(N/A) In $1953$,$S$. $L$. Miller,an American scientist,created conditions in a laboratory that were similar to the primitive atmosphere of the Earth (see diagram).
He created an electric discharge in a closed flask containing $CH_4, H_2, NH_3$ and water vapor at $800\,^oC$.
He observed that amino acids were formed in the mixture.
Similar experiments by other scientists also showed the formation of sugars,nitrogen bases,pigments,and fats.
Analysis of meteorites falling on Earth also reveals similar compounds,indicating that similar processes might be occurring elsewhere in space.
With such limited evidence,the theory of chemical evolution is more or less accepted as the first concept of the origin of life.