Primordial Soup Evolution

Meteorites

Some meteorites contain organic carbon, and several of these have been analyzed for amino acids. This analysis has shown that the amino acids, glycine and alanine, are quite common in some meteorites. Most of the other amino acids used by life are rare, but some are present. In addition, many amino acids not used by life are present. More than 50 non-biological amino acids are found in the Murchison meteorite.

   Meteorites are easily contaminated by biological amino acids. So samples are always taken from the meteorite interior. Unfortunately, contamination is still a major problem. Nevertheless, several generalizations are possible.

•    The biologically relevant amino acids in meteorites are always predominantly glycine and alanine. Sometimes aspartate and glutamate run a close second, but in many cases, this appears to be the result of contamination. Serine and valine are sometimes present. The other amino acids used by life are absent.

•    Non-biological amino acids are common in variety and in number. The most common non-biological amino acids are the many isomers of aminobutyric acid. The second most common non-biological amino acids are two forms of alanine that life does not use.

One comparison of four different meteorites that contain amino acids revealed that only 25% of the amino acids are biologically relevant.⁴ Because only 25% of the amino acids in the soup are biologically relevant, even if a way is found to make the amino acids join together, the odds of a protein emerging are very small.


   The average protein in the Swiss Prot database contains 362 amino acids, and most contain more than 150 amino acids. If the composition of amino acids in the soup is similar to that of meteorites, what is the probability of creating a peptide composed of 150 amino acids if all of the amino acids must be biological?

   Each addition to the growing chain has a 25% chance of being an amino acid used by life. So each amino acid added to the chain has a 1 in 4 chance of being correct. Thus, there are 4 possible outcomes and only one is desirable. Using equation 1 in chapter 1, 2^information = 4/1, and because 2² = 4, the information content for each amino acid added is 2 bits. So a random chain of 150 amino acids that emerges from the soup will contain 300 bits of information! The odds of this arising by chance are 1 time in 2³⁰⁰ tries or a 1 in 2 x 10⁹⁰ chance.

   Note that this is a special case. Sometimes information can be related to a probability. Before self replication, natural selection by definition does not exist. Thus, before life, information can be safely related to a probability.

   Also notice that the term information not knowledge is used to describe this evolution. In general, random sequences do not contain knowledge, so the term information is more appropriate.

   What do odds like 1 in 2 x 10⁹⁰ really mean? The number 10⁹⁰ is so large that naturalistic explanations will always fail to explain any event whose odds are this poor.

  

   To understand why, assume that there are 1 x 10²³ stars in the universe, and that every single star has 1 earthlike planet. Assume that all of these planets are composed entirely of amino acids (that is no iron, water or silicon - only amino acids). Further assume that every amino acid exists in a peptide chain composed of 150 amino acids. If these 1x10²³ planets are about the size of earth, then on average each has a mass of 6x10²⁴ Kg. This means that a planet composed entirely of the amino acid glycine will be composed of 5 x 10⁴⁹ glycine molecules. If all the planets have the same number of amino acids, then there will be 5x10⁷² amino acids in the universe. Since every amino acid exists in a chain of 150, there will be 3.3 x10⁷⁰ peptide chains. The odds that 1 of these chains will contain only biologically relevant amino acids is only 1 in 6 x10¹⁹. So further assume, that all of these peptide chains break down each year only to reform, and that this process has been going on every year since the inception of the universe. The odds improve to 1 in 12 billion. So while the odds are not zero, they might as well be. Nature simply cannot accumulate enough tries to overcome the poor odds.

   One can certainly speculate that the first proteins used amino acids that are no longer used today or that these proteins were very short. Both assumptions improve the likelihood for evolution. Nevertheless, all readers need to realize that when a scientist in the lab mixes together pure amino acids that are only used by life, the scientist is adding so much information to the system that the experiment can no longer be considered representative of the conditions on the early earth. The starting point for such experiments is not plausible.

   If the soup existed, then the first proteins evolved in a soup that contained many amino acids not used by life. The soup also contained a host of other chemicals like aldehydes that react readily with amino acids. These undesirable side reactions make the evolution of information in the primordial soup very difficult to explain. When a scientific experiment models evolution by excluding these other chemicals, the experiment no longer models the origin of life. Such experiments only model evolution in a test tube.

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