Reading4_5_Lane_Origin

Reading4_5_Lane_Origin - Lane Life Ascending THE ORIGIN OF...

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Lane – Life Ascending 1 THE ORIGIN OF LIFE From Out the Turning Globe From Lane, Nick (2009) Life Ascending: The Ten Great Inventions of Evolution . W.W. Norton & Company, N.Y. ight followed day in swift succession. On earth at that time a day lasted for only five or six hours. The planet spun madly on its axis. The moon hung heavy and threatening in the sky, far closer, and so looking much bigger, than today. Stars rarely shone, for the atmosphere was full of smog and dust, but spectacular shooting stars regularly threaded the night sky. The sun, when it could be seen at all through the dull red smog, was watery and weak, lacking the vigour of its prime. Humans could not survive here. Our eyes would not bulge and burst, as they may on Mars; but our lungs could find no breath of oxygen. We 'd fight for a desperate minute, and asphyxiate. The earth was named badly. 'Sea' would have been better. Even today, oceans cover two-thirds of our planet, dominating views from space. Back then, the earth was virtually all water, with a few small volcanic islands poking through the turbulent waves. In thrall to that looming moon, the tides were colossal, ranging perhaps hundreds of feet. Impacts of asteroids and comets were less common than they had been earlier, when the largest of them flung off the moon; but even in this period of relative tranquillity, the oceans regu- larly boiled and churned. From underneath, too, they seethed. The crust was riddled with cracks, magma welled and coiled, and volcanoes made the underworld a constant presence. It was a world out of equilibrium, a world of restless activity, a feverish infant of a planet. It was a world on which life emerged, 3,800 million years ago, perhaps animated by something of the restlessness of the planet itself. We know because a few grains of rock from that bygone age have survived the restless aeons to this very day. Inside them are trapped the tiniest specks of carbon, which bear in their atomic composition the nearly unmistakable imprint of life itself. If that seems a flimsy pretext for a monumental claim, perhaps it is; there isn’t a full consensus among experts. But strip away a few more skins from the onion of time and, by 3,400 million years ago, the signs of life are unequivocal. The world was heaving with bacteria then, bacteria that left their mark not just in carbon signatures but in microfossils of many diverse forms and in those domed cathedrals of bacterial life, the metre-high stromatolites. Bacteria dominated our planet for another 2,500 million years before the first truly complex organisms appeared in the fossil record. And some say they still do, for the gloss of plants and animals doesn't match the bacteria for biomass. What was
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This note was uploaded on 03/08/2011 for the course BIS 2A taught by Professor Grossberg during the Fall '08 term at UC Davis.

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Reading4_5_Lane_Origin - Lane Life Ascending THE ORIGIN OF...

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