Gaia Theory

Understanding of the evolution of atmospheric composition leads to the Gaia Theory.  By 1979 James Lovelock who had formulated the Gaia Theory had published some of his ideas in a first book "Gaia: A New Look at Life on Earth" in which the statement of the specification of the Gaia Hypothesis had become somewhat better defined. In this book we find him putting forward the postulate: ...the physical and chemical condition of the surface of the Earth, of the atmosphere, and of the oceans has been and is actively made fit and comfortable by the presence of life itself. This is in contrast to the conventional wisdom which held that life adapted to the planetary conditions as it and they evolved their separate ways.''

Just as human physiology can be viewed as a system of interacting components (nervous, pulmonary, circulatory, endocrine systems, etc), so too can the Earth be understood as a system of four principal components (atmosphere, biosphere, geosphere, and hydrosphere). Thus we find this more holistic approach the Gaian specification being made by Lovelock's use of this term "geophysiology" for the investigations of Earth, life and ecological science. As with human physiology, it emphasizes its biological base, the perspective of the whole system, and an interest in systemic health.

Certain claims concerning the Gaia Hypothesis could not be refuted - in particular the claim that the biota has a substantial influence over certain aspects of the abiotic world. We thus find Lovelock confident enough with the Gaia Hypothesis to the extent that he puts it forward - not as a hypothesis - but as the Gaia Theory:

The biota has a substantial influence over certain aspects of the abiotic world.  This is a supported observation within the Gaia theory.  "For more than a century students of the evolution of the living and nonliving parts of the Earth have known that life influences the physical and chemical characteristic of the planet. Nevertheless, the dominant paradigm in earth sciences has been that inexorable inorganic forces, such as changing energy output from the Sun, collisions of the Earth with extraterrestrial bodies, continental drift, or other orbital element variations have been the principal driving forces behind climate twenty years ago. James Lovelock and Lynn Margulis coined the phrase the Gaia hypothesis to suggest not only that life has a greater influence on the evolution of the Earth than is typically assumed across most earth science disciplines but also that life serves as an active control system. In fact, they suggest that life on Earth provides a cybernetic, homeostatic feeback system, leading to stabilization of global temperature, chemical composition, and so forth.

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