The Oparin-Haldane hypothesis is a proposed explanation for how life first formed. According to this idea, the inorganic molecules that were present in the early atmosphere were able to form building blocks of biomolecules such as amino acids and nucleotides. These were then able to go on and form self-sustaining biomolecules, such as self-replicating RNA, and through a gradual process, eventually resulted in cells and the first life.

The Miller-Urey experiment was an experiment conducted in the 1950s, and is considered to be the classic experiment looking into abiogenesis (the idea that life first arose from nonliving molecules).

This experiment involved recreating what was believed to be the characteristics found on early Earth. Water, methane, ammonia, and hydrogen gas were present in the experiment. Water was heated to evaporate and create water vapor, which would mix with the other gases in the "atmosphere" and would be exposed to electric sparks which were meant to stimulate lightning. The experiment was set up so that the water vapor would condense back into water and then cycle back towards the heat source, where it would be evaporated and the cycle would continue.

The results from this experiment showed that amino acids could spontaneously form under these conditions, providing evidence to back up the Oparin-Haldane Hypothesis.