"... 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.' He went on to explain that 'at the present day such matter would be instantly devoured or absorbed, which would not have been the case before living creatures were formed.' In other words, the presence of life itself makes the search for the origin of life dependent on the sterile conditions of the laboratory."
"... J. B. S. Haldane suggested that the Earth's prebiotic oceans-different from their modern counterparts-would have formed a 'hot dilute soup' in which organic compounds could have formed. This idea was called biopoiesis or biopoesis, the process of living matter evolving from self-replicating but nonliving molecules. ... In 1952, in the Miller-Urey experiment, a mixture of water, hydrogen, methane, and ammonia was cycled through an apparatus that delivered electrical sparks to the mixture. After one week, it was found that about 10% to 15% of the carbon in the system was now in the form of organic compounds, including amino acids, which are the building blocks of proteins. The underlying hypothesis held by Oparin and Haldane was that conditions on the primeval Earth favored chemical reactions that synthesized organic compounds from inorganic precursors."