In their famous 1952 experiment, Stanley Miller and Harold Urey observed the abiotic synthesis of amino acids, organic acids, and other organic molecules, including adenine, a building block of DNA and RNA.

Their experiment simulated the conditions of early Earth, with a mixture of methane, ammonia, hydrogen, and water vapor, and exposed it to electrical discharges. The resulting mixture contained a variety of organic molecules, demonstrating that the building blocks of life could have formed under the conditions present on the early Earth.