Filed under: Earth history
A bit of catch-up. Just before dashing off to Copenhagen I had the chance to spend some time with Jim (and Sandy) Lovelock, some of which was at and after a Nature event and some more of which will soon be making it to a Nature video, I hope. Jim is, among many other things, a master of analogy, and I was struck by a new one that he was road testing — one that mixes catastrophe and optimism in a way that chimes with his new book, but which is not I think spelled out there.
The analogy is between oxygen and intelligence, and the creatures — cyanobacteria and humans — which brought these new and terrible entities to the world. In both cases, there were precursors. There are non-biological processes which produce free oxygen, and there is intelligence of various sorts elsewhere in the animal world. But in both cases there was at a specific point a quantitative shift so huge as to be qualitative and then some. Cyanobacteria really did overturn the biosphere 2.45 billion years ago, and they and their descendents have shaped it ever since; human intelligence has done so too, from the Pleistocene die-offs onwards.
Lovelock’s point is that an evolutionary breakthrough in a single form of life can have global consequences and that such a breakthrough can be — probably must be — highly destabilising, even catastrophic. The presence of free oxygen was a huge change in the terms on which life prospered on the earth, since everything that came before was based on anaerobic metabolisms: many niches and perhaps species were wiped out. Similarly, intelligence of the sort demonstrated by humans is proving far from benign on a global level, with ever increasing stress on ecosystem services and, as with oxygen, wholesale rewiring of various biogeochemical cycles.
Yet in time, for all the disruption it caused early on, oxygen became the basis of something far grander than what had come before. The amount of free energy available to the biosphere increased spectacularly, with reasonable levels of oxygen facilitating complex multicellular life in way which may well be impossible in an anaerobic world (Catling et al [pdf]). All the life you see and care about is made possible by that oxygen (though not all the life that you depend on — at the deep biogeochemical level the microbes, including the anaerobic ones, still rule). Similarly Jim suggests that, in time, intelligence may make possible a more wonderful planet in ways we can hardly guess at today and bring forth a “wise, thoughtful world”.
There are what seem to be weaknesses to the analogy. Many (including, FWIW, me) continue to believe that oxygenic photosynthesis was around for a long time before oxygen was able to build up in the atmosphere — hundreds of millions of years, maybe even a billion — and that the eventual breakout of oxygen in the Great Oxidation Event of 2.45 billion years ago was not quite the catastrophic holocaust that it has previously been portrayed as, and which Jim still feels it was. But a) we may be wrong (Joe Kirschvink certainly thinks so [pdf]) and b) that may not matter too much. This is an analogy, after all.
And as an analogy, Jim takes it one intriguing stage further. While cyanobacteria still abound, they are no longer the sole source of oxygen, nor even the dominant one. The cyanobacteria not only made new life forms possible — they also incorporated theselves into them, in the form of chloroplasts. The ability to make oxygen was disseminated into creatures radically unlike the original cyanobacteria — into kelp forests and elm trees and cactuses and camelias. Perhaps, Jim suggests, the same is true of intelligence — that its destiny is to be spread far beyond the species in which it first originated, into new achitectures of life and thought.
It’s an idea that may sit uneasily with Lovelock’s current pessimism, which sees human activity as bound to lead to a fairly massive die-back. But it flows easily from the tradition of thought that Lovelock (and Freeman Dyson, and the late Arthur C. Clarke) drank from as a young man, a tradition that combines a respect for thermodynamics (there’s a free-energy/information level to Lovelock’s analogy that would probably be interesting to tease out) with a cosmically-contextualised yearning for transcendence. It’s a tradition that retains its power to move today, and it’s a thought-provoking pleasure to hear him give it voice.
Images: Death in Biscay by Christian Darkin on the basis of MODIS imagery commissioned for a great feature by Nick Lane that Nature ran last year, all rights reserved; brainy stromatolite from mjwy’s guide to stromatolites on eBay
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