Reactive forms of oxygen, known as free radicals, are thought to cause ageing in people. Fruit flies raised at twice normal atmospheric levels of oxygen live half as long as their siblings. Divers breathing pure oxygen at depth suffer from convulsions and lung injury. The strange and profound effects that oxygen has had on the evolution of life pose a riddle, which this book sets out to answer. High oxygen levels may also explain the global firestorm that contributed to the demise of the dinosaurs after the asteroid impact. Giant spiders, tree-ferns, marine rock formations and fossil charcoals all tell the same story. Researchers claim they could have flown only if the air had contained more oxygen than today – probably as much as 35 per cent. Three hundred million years ago, in Carboniferous times, dragonflies grew as big as seagulls, with wingspans of nearly a metre. Oxygen has had extraordinary effects on life. Yet if atmospheric oxygen reached 35 per… ( tovább)
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