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The Medea Hypothesis: A response to the Gaia hypothesis

A new book, 'The Medea Hypothesis,' looks at the opposite of the Gaia hypothesis and suggests that life on Earth is self-destructive.

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In terms of biomass — the pure weight of all things living — our planet is already past its prime anyway. From here on out, quite independent of human activity — which isn't helping, of course — there's going to be less and less life. We're on the down slope. We're on a planet already in its old age.

Before anyone gets too anxious, Ward's dates need some perspective. While it's true that life has been around quite along time, it's also true that multicellular life – from trees to jellyfish to dinosasurs and people – has been around a small portion of that, since just before the so-called Cambrian explosion about 530 million years ago.

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In other words, multicellular animal life evolved in the ocean, colonized land, and become us in roughly the same amount of time that we've got left.

More perspective: The primate lineage — monkeys, apes, gibbons and lemurs — stretches back 55 to 58 million years ago, about one-ninth of what we've got left, according to his hypothesis.

Even more perspective: The most recent common ancestor of all great apes — gorillas, chimpanzees, orangutans, and us — lived 14 million year ago, one-36th of what he says remains. And the common ancestor of humans and chimpanzees, our closest existing relative, lived just over 6 million years ago, an 83rd of the time left.

Further perspective: Modern humans have existed some 200,000 years. Multiply that by 2,500 and that's what we've got left, according to Ward.

In other words, we've got some time.

And yet, it's understandable that some readers find Ward's argument depressing. At, one reader calls "The Medea Hypothesis" "A Dark Book for Eggheads About Biocide." The book is "Dark, Difficult, and somewhat depressing," writes another.

But Ward's purpose in writing "The Medea Hypothesis" doesn't seem to be to elicit despair.

Indeed, although it's not apparent throughout much of the book — it would have been nice had he balanced his exploration of the past with one of the future — Ward seems to be arguing in an oblique way that Homo sapiens, with our capacity to plan in advance, are not just our own best hope, but the only hope for all of life on Earth.

He's trying to emphasize the importance of our arrival on the scene not just to ourselves, which is obvious, but to the entire biosphere. In the long run — and we're talking in the very long run here — only human ingenuity will save life from a planet that's always had an expiration date anyway.

Toward the end of the book, Ward says, "There is some dark irony in what must be done. In the near term we must reduce atmospheric CO2. Then, in the long term, we must move to keep CO2 from falling too far. But with significant engineering, both are readily possible."

And so Ward brings us full circle. Life is Medean, he's argued for 140 pages, not Gaian. By its very nature, it's self-destructive. The only hope in the very long run is through human foresight and planning, to ensure continued survival.

Then, he implies, life on Earth life will have finally overcome its Medean nature. It will have become truely Gaian.

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