In 1953, Miller and Urey assembled an early earth atmosphere which consisted gases like NH₃, CH₄ and H₂S, etc. except oxygen, over water. They maintained it at the temperature just below the 100°C and passed electric sparks in the mixture of gases to stimulate lightning. This was continued about one week. After that they found that 15% carbon from CH₄ had been converted to simple organic compound like sugar and amino acids which constitute into protein molecules. This experiment gives the evidence for origin of life from inanimate matter.