Enough Oxygen for Life Found Millions of Years Earlier in Geologic record

[n2doc]

By Lisa Grossman November 10, 2010

Earth’s atmosphere contained enough oxygen for complex life to develop nearly 1.2 billion years ago — 400 million years earlier than scientists previously believed.

The findings, reported in the Nov. 11 Nature, could lead scientists to reconsider the prerequisites for animal life, on Earth and other planets.

“It means that the conditions were in place for complex life to arise,” said geologist John Parnell of the University of Aberdeen in Scotland, lead author of the new study. “There might be animals in that earlier window that we have not yet found.”

Geological records show there was one major increase in the amount of oxygen in Earth’s atmosphere around 2.3 billion years ago, and another around 800 million years ago.

That second spike in oxygen levels was thought to be connected to the Cambrian explosion, the swift development of most of the major animal groups that came around 550 million years ago.

http://www.wired.com/wiredscience/2010/11/early-earth-oxygen/