Constructing life

Any recipe for life on Earth requires a source of essential elements, a source of energy to stimulate chemical reactions between these elements, and time for these reactions to take place.

In 1952 researchers at the University of Chicago took a mixture of ammonia, methane, and hydrogen to simulate the early Earth atmosphere and applied a spark to simulate a natural source of energy-lightning-and after 8 days found that amino acids—the building blocks of DNA-- had formed in this oxygen-free atmosphere.

In the half-century since this experiment scientists have modified their ideas about the composition of the early earth atmosphere, but the Miller-Urey experiment still stands as the first example of synthesizing organic compounds from inorganic precursors—a process that occurred in the Early Earth in some form, as our own existence is evidence that it happened.

For more on the Miller/Urey experiment, see this site.