Sunday, October 16, 2011

The Medea Hypothesis: Is Life on Earth Ultimately Self-Destructive?

After wasting pages on an ad hominen argument that belabors the New Age movement's adoption of James Lovelock's Gaia hypothesis, Ward finally gets down to the serious business of trying to refute/debunk Lovelock's hypothesis.

The Gaia hypothesis, varying from weak to strong versions, involves the notion that Earth's biosphere actively regulates the chemistry and temperature of its fluid environment--the atmosphere and oceans--to keep the planet bio-friendly. Ward cites extreme fluctuations in atmospheric chemistry and temperature in Earth's past, ascertained from geological evidence, and proposes mechanisms by which the biosphere's own metabolic processes could have contributed to the extremes. The extremes reduced Earth's overall biomass, and, so Ward argues, the biosphere not only fails to maintain a healthy environment for itself, but positively contributes to disrupting the environment and reducing the planet's biomass. Hence, the Gaia hypothesis is disproven and Ward's Medea hypothesis, that life poisons its environment and so is inherently suicidal, is corroborated.

The argument is not convincing for a few reasons. For one thing, life always participates in anabolic (building up) and catabolic (tearing down) processes. The two feed each other, and the combined system is called metabolism. To focus on the downside is not to discredit the circuit.

Ward settles on biomass as the "bottom line" measure of the health of the biosphere. But do we assess the health of any organism solely by mass? Evolution has produced advanced technological civilization. What more could be expected from a living planet? More and more and more bacterial tonnage? Biomass per se is not an indicator of anything in particular, except biomass.

In a previous book, Ward (and co-author Donald Brownlee) suggested that glaciations serve evolution as genetic filters, weeding out the less fit. So he's familiar with the idea that die-offs can serve a constructive evolutionary purpose, even if they reduce biomass.

What Ward fails to address, and what is central to Lovelock's original idea, is the anomalous resistance of Earth's fluid environment to entropy. Why are the atmosphere and oceans not sitting stable in a state of chemical equilibrium after all these millions of years? Volcanism, mineral erosion and other geochemical processes continually stir the pot, but surely it is an oddity that the random variability never has crossed a threshold that would've sterilized Earth.

Part of Ward's problem seems to be that he fails to connect Gaia with evolution.

A fetus also pollutes its environment, and up to a point it's not a problem, because the environment not only is set up to handle the toxins, but also positively to support the developing life. Up to a point. A fetus that stays in the womb too long becomes Medean--life threatening--at which time it needs to move to a more accommodating environment.

That's the situation we're in.

Ward has no enthusiasm for space colonization, but thinks it's wiser to try to adapt to this planetary womb. Such short-sighted thinking definitely is Medean. Ward's book presents a half-baked recipe for a self-fulfilling stew.