social and organismic systems that do, and deterministic systems that do not. The purpose of an ecological system is to serve its parts.
Gaia has nevertheless acquired a goal with the emergence of the human mind; through human beings, a central nervous system developed giving knowledge about herself and the rest of the universe. The capability to anticipate and neutralize threats to life itself has thereby been considerably augmented. Regarding Gaia’s reproduction, life is a planetary scale phenomenon. With this scale, it is practically immortal and has no need to reproduce.
Seen through the eyes of Teilhard de Chardin (see p. 152), the ultimate goal of Gaia should be the creation of a noosphere, Gaia’s thinking layer and the equivalent of the human neocortex. A human brain has at least 1012 neurons interconnected at 1014 junctions or synapses. Zoologists are of the opinion that a critical mass in brain volume is achieved at 1010 neurons, a level occurring in higher primates. This has an equivalent in the number of stars in our own galaxy which also is estimated to 1010. If therefore each human being is regarded as a neuron in the brain of Gaia, and given that the world population will soon reach 1010, a new kind of global consciousness might emerge. This new mental quality would not be the property of particular individuals; it would be manifested on a global level.
The interconnections between the neurons create the global nervous system, which has an analogue in the global communication and information networks. The slower hormonal communication system existing in all human bodies also has its counterpart: the world-wide post office system. Even the two brain hemispheres, the right and the left, may have an analogue in the Western and Eastern spheres of culture.
Other scientists state that mankind can be likened to a malign cancer in Gaia’s body. We have cut down the forests and polluted both water and air. But, like cancer cells, we are not aware that our own destructive activities will destroy Gaia’s web of life — the basis of our own existence. Which of the above views is the most realistic is at the moment not certain. It is quite possible that both views will be correct; nothing prevents a growing organism from struggling with cancer. Geophysiology is a new mode of synthesis and only time will tell.
In an attempt to sum up what has been discussed regarding the Gaia hypotesis, James Kirchner (1991) states that it must be viewed as a collection of related hypotheses. These in turn can be seen in a spectrum from weak to strong Gaia, from known biochemical cycles to global physiology. Kirchner found the following hypotheses, ranked from weakest to strongest Gaia:
- Influential Gaia — The biota has a substantial influence over certain aspects of the abiotic world such as temperature and composition of the atmosphere.
- Co-evolutionary Gaia — The biota influences the abiotic environment and the environment in turn influences the evolution of the biota by Darwinian processes.
- Homeostatic Gaia — The interplay between biota and environment characterized by stabilizing negative feedback loops.
- Teleological Gaia — The atmospere is kept in homeostasis not just by the biosphere but also by and for the biosphere.
- Optimizing Gaia — The biota manipulates the environment for the purpose of creating biologically favorable conditions for itself.
Finally, another kind of overview has been made by the scientist Kevin Kelly (1994) who said the following: “If Earth is reduced to the size of a bacteria, and inspected under high-powered optics, would it seem stranger than a virus? Gaia hovers there, a blue sphere under the stark light, inhaling energy, regulating its internal states, fending off disturbances, complexifying, and ready to transform another planet if given a chance”.
Source: Skyttner Lars (2006), General Systems Theory: Problems, Perspectives, Practice, Wspc, 2nd Edition.