Today we celebrate the birthday of Stanley Lloyd Miller (7 March 1930 – 2 May 2007), the American chemist and biologist known for his experiments into the origin of life.
The most famous of his experiments was the so-called ‘Miller-Urey experiment’, where he and his research partner Harold Urey showed that it was possible, using simple chemical and physical processes, to create organic compounds from inorganic substances. This was considered a logical explanation of how organic life could have started on an planet made up of inorganic chemicals.
The famous Miller-Urey experiment, conducted in 1952 at the University of Chicago, tried to recreate the conditions existing on the early Earth before organic life existed. The experiment combined a number of chemical compounds – water, methane, ammonia and hydrogen – sealed in an connected loop of glass tubes and flasks. The first flask, containing the chemical mix, was heated to cause evaporation, and the gas was allowed to flow into a second flask where sparks (simulating lightning) were fired between electrodes installed in the flask. The ‘electrocuted gas’ was then cooled again in a subsequent flask, and the condensed liquid was allowed to trickle back into the first flask. This cycle was continued over an extended period.
After about a day, the chemical liquid was reported to turn pink, and after about 2 weeks of operation, Miller and Urey found that some of the carbon in the system had turned into organic compounds. By this stage the mixture included amino acids, sugars, bio-molecules and hydrocarbons.
The Miller-Urey experiments showed, quite compellingly, that simple organic compounds – building blocks for proteins and other organic macromolecules – could be created from basic chemical compounds with the addition of heat and electricity.
The spontaneously created brew of life-yielding organic compounds support the ‘primordial soup’ theory first proposed by Soviet biologist Alexander Oparin in 1924. Very simply stated, the theory suggests that the early Earth’s atmosphere, exposed to various forms of energy, produced simple organic compounds, which accumulated as a ‘soup’ in various locations, and through further transformations, more complex organic polymers were formed, leading ultimately to the formation of water-based organic life forms.