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NY Center for Studies on the Origins of Life and Department of Chemistry, Rensselaer Polytechnic Institute, Troy, New York, 12180-3590, U.S.A., ferrij@rpi.edu
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| INTRODUCTION |
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Ten years ago it appeared that we had made good progress on understanding about when life arose and what the environmental conditions on the Earth were at that time. Carbon isotope studies on rocks present on the Earth 3.8 Ga suggested life arose in or slightly after that time period (Mojizsis et al. 1996). In addition, microfossils found in rocks dated to be 3.5 Ga suggested were consistent with the presence of life 3.5 Ga (Schopf 1993). These data have been challenged recently (Brasier et al. 2002) so it is not certain the proposed microfossils were originally living organisms. Also the carbon isotope studies have been challenged (Moorbath 2005). But new and entirely different findings suggest that that the Earth had liquid water and an environment suitable for life 4.3 Ga. (Watson and Harrison 2005). In addition it has been proposed that the early Earth had an atmosphere with a mixing
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