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, Mov. 24), he said that one of his students
s checking it experimentally. Last week's Science carried the promised report. Graduate Student Stanley L. Miller, 23, told how he had simulated conditions on a primitive earth and created out of its atmospheric gases several organic compounds that are close to proteins.
Miller set up a closed apparatus containing water, methane, ammonia and hydrogen. When the water was heated, its vapor circulated the other gases past a small electric "corona" discharge, which promoted chemical reactions among their molecules. This sort of thing may have happened on the primitive earth, where lightning was probably common. In any case, the influence of the electric discharge was similar to that of the strong, solar radiation beating down on the top of the primitive atmosphere.
When the apparatus had run for a day, the water grew pinkish, then turned red. After a week. Student Miller analyzed the mixture. It proved to contain at least three amino acids (glycine, alpha-alanine and beta-alanine). This was the hoped-for payoff: amino acids are the building blocks of which proteins are made.
Professor Urey and Student Miller do not believe that they have created life. What they have done is to prove that complex organic compounds found in living matter can be formed, by chemical reactions, out of the gases that were probably common in the earth's first atmosphere. If their apparatus had been as big as the ocean, and if it had worked for a million years instead of one week, it might have created something like the first living molecule.