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January 17, 2009

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Randy McDonald

I've always been of the opinion that extraterrestrial life is common but doomed to exist in resource-scarce environments, like Martian caverns, freezing oceans of ice moons, or in the upper atmosphere of Venus.

The Many Deserts phenomenon?

Noel Maurer

I have no comment on the Gaia Hypothesis, because to be honest, I don't know what it is. But the Medea Hypothesis sounds very wrong, simply because it seems unlikely in the extreme --- by definition --- that the Earth rolled a six every time it came up in paleohistory.

Unstable ≠ suicidal. Or, from the article: "Stephen Schneider, a climatologist at Stanford University, is more dismissive. 'Anybody who tells you [the feedbacks] are all positive or all negative is writing a potboiler.'"

I see why Ward is writing his book; it's a worthy corrective to fuzzy-mushy-nature worship. And it adds a healthy sense of panic to worries over what humanity is doing to its environment. But the idea in-and-of-itself, as Ward presents it, of a planet full of positive feedbacks doesn't sound that interesting.

Scruffy marginal life on Mars, however, would be that interesting. And rather depressing, if no more so than an utterly lifeless Mars. But the jury is still way out, Doug. It's a bit of an exaggeration to say that "methane emissions on Mars ... are pretty hard to explain except in terms of life," no?

Will Baird

"I have no comment on the Gaia Hypothesis, because to be honest, I don't know what it is. But the Medea Hypothesis sounds very wrong, simply because it seems unlikely in the extreme --- by definition --- that the Earth rolled a six every time it came up in paleohistory."

Except it came up a lot more often than what Ward implies. He makes it sound like there were only a handful of situations where the life tried to do itself in. Bullpucky. There have been numerous mass extinctions of varying degrees. The Big Five/Six only stand out because they are the statistical far end of the distribution, not for their effects. He's cherry picking. :P

"I see why Ward is writing his book; it's a worthy corrective to fuzzy-mushy-nature worship. "

Indeed. It's also knocking the Gaia Hypothesis - or at least one interpretation of it - over the head with a large marble statue. The basic idea that the Greenies takes that so irritates me is that the world was in a pristine state prior to people and would be without us. The Edenic State never existed and, in fact, vast chunks of EVERYTHING are very, very, VERY new. The Amazon rain forest has only existed for a handful of thousand years. The Yucatanian tropical forest was uber cleared prior to the Mayan "Collapse." The whole of the Canadian North used to be barren rock after the glaciers retreated as well.

The world IS NOT in some sort of stable state. Sheesh. Life does have some helpful, self preserving feedback mechanisms though.

"Meanwhile, here's a speculation: what if the Mars model is the norm? If the universe is full of life, yep, sure enough -- and virtually all of it consists of small, marginal groups of microbes barely clinging to existence? "

um. I guess I have always expected that.

And Earth, with its teeming biosphere, wildly disequilibriated atmosphere, and great lumbering multicellular organisms everywhere, is the far far end of the distribution curve?"

Could be. To some extent probably.

We need more data. What-if Europa, Callisto, Ganymede, and Iapetus are the norm for worlds with life? If one of those has advanced multicellular life - even as far down the life as Ediacaran - I'd say we have a fascinatingly high percentile of complicated life. OTOH, all three have "bacteria" or nothing ...

BTW, Ward's books are rather pessimistic. Read Future Evolution, frex, for that. Or Under a Green Sky. He also has a higher than I would have expected opinion of humanity too: he considers us the first unkillable species.

Human Exceptionalism.

*bemused look*

Dennis Brennan

I have only a passing familiarity with the Gaia hypothesis, but I was under the impression that it was quite contrary to greenie dogma-- namely that the hypothesis boiled down to: "bitch slap Mother Earth all you like, life (in some form) will come back".

Will Baird

mmm. The original GH as I understand it was that the world's organisms act as a superorganism that regulates the ecology like a complete body. It gets sick and it gets better.

as originally proposed, it's been rejected. The originators have backed fof and refer to it as a set of feedback loops.

The Greenies have taken it, as I have encountered it, that if you undo human caused damage, the environment will heal itself and that Mother Nature's a nurturing environment. It's so completely wrong, I can't even begin.

Mom's a ahem and eats her kids, but not necessarily in the way that Ward thinks.

Ikram

Noel wrote:
seems unlikely in the extreme --- by definition --- that the Earth rolled a six every time it came up in paleohistory

Anthropic principle.

Noel Maurer

That seems like just a fancy way of saying, "Well, unlikely stuff happens."

Sure it does. But not often. So Occam's razor leads me to reject the strong form of the Medea hypothesis unless compelling evidence is presented to the contrary.

And just to reiterate: the ecology is unstable ≠ positive feedbacks reign supreme. The evidence is that the ecology is unstable for human definitions of unstable, and is not unstable for carbon-based biological life definitions of unstable.

Right, Will?

Bernard Guerrero

I dunno, Noel. Can you call something like the Oxygen Catastrophe "not unstable for carbon-based biological life definitions of unstable"? I mean, ok, at the end there is still carbon-based biological life, but the basis of something as fundamental as metabolism is completely different.

Noel Maurer

Fair point, Bernard, but there are still two questions left unanswered.

(1) In a counterfactual where an oxygen-using exosystem was impossible, would the result have been the death of all life or reversion to something like the previous ecosystem? If the latter, then the Medea hypothesis is false.

(2) If the former, then the Medea hypothesis might be true ... for that one singular event. I find it quite plausible that the Earth rolled a six once in its history. It's the idea that it had to get lucky over and over and over again that seems unlikely ... especially when there are simpler hypotheses to explain life's persistence.

No?

Michael White

Hi. This is an interesting post definitely. Please post more like it soon. Thank you for posting it! Mars is a good planet... I say that we start terraforming it. :)

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