View Full Version : Oxygen Levels on Earth Rose Gradually

2005-Dec-05, 08:09 PM
SUMMARY: The rise of complex life on Earth matches the appearance of oxygen in the atmosphere, and new evidence from University of Maryland scientists suggests that the increase was more gradual than previously believed. According to microbial evidence, oxygen first appeared in our atmosphere 2.4 billion years ago, and a second large increase started 1.3 billion years ago, and reached its current levels about 600 million years ago.

View full article (http://www.universetoday.com/am/publish/ancient_oxygen_levels_gradually.html)
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2005-Dec-06, 09:41 AM
Photosynthesis, in a word. Oxygen is plant flatulance. I think oxygen levels first peaked anywhere from 3-4 billion years ago. I'm not surprised by the evident fluctuations in the fossil record. Earth was still in the shooting gallery phase of its development until about 500 million years ago - which shows just how robust and stubborn life can be once it secures a foothold, IMO.

2005-Dec-06, 03:52 PM
Has anyone penned up a bunch of anerobes at various levels of oxygen concentration to study tolerance levels over various levels of concentration stasis? Are they more likely to evolve (adapt) or go extinct as the O2 levels increase? How important are the rates of increase and the lengths of the periods of stasis? Can they be made to evolve in their own "oxygen pollution"?