and How a Singularity Might Bring It Down. --FY

http://blogs.scientificamerican.com/observations/2011/09/23/...

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In Russell’s picture, the primeval Earth looked uncannily like a giant bacterium. At the seafloor, in spots like the Lost City hydrothermal vents, the chemically reduced interior met the oxidized exterior, creating a state of chemical disequilibrium. Hydrogen bubbling up from the interior sought to combine with carbon dioxide dissolved from the atmosphere to form methane, but this reaction has a bottleneck because intermediate stages such as formaldehyde require an input of energy (see this helpful graph). A geochemical reaction known as serpentinization can push through the bottleneck, using metals such as iron as catalysts, but biological reactions are more efficient, and Russell mapped out a series of steps whereby serpentinization would evolve into membrane-encased cells.

Evolution at this stage was not by natural selection, but by the spontaneous generation of complexity; the Darwinian version came later as information-bearing molecules arose. The scenario is commonly referred to as “metabolism-first” as opposed to “genetics-first.” It is the protobiological version of the principle that the way to a man’s heart is through his stomach.

The process would have given birth to two of the three kingdoms of life, bacteria and archaea. Russell suggested that life might have arisen multiple times on Earth and, indeed, on any planet with similar chemical imbalances. Phylogeny replicates geology.

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