James Lovelock who write "Gaia: A New Look at Life on Earth" and "The Ages of Gaia" believes that science can demonstrate that the Earth is a living organism. At least, it maintains basically the same conditions in temperature, atmosphere, salinity and pH of the oceans, etc. These reflect commensurate conditions that should occur in living organisms. So, he comes up with the Gaia hypothesis based on the complex physical, chemical & biological interrelationships that work like a living organism. How can he claim that the Earth is a living organism?
He draws a parallel with the mighty redwood tree. With insights from physicist, Jerome Rothstein, he points out that 99% of a redwood is dead. It is "an ancient spire of dead wood, made of lignin and cellulose by the ancestors of a thin layer of living cells" (p.10). Similarly, it is theorized that many of the atoms that compose the rocks in the magma at the core of the Earth, were once part of our ancestral life. So, even "dead" elements are included within the biosphere of living organisms.
One thing I found surprising is that the chemical composition of Earth's atmosphere is comprised of chemicals that should react in a volatile manner, creating a state of disequilibrium. However, conditions on Earth have stayed favorable for life for 3.5 billion years without let up, (this is derived from the record of sedimentary rock). The so-called "ice-ages" (a hyperbolic term, apparently) only occured above north of the 45 degree North latitude and below the 45 degree South latitude. 70% of the remaining surface was mostly unaffected by these freezings. So, something about the Earth functions "like" a living organism to bring equilibrium; this implies design and Lovelock points to the Earth itself for answers.
I found a nice summary online of Lovelock's three points in this book:
"The 3 major principles he brings to light about Gaia are:
1. Gaia exhibits a tendency to keep conditions (e.g., temperature, air quality) constant for all terrestrial life.
2. Like other living systems, Gaia has vital organs at the core, and expandable or redundant ones on the periphery.
3. Under the worse conditions, Gaia responses similar to other cybernetic systems (i.e., where time constant and loop gain are important)"
A major implication of Lovelock's work is the interrelationality of all living things. Ecologically speaking, even so called "dead" things are interrelated with "live" things. We don't consider a redwood a mostly dead thing, and yet it is composed of mostly dead things. Similarly, humans in their environments are surrounded by things that seem unrelated or dead (at least in connection), but they should be considered according to Lovelock.
Whether we agree or disagree with Lovelock's conclusions, his method should inspire the way we create models. He asked expansively curious questions. Questions that would seem to resist even a sensical begninning point.
It seems that I should be gleaning more implications if Lovelock's theory has merit, that the Earth is a living organism. What else should I be considering?
Here's something to consider: That God IS the universe, i.e., Being-Itself (Tilllich), not a guy with a beard sitting around someplace a long way off waiting for us to show up there. You've got it right when you note that the questions raised by Lovelock resist a rational, sensible beginning point; they also resist a final answer ("I am that I am--the Beginning and the End"). Lovelock is doing post-modern science in relation to the age-old questions of life and reality.
JIM'S ADDITIONAL COMMENTS
One of the most significant learnings about ecology for me occurred a number of year ago when I attended a conference on epistemology at which Gregory Bateson, Humberto Maturana, Heinz von Forester, and others presented. I will always remember a presentation by a geologist (whose name I don't recall), during which he held up a large rack of test tubes in a darkened auditorium, and showed the audience all the colors of the rainbow in the light passing through them. He explained that these were layers of sedimentary rock obtained by taking core samples from the area of the Painted Desert in Utah. The colors were created by a broad spectrum of aerobic and anaerobic bacteria, which over eons of time had found a way to co-exist in the same space by utilizing the atmospheric resources available. The concept of Gaia has been real (and concrete) to me ever since.