stromatolites in the Siyeh Formation, Glacier National Park. In 2002, William Schopf of UCLA published a controversial paper in the scientific journal Nature arguing that geological formations such as this possess 3.5 billion year old fossilized algae microbes. If true, they would be the earliest known life on earth.]] In the natural sciences, abiogenesis, the question of the origin of life, is the study of how life on Earth might have emerged from non-life. Scientific consensus is that abiogenesis occurred sometime between 4.4 billion years ago, when water vapor first liquefied,Simon A. Wilde, John W. Valley, William H. Peck and Colin M. Graham, Evidence from detrital zircons for the existence of continental crust and oceans on the Earth 4.4 Gyr ago, Nature 409, 175-178 (2001) and 2.7 billion years ago, when the ratio of stable isotopes of carbon (^12C and ^13C ), iron and sulfur poin

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