The hydrothermal source of energy and materials at the origin of life

The case is presented that chemosynthetic life emerged at the growing exterior of a submarine hydrothermal mound generated where effluent from an alkaline hydrothermal convection cell interfaced a mildly acidic ocean across a precipitated membrane over 4 billion years ago. At first a small portion of the carbonic ocean water entrained in the submarine convection cell feeding the mound was reduced at very slow rates to acetate and methane. Deposits of porous iron-nickel sulfides, freshly precipitated in the mound, further catalyzed these reactions. At the same time, amino acids and peptides, generated in this milieu from hydrothermal hydrogen, ammonia and carbon dioxide, were retained in the mound's pores. These peptides then sequestered the ironnickel sulfide clusters to produce protoenzymes that further 'quickened' the acetate and methane reactions. RNAs generated in the system then took over a catalytic and coding role to help drive the emergence of the first microbes—the acetogens and the methanogens, which evolved into the first bacteria and archaea respectively