Alien Life Might Arise Quickly, Study Suggests (SPACE.com / LiveScience.com)

Charles Q. Choi Special to LiveScience LiveScience.com Wed Aug 23, 4:15 PM ET 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 be controversial, suggests life could arise earlier than now thought on alien planets , too. 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 ...