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Ozone Loss Caused Genetic Mutations At Time Of Mass Extinction
London (SPX) Aug 11, 2004 Research into the world's worst mass extinction, which led to the loss of 90 per cent of living species 250 million years ago, has found that the historical tragedy also involved some disturbing genetics mutations. The Open University's Dr Mark Sephton, who was part of an international team of scientists from the Netherlands and the United Kingdom who uncovered the remarkable new information, said: "The mother of all mass extinction just got worse." The findings are to appear in the latest Proceedings of the National Academy of Sciences (PNAS) magazine, published today. "In our work we have found that at the time of the end-Permian extinction increased amounts of ultraviolet light filtered through the Earth's surface and caused damage to the DNA in plant spores. The results were abnormalities that prevented plant life from reproducing and a consequent collapse of terrestrial ecosystems," says Dr Sephton. "The cause of the increased intensity of ultraviolet light was a disruption in the Earth's ozone shield. Massive volcanic activity that was taking place in Siberia at this time forced chlorine and bromine containing gases into the stratosphere where they catalytically destroyed ultraviolet-absorbing ozone gases. It was only when volcanic activity subsided, that life on earth could begin to recover from its biggest ever catastrophe," he concluded. Dr Sephton believes the results heed an important warning for today's society: "We are bringing the effect of human activity on ozone depletion under control but the end-Permian example shows us that natural volcanic activity can cancel out all our good efforts." The article "Environmental Mutagenesis during the End-Permian Ecological Crisis" which Dr Sephton co-wrote with Henk Visscher of Utrecht University in the Netherlands was published on PNAS Online in July. Community Email This Article Comment On This Article Related Links SpaceDaily Search SpaceDaily Subscribe To SpaceDaily Express Explore The Early Earth at TerraDaily.com
Oxygen in Ancient Atmosphere Rose Gradually To Modern Levels
College Park MD (SPX) Dec 03, 2005The history of life on Earth is closely linked to the appearance of oxygen in the atmosphere. The current scientific consensus holds that significant amounts of oxygen first appeared in Earth's atmosphere some 2.4 billion years ago, with a second large increase in atmospheric oxygen occurring much later, perhaps around 600 million years ago. |
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