Thursday, 9 April 2009

Ancient nickel famine may have birthed complex life

Almost 3 million years ago, a subtle geochemical change in volcanic lava may have set the stage for complex life to evolve.

According to geologist Mark Barley, nickel levels in lava and in the sea water began to drop approximately 2.7 million years ago, decreasing by more than half within the subsequent 200,000 years.

Decreased nickel levels were detrimental to the methane-producing microbes that inhabited Earth at the time, paving the way for the proliferation of oxygen-producing bacteria that eventually oxygenated the atmosphere.

"Methane-producing microbes, [which are called] methanogens, require the element nickel for their life and for the formation of methane," explained Barley, who is a professor in the University of Western Australia's School of Earth and Environment.

“The nickel crash after its early boom 2.7 billion years ago helped make our planet habitable by complex life,” he said.

Barley and his colleagues say their findings could explain the puzzling 'Great Oxidation Event' that led to a dramatic rise of oxygen in Earth's atmosphere approximately 2.4 billion years ago.

The researchers' report was published today in the international weekly journal, Nature.

More information is available from the Carnegie Institution's press release.

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