Question

Can you describe the famous experiment done in the 1950’s by Stanley Miller and how it relates to the origin of life?

Stanley Miller’s idea addressed the question: what was the source of organic material (the building blocks of life) on Earth? He suggested the material was formed in Earth’s highly reducing atmosphere during electrical discharges caused by phenomena such as lightning. With that in mind, Miller and his colleague Urey designed an experiment where they passed an electrical discharge (continuous spark) through a mixture of gases thought to be present in the atmosphere of early Earth: hydrogen, methane, ammonia and water vapor. At the end of a week they found that several amino acids (‘organic material’) had formed. Currently, there are three different theories about the source of organics: 1. A descendant of Miller’s theory – organics were formed in cycles of chemical reactions in the oceans and in the atmosphere, now believed to be less reducing than was originally assumed. 2. Simple organics were delivered to Earth from space by meteors, comets and, most of all, tiny interstellar dust particles. 3. Organic molecules were synthesized deep in oceans near the so called hydrothermal vents (eruptions of hot water at high pressure from the ocean floor). Many active and inactive hydrothermal vents have been found in recent years. The relative importance of these three potential sources is unknown and remains a very active area of research in astrobiology.
May 1, 2002