MP Board · Class 12 · Biology · EvolutionDescribe the Miller-Urey experiment. What was its main hypothesis and what conclusion was drawn from its results regarding the origin of life?

The Miller-Urey experiment, conducted in 1953 by Stanley Miller and Harold Urey, aimed to experimentally test the Oparin-Haldane hypothesis of chemical evolution, which proposed that living organisms originated from non-living inorganic molecules under prebiotic Earth conditions. \nIn their laboratory setup, Miller and Urey recreated the reducing atmospheric conditions believed to exist on primitive Earth. They assembled a closed glass apparatus containing a mixture of gases: methane ($CH_4$), ammonia ($NH_3$), hydrogen ($H_2$), and water vapor ($H_2O$). To simulate lightning as an energy source, they generated electric discharges using tungsten electrodes at $800^\circ C$. Water was continuously boiled to circulate steam, and condensed liquid was recirculated. \nAfter running the apparatus continuously for a week, they analyzed the collected condensed fluid. The chemical analysis revealed the formation of organic monomers, particularly amino acids such as glycine, alanine, and aspartic acid. This provided experimental proof that complex organic building blocks of life could synthesize spontaneously from inorganic precursors under primitive Earth conditions.