The Reductionist theory of the Earth is the one most acceptable to the sceptical viewpoint of conservative orthodox science. It assumes a non-homeostatic understanding.
In this paradigm, it is acknowledged that the environment of Earth has evolved just as life has. But although the evolution of life and the planetary environment may affect each other (e.g. through the photosynthetic acivities of blue-green algae during Precambrian time the composition of the atmosphere has completely changed from anaerobic to oxygen rich), but not in any sort of coordinated or homeostatic manner. Life consumes resources and discharges waste products; and these processes alter the environment. The environment being altered presents new challenges and even new opportunities to life. e.g. the oxygen crisis enabled the rise of eukaryotic life. But this is purely a random chance interaction, and things could go either way. So far, life has been able to meet the challenges, but this is just luck.
To give an example of a non-homeostatic explanation of "Gaia", the change in the amount of carbon dioxide, which is necessary to the continuation of life through maintaining the correct amount of carbon dioxide in the atmosphere, does not have to be due to a homeostatic carbon cycle. The orthodox position is that the global decline of carbon dioxide over billions of years (which has enabled the temperature to remain constant despite increasing solar output) could have been due to rainwater that dissolves carbon dioxide to form carbonic acid, which then dissolves calcified rocks. The then neutralized acid will run into the sea, performing chemical weathering of said rocks along the way .
Jim Kirchner () argues that there are really many Gaian hypotheses. Two of these are
1.Influential Gaia, the weakest of the hypotheses, asserts that biota have a substantial influence over certain aspects of the abiotic world, such as temperature and the composition of the atmosphere.
"The Gaia hypothesis.. states that the temperature and composition of the Earth's atmosphere are actively regulated by the sum of life on the planet"
(Sagan and Margulis 1983).
2.Co-evolutionary Gaia
asserts that the biota influence their abiotic environment, and that the
environment in turn influences the evolution of the biota by Darwinian
process.
"The biota have effected profound changes on the environment of the surface of the earth. At the same time, that environment has imposed constraints on the biota, so that life and the environment may be considered as two parts of a coupled system"exerpted from
(Watson and Lovelock 1983).
The
Debate over the Gaia Hypothesis
The above have been referred to under the heading of the "weak Gaia hypothesis", but in fcat they do not actually even postulate that the Earth is a homeostatic living super-organism. Strictly speaking then they are not really part of the Gaia hypothesis at all, but rather represent the conservative old-paradigm approach to the nature and dynamics of the Earth and life on her. Nevertheless they are still valid observations, and represent a part of the overall picture
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James
Lovelock's Gaia Hypothesis: Past, Present, and Future- by Michael
Farb - a critique
The
Debate over the Gaia Hypothesis
Kirchner, J.W. 1991. The Gaia hypothesis: Are they testable? Are they useful? In Schneider, S. (ed.) Scientists on Gaia. Cambridge, MA: MIT Press.
Gaia
- Is Good Mother Earth taking science too far? - a very critical
approach to the Gaia hypothesis - states that Lovelock never claimed that
the Earth be taken as a superorganism. Is agnostic towards the possibility
of a reductionist homeostatic theory of Gaia
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(non-homeostatic Reductionist) you are here! |
(homeostasis) |
(teleological) |
(sentient - Goddess Earth) |
(hierarchies of consciousness) |
Various
Interpretations of Gaia
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