The theory of chemical evolution rests upon three assumptions:
1) The hypothetical primitive atmosphere must have been either reducing or neutral. This means that there was no free oxygen in the atmosphere in the earth’s distant past.
2) Simple molecules like amino acids, purines, pyrimidines and sugars were formed within this atmosphere under the action of ultraviolet radiation, electrical discharges, radioactivity, thermal energy and so on.
3) In the course of time, these molecules gave rise to proto-proteins, protonucleic acids and other protocellular components, which in turn gave rise to the so-called protocells and finally to the living cell.
We can briefly analyze these assumptions by purely scientific reasoning and argument. It is a foregone conclusion of many molecular evolutionists that the primitive atmosphere consisted of carbon in the form of hydrocarbon, such as methane, nitrogen in the form of ammonia, oxygen in the form of water and sulfur in the form of hydrogen sulfide. This was first proposed by Oparin, the Russian evolutionist, and Urey, the American physicist.
Based on this assumption, Miller performed an experiment in 1953 in which he passed an electric discharge through a gaseous mixture of methane, ammonia, hydrogen and water vapor. Amino acids such as glycine, alanine, aspartic acid and glutamic acid were observed as some of the components of the reaction products. Since amino acids are the smallest units of the protein molecule, Miller’s experiment gave the molecular evolutionists great hope and encouragement for their idea of the chemical origin of life. They claim that such steps are the ones that will finally lead to life. However, in the light of many experimental findings, such a claim is far from truth. It is just the wishful thinking of the chemical evolutionists.
The idea of the primitive reducing atmosphere has received strong and serious criticisms from scientists of various disciplines. Their arguments suggest overwhelming drawbacks in the conjecture. Available data from geology, geophysicists and geochemistry argue strongly against this idea. Abelson, for example, argues that there is no evidence for the reducing atmosphere, and that ammonia would have quickly disappeared because the effective threshold for degradation by ultraviolet radiation is 2,250Ã…. He suggests that a quantity of ammonia equivalent to the present atmospheric nitrogen would be approximately 30,000 years.
Abelson has also suggested that if the primitive atmosphere contained large amounts of methane gas, geologic evidence for it should be available. Laboratory experiments show that irradiating a highly reducing atmosphere produces hydrophobic organic molecules that are absorbed by sedimentary clays. This suggests that the earliest rocks should have contained an unusually large proportion of carbon of organic chemicals. However, this is not the case.
From observations based on the stratigraphical record, Davidson concludes that there is no evidence that a primeval reducing atmosphere might have persisted during much of Precambrian time. Brinkmann shows from theoretical calculation that dissociation of water vapor by ultraviolet light must have generated enough oxygen very early in the history of the earth to create an oxidizing atmosphere.
Besides these, there have been huge numbers of other arguments and findings against primitive reducing atmosphere. Recently, many geo-scientists have also expressed great doubt about it. In light of these arguments, the idea of a primeval reducing atmosphere does not seem tenable.