The Ancient Earth

The experiment that Stanley Miller reported in 1952 stunned the world. As Miller has readily explained, however, that experiment was not the first such one he tried. Earlier he had set up his apparatus in a somewhat different manner and found that some oil was formed, but no amino acids. Since he thought amino acids would be the most interesting chemicals to find, he jiggled the apparatus around in hopes of producing them. Of course, if conditions on the ancient earth actually resembled Miller s unsuccessful attempts, then in reality no amino acids would have been produced. 

Zahnle, K. and Sleep, N.H., 2002. Carbon dioxide cycling through the mantle and implications for the climate of the ancient Earth. In Fowler, C.M.R., Ebinger, C.J., and Hawkesworth, C.J. (eds) The Early Earth Physical, Chemical and Biological Development. Geol. Soc. Lond. Spl. Publ., 199, 231-57. 

Chemical evolution concerns the chemical processes that occurred on the ancient Earth about 4.5-3.5 million years ago. It is important to note that it preceded biological evolution that resulted in the formation of protocells. These forerunners of today s living cells were capable of self-reproduction at the expense of some protometabolism. After Oparin s ideas of the origin of life became widely known and especially after Stanley Miller reported his prebiotic soup experiments in 1953, the concept of chemical evolution became accepted. 

Living matter consists of six indispensable elements, namely C, H, O, N, P, and S, and, in addition, many more trace elements, for instance, iron. These elements are capable of existing in different valence states and are thought to have predominated the ancient Earth. 

The catalytically active, Wyoming-type montmorillonites are inferred to have developed their distinctive, high-Na smectite-rich compositions following deposition of granitic volcanic ash into a shallow, saline ocean during the Late Cretaceous. Oxygen isotopic data from Hadean zircons have been interpreted as indicating that oceans may have been present on the Earth by as early as 4,300-4,400 million years ago (62-63). While current evidence provides no information on the composition of the hypothesized Hadean seawater, the existence of oceans on the Hadean Earth is a necessary environment on the ancient Earth if catalytically active montmorillonites formed. 

I am now ready to discuss the ancient Earth. At a time when the ocean was anoxic and constrained little sulfate, the oceanic crust was not a significant oxygen sink. There was little sulfate in the circulating seawater to react with the basalt and no oxygen to oxidize vented sulfides. 

Figure 11 Biomolecules on the Ancient Earth. Reference Appendix 2, Explanations to the...

The interrelationship of ancient unicellular prokaryotes to UV irradiation and calcitriol-Uke molecular metabolism is unknown. UV-Ught might have induced genomic activation (such as an elementary Hh-Uke cascade for accelerated replication), and calcitriol-Iike protective mechanisms for survival. In comparing the atmospheric conditions of the ancient Earth with the Martian situation in terms of the effects on unicellular organisms in their hydrated, metabolically active, frozen, or dried state, UV-irradiation induced mutations, DNA-repair, and resistance mechanisms [1209]. 

RNA molecular constituents adenine, guanine, cytosine, uracil form fi om for-mamide under the impacts of high energy laser imitating extraterrestrial bombardments of the ancient Earth over four billion years ago (Ferus M et al J Phys Chem 2014 118 719-736 Proc Natl Acad Sci USA 2015 112 657-662). 

Finally, this work su ests that origin of life was not a one-time historical accident but a natural and, perhaps, potentially inevitable consequence of an interplay between the solar UV-light and the geochemical conditions that existed once on the ancient Earth. 

Hence, the concentration of iron in seawater is supposed to be quite high. In fact, it is very low in the today s seawater. It is estimated to be about 10" mol/L on average. The problem is that the atmospheric composition on the today s Earth is quite different from that on the ancient Earth. Let us see why it is so. Iron, in the form of Ee(II), is soluble in neutral water, but Fe(III) is quite insoluble in water as it precipitates as the hydroxide Ee(OH)3 or EeO(OH). 

Current geochemical theory suggests that molecular oxygen was in very low concentration in the atmosphere of the ancient earth, and carbohydrates were broken down by the process of anaerobic glycolysis (reaction 1.2) to give energy in the form of adenosine triphosphate (ATP), a phosphorylated and purine-... 

The evolution of photosynthesis occurred on the ancient earth in prokaryotes, the bacteria and blue-green algae high plants evolved abruptly from prokaryotes when the heterotrophic ancestor (2 above) acquired plastids by symbiosis. 

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