In a discovery that could radically change our understanding of the origins of life, scientists have found that oxygen and the life that generates it might have enriched the Earth far earlier than currently supposed. The discovery, sure to trigger controversy, suggests life could arise earlier than thought on alien planets, too, reports livescience.com. Currently, scientists widely believe photosynthetic microbes helped oxygenate the planet roughly 2.4 billion years ago, and that oxygen was scant in the atmosphere before then. They base this idea on isotopes of sulphur in ancient rocks. Isotopes of sulphur all behave virtually the same chemically but have slightly different masses.