GAIA: The hypothesis

GAIA: The hypothesis proposed by James Lovelock that the earth is a living organism. It is an organic world picture as opposed to the mechanized world picture of the scientific revolution. (see machine) The name Gaia means Earth Goddess and was suggested to Lovelock by William Golding, author of Lord of the Flies. Leaving aside the anthropological element, the central element of Gaia theory is that the earth is a self-regulating system in which biological life does not simply adapt to conditions which happen to sustain life but in fact ensures the stablity (homeostasis) of those conditions. It is a form of coevolution between organism and environment.
earthrise

Were the earth not alive in this sense, it would resemble its dead neighbors, Mars and Venus. Lovelock cites the long - term stability of the Earth's atmosphere despite a 30% increase in the sun's radiation as a crucial indication of the earth's self-regulation. He describes himself as a Geophysiologist. The crucial difference for his approach is that geological and environmental change must be studied in conjunction with biological change, and that a concept of "Life" as self-organization informs that study. The policy implications of Gaia for conservation are somewhat ambiguous, since Lovelock believes that the power of the earth is much greater than that of homo sapiens . He downplays the catastrophic consequences of nuclear war, for example, suggesting that it might simply be a way for Gaia to purge herself of humans. The Gaia hypothesis is a curious mixture of anthropocentrism and of its opposite. While Lovelock describes Gaia as a goddess, a projection of human agency, he simultaneously downplayed the importance of humans for the life of the planet.

The Gaia hypothesis received considerable support from the studies of Lynn Margulies on the dynamics of microbial ecosystems and for her theories about the rise of Eukaryote cells as symbiotic unions of Prokaryotes.

Lovelock has given an extremely simplified model of this homeostatic process in "Daisyworld", a planet like earth revolving around a sun whose output is increasing, and in whose simplest version two types of daisies grow: dark and light. The change in Daisyworld's albedo (reflectance) is the only variable affecting the viablity of the planet for the growth of daisies. As the planet warms enough to support life the dark daisies begin to proliferate. They warm themselves more than the light ones and also warm the planet. As they warm the planet, the light daisies also bloom (they do better in the warmer climate as they cool themselves) The climate for life is thus maintained by the relative populations of light and dark daisies. As the sun gets hotter, more and more light daisies appear and continue to regulate the environment until the sun gets too hot and all life dies out. Lovelock claims that the addition of other species (for instance grey daisies) increase the possibilities of self-regulation especially during unstressed periods. In his second book, The Ages of Gaia, Lovelock expresses interest in Prigogine's work and rejects the "numerous modern mathematical scientists whose contemplations ot the demons of hyperspace - the " strange attractors" of chaos - are much more beguiling than the dull old real world of nature" (p.62)

see also self-organized criticality.