Gaia Hypothesis Essay ⋆ Environment Essay Examples ⋆ EssayEmpire

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The Gaia hypothesis asserts that the earth is a single living organism with the power of self-regulation. It was the brainchild of James Lovelock and Lynn Margulis, who chose to name their theory Gaia after the Greek goddess of the earth. While the idea that the earth is alive and is the great mother to all life has very ancient roots, the idea has traditionally been regarded as a kind of metaphor for the connectedness of life, rather than scientifically demonstrable fact. However, Lovelock and Margulis employed scientific arguments in their claim that life on earth was part of a great cybernetic system with complex feedbacks, and that these, in turn, regulated the system keeping it operating within narrow bounds. They claimed that life (the biosphere) regulated the composition of the atmosphere and this regulated the temperature of the planet. Such self-regulation demonstrated that the earth was an organism like any other. Gaia initiated a debate in scientific circles that still continues. Gaia also attracted attention from the media, certain environmentalists, the clergy, and even religious mystics.

Lovelock’s unique background led him to the Gaia Hypothesis. He was an independent scientist and inventor who had also worked for NASA on the Viking program, the first satellite to land successfully on the surface of the planet Mars. One of the objectives of the Viking mission was to test the surface for evidence of life. This led Lovelock to a strange conclusion-that it was not necessary to probe the surface of Mars to test for life. If life existed, it would alter the composition of the atmosphere. Since the relative proportions of the gasses in the Martian atmosphere had already been determined by traditional astronomical techniques, there was no need to send a probe to the surface to look for life. The composition of the atmosphere indicated that it was a lifeless planet. In dramatic contrast, the mixture of gasses comprising the earth’s atmosphere revealed that it was a living world. The high proportion of oxygen, the by-product of photosynthesis, was perhaps the best indication of life.

Lovelock claimed that the earth regulated its temperature by regulating the composition of the atmosphere. For example, oxygen has a historical proportion of about 21 percent. If this value were much lower, perhaps 18 percent, combustion could not be sustained in most cases. If this value were much higher, perhaps 25 percent, then fires would burn wildly. The very fact that the mixture of gasses in the atmosphere had remained within very narrow bounds for eons was extremely unlikely, in fact impossible; and therefore, required some regulatory mechanism connected to life processes. In addition, the sheer volume of oxygen as a free gas made the earth’s atmosphere unusual compared to the other inner planets of the solar system, and indicated a kind of chemical disequilibrium in which it was continually destroyed and created. Oxygen was inextricably connected to the forces of life, specifically photosynthesis. Such regulation of atmospheric composition was more evidence that the earth was operating as a single living organism. However, critics charged that this was not evidence of regulation at all, but simply the result of the planet’s interacting living and geophysical systems.

One of the most difficult criticisms to refute was the charge that the Gaian system was teleological, that is, preordained. The dictionary definition of teleological is that it concerns the study of evidence of design in nature. Teleology is a doctrine that nature or natural processes are directed toward an end or shaped by a purpose. According to this reasoning, Gaia was teleological because the plants and living systems were programmed to regulate the earth system.

To answer some of the critics, Lovelock resorted to creating a computer model of an artificial planet called Daisyworld. It was a simple planet, which had only one life form, the daisy, which came in two varieties: one light and one dark. The relative proportion of each determined the albedo or reflectivity of the planet. Albedo is critical in determining the temperature, because sunlight reflected back out to space is lost to the system. Only the sunlight that is absorbed serves to heat the planet. Lovelock tried to show that such regulation of the planet’s temperature through the regulation of albedo by living organisms (daisies) was simply the result of a living system interacting and modifying its geophysical environment. It did not require any forethought or planning by the living organisms, and, therefore, it was not teleology. For the most part, the critics remained unimpressed, claiming that the Daisyworld model only reflected the assumptions underlying its construction and its relation to the actual functioning of the earth system was minimal or nonexistent. Lovelock believed that the critics ignored the power of the Daisyworld model. Some of his supporters praised his efforts for their simplicity and elegance in clarifying basic regulating mechanisms on an earthlike planet. Ultimately, the Daisyworld model became the basis for the popular computer game, SIMEARTH.

The power of the Gaia Hypothesis reached well beyond its scientific origins. Throughout history, people from a variety of religious backgrounds have viewed the earth as the mother goddess of all life. Furthermore, the idea that the evolution of the earth prepared the perfect habitat for humankind had a powerful appeal. Lovelock, who had now provided a scientific basis for such beliefs, was stunned by the attention Gaia received from beyond the scientific community.

The Gaian theory called attention to the role of the biosphere in the complex geophysical relationships of planet earth. The physical systems of the earth and the biological systems of the earth evolved together, and each affects the other. Life is vastly more important to the earth system than simply a passenger on a pile of rocks. The issue of whether Gaia is simply a provocative metaphor or genuine cybernetic system will never be completely settled.

Bibliography:

James Kirchner, “The Gaia Hypothesis: Fact, Theory, and Wishful Thinking,” Climatic Change (v.58, 2002);
James Kirchner, “The Gaia Hypothesis: Conjectures and Refutations,” Climatic Change (v.58, 2003);
James Lovelock, Gaia: A New Look at Life on Earth (Oxford University Press, 1979);
James Lovelock, The Ages of Gaia (W.W. Norton, 1988);
Lynn Margulis and Gregory Hinkle, “The Biota and Gaia: 150 Years of Support for Environmental Sciences,” in Stephen Schneider and Penelope Boston, eds., Scientists on Gaia, (MIT Press, 1991).