“RNA world” refers to a hypothetical stage in life’s origin on Earth. The term was coined in 1986 by American molecular biologist Walter Gilbert (1932–) to explain two tasks carried out by the RNA: to store information and to act as an enzyme. Gilbert proposed that these early “RNA” molecules randomly assembled together in the primordial soup, carrying out simple metabolic activities. (For more about early life on Earth, see the chapter “Basics of Biology.”)