title: Chemical evolution: the first stages.
mesh_terms: D000596:Amino Acids; D000641:Ammonia; D005557:Formaldehyde; D006856:Hydrogen Cyanide; D014466:Ultraviolet Rays
chemical_list: D000596:Amino Acids; D005557:Formaldehyde; D006856:Hydrogen Cyanide; D000641:Ammonia