Plants Kick-Started Evolutionary Drama of Earths Oxygenation

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Plants Kick-Started Evolutionary Drama of Earth's Oxygenation

ScienceDaily (Oct. 8, 2010) â€" An international team of scientists, exploiting pioneering techniques at Arizona State University, has taken a significant step toward unlocking the secrets of oxygenation of the Earth's oceans and atmosphere...

...The data Dahl obtained at ASU reveal that there were at least two stages of oxygenation during the Phanerozoic, separated by the oxygenation event 400 million years ago. This inference from molybdenum isotopes is corroborated by the appearance of large (up to 30 feet long) predatory fish in the fossil record 400 million years ago, coincident with the rise in oxygen. Animals of that size consume energy rapidly, requiring high levels of oxygen for their metabolism. "Tais's data indicate that early animals evolved in an environment with less oxygen than today," said Anbar. The newly discovered oxygenation event therefore explains the puzzling appearance of these fish in the fossil record. "It's always satisfying when we can demonstrate how an environmental change drove biological evolution," Anbar explained...

Atmospheric changes have had a profound effect on life throughout history and will probably continue to do so.

[tymygy]

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In their book "The Life and Death of Planet Earth", Ward and Brownlee describe how the first wave of oxygenators essentially polluted the planet with oxygen and sowed the seeds of their own doom. For the greater oxygen concentration allowed the evolution of worms that began systematically devouring the oxygen-producing organisms. Just like a 1950s monster movie, where our nemesis arises from our own trash.

Seriously, what I love about that story is that is shows how without plan everything is. We can't just assume that everything will keep moving along hunky-dory, because the universe isn't evil, it's just indifferent. We are our only hope.