S.L. Miller created an environment in a laboratory similar to the one that existed before life originate. In a closed flask containing CH4, H2, NH3 and water vapour at 800o C, electric discharge was created. The conditions were similar to those in primitive atmosphere. After a week, they observed presence of amino acids and complex molecules like sugar, nitrogen bases, pigments and fats in the flask. This provided experimental evidence for the theory of chemical origin.
