Many scientists think that life appeared on earth when the atmosphere, instead of being its present mixture of oxygen, nitrogen and carbon dioxide, contained methena, ammonia and hydrogen. These ingredients, still to be found in the atmospheres of Jupiter and Saturn, slowly combined into larger and larger organic (carbon-containing) molecules, according to the hypothesis. At last one molecule, a complex protein, showed the ability to absorb other molecules and create replicas of itself out of their material. This "Adam molecule" was the first life; it could grow and reproduce itself.
When Nobel Prizewinner Harold Urey Jaborated on this theory last year (TIME,...
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