He suggested that the original spark of life may have begun in a `` warm little pond , with all sorts of ammonia and phosphoric salts , lights , heat , electricity , etc. . A protein compound was then chemically formed ready to undergo still more complex changes '' .
In a letter to Joseph Dalton Hooker on February 1 , 1871 , Charles Darwin addressed the question , suggesting that the original spark of life may have begun in a `` warm little pond , with all sorts of ammonia and phosphoric salts , lights , heat , electricity , etc. present , so that a protein compound was chemically formed ready to undergo still more complex changes '' .