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The Gaia Hypothesis - Homeostasis

Earth
"Gaia theory is about the evolution of a tightly coupled system whose constituents are the biota and their material environment, which comprises the Atmosphere, the oceans, and the surface rocks.  Self-regulation of important properties, such as climate and chemical composition, is seen as a consequence of this evolutionary process. Like living organisms and many closed-loop self-regulating systems, it would be expected to show emergent properties; that is, the whole will be more than the sum of its parts."

James Lovelock, 1991. Geophysiology - The Science of Gaia, p. 4. In Scientists on Gaia, ed. Stephen Henry. Schneider, Penelope J. Boston, and American Geophysical Union.:3-10. Cambridge: MIT Press.

"The notion of the biosphere as an active adaptive control system able to maintain the earth in homeostasis we are calling the 'Gaia' hypothesis"
(Lovelock and Margulis 1974).

Daisyworld - a refutation of teleology

Daisy World

Dr Lovelock's Gaia hypothesis has discovered many processes that convert and stabilize the environment as evidence of Gaia at work. But coming from a reductionistic Darwinian paradigm, he is reluctant to accept a teleological perspective.  Yet ironically, many have criticised his hypothesis on precisely these grounds.

In response to the accusation of teleology, Lovelock introduced in his book The Ages of Gaia, the metaphor of "Daisyworld," a "drastic simplification" of the Gaia hypothesis.  Daisyworld is a hypothetical planet inhabited only by light and dark daisies.  The two kinds of daisies unwittingly cooperate to keep the temperature of the planet more constant than it would otherwise be.   The way it worked is like this.  The star warming Daisyworld increases its heat output over time. The environment is simplified as well. Its only component of concern is temperature and the biota, daisies. If the temperature is too cold (below 5o C) the daisies will not grow, or too hot (above 40o C) and the daisies will wither and die.  Dark daisies will automatically dominate the population (through natural selection) when the solar output is low (and thus absorbing more sunlight), and light daisies will dominate the population when the solar output is high (reflecting excess sunlight out to space). The number of daisies with dark or light colors to them are controlled by the system as a whole. Since all daisies want to exist at optimum conditions (20oC), the number of light daises will increase and the number of dark daisies will decrease over time, as solar output increases, to keep the mean temperature of the planet at the right temperature.

 Using computer simulations of the Daisyworld parameters. Lovelock found that the daisies did in fact keep the temperature to within the right range, until increasing heat poutput from the sun reached a level they could no cope with, in which case they all finally died.  This mathematical approach proved Lovelock's point about the controlled stability of the climate by life as not being teleological.

Web links Links Web links

on-line documentWHAT IS GAIA?  by James Lovelock

The Gaia Hypothesis - proposed by Dr. James Lovelock in collaboration with Dr. Lynn Margulis

web pagephotosGAIA - an excellent summary of Lovelock's hypothesis - by Brig Klyce

Daisyworld: a simple approach to geophysiological modelling - mirror site


The Weak Gaia hypothesis (non-homeostatic - Reductionist )
The Standard Gaia Hypothesis
(homeostasis)
you are here!
The Strong Gaia theory
(teleological)
The Goddess Gaia Earth
The Esoteric position
(hierarchies of consciousness)

parent nodeThe Gaia Hypothesis

parent nodeVarious Interpretations of Gaia


Geosphere
Biosphere

Gaia
Gaia

The Daisyworld simulation with its hard science approach means that the homeostatic interpretation of Gaia combines both the Objective Scientific and the Holistic-Organic paradigms.  If it has not found more widespread acceoprtence it is because of the resistence by the established (conservative) scientific paradigm


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content by M.Alan Kazlev
page uploaded 23 May 1999, last modified 19 August 2004