Explain me this hippy-science.

March 2, 2008 6:40 AM

Who can help explain James Lovelock's Gaia to me?

OK, so I read this rather terrifying article, and decided to try and find out more about Lovelock's Gaia idea. However, an extremely interesting couple of hours of reading around the subject has left me a little confused, and I have two (related) questions that I can't seem to find answers for:

1. The Gaia hypothesis an attempt to explain that throughout history we observe an unexpected stability of certain conditions favourable to life (atmospheric composition, global temperature, ocean salinity etc.) How do the scientists who reject Lovelock's theory account for these unexpected stabilities?

2. The broad thrust of the criticism of Gaia seems to come from the fact that it fails to explain the mechanisms which make the homeostasis work. Is this a fair criticism? Have Gaia theorists outlined any such mechanisms at all?

Essentially I'm wondering if there is any conflict between the two sides, both of which seem to me to be just coming at an unexplained phenomenon from different angles.

posted by greytape to Science & Nature (4 answers total)

Best answer: I'd recommend Colin Tudge's book The Time Before History (published in the UK as The Day Before Yesterday) and Jonathan Weiner's The Next One Hundred Years for readable surveys of the ideas at hand (planet-scale homeostasis). Kevin Kelly wrote about Lovelock in Out of Control (relevant chapter online). Here's a New Scientist review of Tudge's book.

I'd also recommend a couple of books by E. C. Pielou, The Energy of Nature and Fresh Water, which also deal with the Earth as a whole system, trying to think about how it works at the largest scales. For another more lyrical approach to thinking about the Earth, read Evan Eisenberg's Ecology of Eden and Jonathan Schell's Fate of the Earth (this latter is about nuclear disarmament but deals with the effects of nuclear weapons on the Earth in passing; it's very much worth reading).

As far as Gaia goes, I think it's becoming more acceptable among younger biologists and geologists, who understand its original theoretical import as Lovelock intended it, rather than as a weird metaphor for a deific entity. Gaia is a name for the homeostatic characteristics of the whole system over time, the tendency of the atmosphere retain its proportions of component elements although the physics suggests many other less demanding states (like Venus's or Mars's, to name two). My impression could be terrifically wrong, though, as it comes mostly from pro-Gaia writers like those at Edge.org and other so-called "Third Culture" folks, and because I'm biased in its favor anyway.
posted by cgc373 at 7:56 AM on March 2, 2008

Best answer: To answer your questions a little more specifically (and sorry for the missed first attempt there), scientists who reject the Gaia idea focus elsewhere in their studies than the large scale Gaia is supposed to describe. Gaia attempts to shift paradigms—to get all pop-Kuhn on it—to a macro-level unusual for biologists or geologists, more in line with astronomers' level of abstraction, I think. Since it's not what Kuhn called "normal science," it's less "rejected" than simply ignored, considered irrelevant when it comes down to studying the systems various scientists choose to study.

And as for the mechanisms Gaia theorists themselves put forth, I think the best-known of them is a computer model called Daisyworld, which you probably saw in your few hours of reading. Whether such a model can account for the way the world is, is a question about the effectiveness of models in science, which is deep, deep water, too deep for me to want to dive into. (Though I can point to Wigner's canonical question about the unreasonable effectiveness of mathematics in the natural sciences as a source for further thought.)
posted by cgc373 at 8:07 AM on March 2, 2008

Kirchner on Gaia. More.

Scientists on Gaia book on amazon.

Lots of criticism at the wikipedia too.

From the skeptic faq:

7.2: What is the Gaia hypothesis?
---------------------------------

There are several versions. The following taxonomy was suggested by
James Kirchner in "Scientists on Gaia":

* Influential Gaia: the biota has a substantial influence over certain
aspects of the abiotic world

* Coevolutionary Gaia: the biota influences the abiotic environment, and
the latter influences the evolution of the biota by Darwinian processes.

* Homeostatic Gaia: the interplay between biota and environment is
characterized by stabilizing negative feedback loops.

* Teleological Gaia: the atmosphere is kept in homeostasis not just by
the biosphere, but in some sense _for_ the biosphere.

* Optimizing Gaia: the biota manipulates its environment for the purpose
of creating biologically favorable conditions for itself.

I'd say no one disputes Influential Gaia, and no serious scientist
supports Optimizing Gaia (though some of Lovelock's earlier remarks
tend in that direction). Most of the scientific debate surrounds
Coevolutionary and Homeostatic Gaia. Some point to Le Chatelier's
principle (a system in equilibrium, when disturbed, reacts to as to
tend to restore the original equilibrium). However the ice ages
suggest that the Earth is not in long-term equilibrium.

posted by damn dirty ape at 10:45 AM on March 2, 2008

Also, its teleological as all hell. You say "throughout history we observe an unexpected stability of certain conditions favourable to life." It took 4 BILLION years to get from nothing to our first vertabrae (fish). I think the entire hypothesis is based on focusing on recent history and forces evidence to fit into the hypothesis because there's life everywhere thus the world was made for life. That doesnt hold. That's blind teleology.
posted by damn dirty ape at 10:49 AM on March 2, 2008