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"I did not set out to destroy Darwinism"
|Darwinism relies exclusively on random mutations, natural selection and time to explain life. Critics try to prove that these 3 factors cannot possibly do what Darwinists claim. David Foster is one of the critics who calculated the probability of the origin of life by chance.|
In the Chapter 'Monkeys and typewriters', Foster refutes an argument he attributed to Thomas Huxley: "six monkeys typing randomly for millions of millions of years would type all the books in the British Museum." It was supposedly what Darwinists claimed about the powers of chance in evolution. It is great fun that Foster did calculate the probability: "Huxley's six typing monkeys typing for the duration of the universe would type 36 letters of sense in one of the books in the British Museum" (p57). This is caused by the extreme high number of permutations of a single line of text of 50 characters: 8.5 x 1049 (based on an alphabet of 26 letters). However Huxley could not have told the story about typewriters in 1860, because typewriters did appear 14 years later (in 1874) on the market! (11) Furthermore in 1860 it was not known that genetic information is a linear arrangement of a small number of symbols, so the whole argument could not have arisen in Darwin's time. So although Foster was wrong in attributing the argument to Huxley/1860, he correctly pointed out the computational limits of a random process producing meaningful information.
By specificity Foster means information content of proteins and DNA. Proteins contain information because there is a linear arrangement of 20 different amino-acids. The possible arrangements can be calculated and are of astronomical magnitude. The sequence of the basic elements of proteins is biological important: it enables a subclass of proteins, enzymes, to selectively speed up specific biochemical reactions resulting in increased amounts of a specific product. This idea is still central to biochemistry. However it is important to know that non-specific enzymes exists (for example some proteases). The example Foster uses is hemoglobin. It consists of a chain of 564 amino-acids. Since there are 20 possible choices for each position, a protein of only 3 amino-acids long has 20x20x20 = 8000 possible configurations. On the basis of this kind of reasoning Foster calculates the specificity as 10650. That means there are 10650 possible linear arrangements of the amino-acids, of which hemoglobin is only one. Trying out all these possibilities to find the right one takes longer than the age of our universe. Of course the sum of the specificity of all proteins of an organism is much higher. So life cannot evolve by chance, Foster concludes.
However in a postscript to the chapter Foster mentions the discovery of neutral (non-specific) amino-acids. This lowers the amount of significant amino-acids to 516 and lowers the actual specificity of hemoglobin. This is the only correction Foster permits himself. The problem with Foster's calculation is that he assumes that (1) the whole protein must be created in one step out of nothing, and (2) that the total sequence is unique and has no repeated units and (3) that each amino acid is specific and irreplaceable. These assumptions are wrong. Totally absent in Foster's attempt is any evolutionary mechanism to produce genes and proteins: mutation and natural selection. Proteins and genes are not created by throwing the dice.
The second assumption is wrong because human hemoglobin is made up of 4 subunits, two alpha subunits of 141 amino acids and two beta subunits of 146 amino acids (2). That reduces the number of unique amino-acids to 141+146=287. The fact that hemoglobin consists of sub-units also suggests a mechanism of origin: duplication and variation of sub-units.
His third error is his number of non-specific amino-acids. The hemoglobins of different species can differ as much as 81% (3). Since the whole protein is functional, only 19% of the sequence seems to be significant. What really matters is not the sequence but the 3-dimensional structure of the protein. For example hemoglobin of mouse and men match for 80% on the level of the sequence, but are identical when viewed as 3-dimensional structures (13). This lowers drastically the number of specific amino-acids and increases the probability that hemoglobin could evolve by a stepwise selection of random mutations. See also: "Did hemoglobin evolve to carry oxygen?
Foster's calculations are irrelevant for the origin of life.
To begin, proteins don't necessarily need those 20 amino acids occurring today in proteins.
There is evidence that functional proteins could be constructed from less then the current 20
amino acids. Proteins can be constructed from 8-10 different amino acids.
This lowers again drastically the number of specific amino-acids and increases the probability
that a useful protein could evolve by a stepwise selection of random mutations.
Finally, who says that life started with proteins? Why didn't life start with DNA or RNA?
How many possible oxygen
binding proteins are there?
A very important question Foster does not ask is:
what are all the possible protein-structures that also could bind oxygen?
If there were hundreds or thousands possible protein structures doing the same as hemoglobin,
than it would be much easier to produce an oxygen-binding protein by random variations.|
According to Stuart Kauffman (4) the right question is: what is the probability of finding any one of a possible set of 2000 enzymes for 2000 particular reactions, which are necessary for life? Not just the one set which happens to be found by evolution.
From recent studies in the creation of artificial proteins it appears that one does not need such a complex molecule as hemoglobin to transport oxygen: "The ease with which globin-like properties can be reproduced in a completely unrelated and simply engineered maquette indicates that the relatively complex globin fold is for the most part unremarkable, and may be common in nature not because of a uniquely capable design for oxygen binding, but simply because it is good enough." (18).
So far we have looked exclusively at proteins. However, if we turn to DNA, the situation changes dramatically. If there are millions of possible DNA sequences that encode exactly the same protein, the probability that a random DNA sequence would produce the protein would be much larger. The redundancy of the genetic code implies that a typical 300-amino-acid protein can be encoded in about 10151 ways! (17).
Did hemoglobin evolve to carry oxygen?
||There is another hidden assumption in Foster's reasoning: hemoglobin was designed for oxygen transport and it must be able to do so right from the start. However the theory that hemoglobin evolved to carry oxygen around the body may need a rethink in light of another way in which molecules related to nitric oxide, NO, released from hemoglobin, help the brain control respiration. Given the results of recent experiments, we may legitimately question whether hemoglobin first evolved to carry oxygen or to ferry NO to key locations in the body. It has been argued that hemoglobin's original task was to enable reactions involving NO and SNOs to occur, and that it's ability to carry oxygen came later. Other work supports this view (14). Hemoglobin has been found in plants(!) and even in bacteria(!) (15). Transport of oxygen cannot be the function of hemoglobin in bacteria. This is a general principle in evolutionary biology: the current function need not be the reason it evolved in the first place.|
SENSE SENSE SENSE A A C C A T A T G |________| |________| | NONSENSE NONSENSE | |________| |________| NONSENSE NONSENSE
(figure on page 74)
One example where Foster's lack of biochemical knowledge results in serious errors, is
his drawing on page 74 where he displays 3 SENSE codons,
and 4 different NONSENSE codes.
On the next page he clearly states that there are 20 codons in DNA for 20 amino acids;
40 codons for comma or full-stop effects and 4 unusable codons. However:
the genetic code is commaless and spaceless. There are no equivalents of commas and spaces
in DNA. (7)
There are no more than 3 stop-codons or NON-SENSE codes, which function as start/stop for
reading, and there are 61 codons which code for amino acids.
A surprising aspect of Foster's presentation of the genetic code is that
that particular view of the genetic code was published by
Crick, Griffith and Orgel as "Codes without commas" in 1957 and which
received an immediate and almost universal acceptance (8). A coincidence?
However the most stunning aspect is, that the hypothesis was refuted by experimental
evidence in 1961 !
So, 32 years after the discovery, Foster(1993) still believes in this refuted hypothesis.
This must imply that Foster did not touch a biology textbook since the sixties!
The discovery of the structure of DNA and of the genetic code are the central discoveries
of biology of this century and Foster misrepresents them.
Notwithstanding grave errors, Foster points to the information content of DNA and proteins and tries calculate it. The information content of proteins is one of the things one needs to know to estimate how long it will take a random trial and error process to generate it. If time is too short, the information could not be generated by a trial and error process. So the combination of a random trial and error process and the amount of time, are potential falsifiers of Neo-Darwinism. One rarely encounters this kind of approach in textbooks on evolution. (10). The concept of specificity is not explained. The approach is present in Denton (1986,page 323). However if Foster's falsification is meant to be a serious one, he has to use a 'nut-and-bolt' biochemical correctness. Foster fails to do that. He admits he is not a molecular biologist (p.60), and this affects the reliability of his conclusions negatively. But also the calculation of the information content of proteins is much better done by Hubert Yockey (9).
Foster announced that he did not set out to destroy Darwinism. On page 82 he concludes: "Darwin's theory of evolution is wrong", because "Darwin totally underestimated the time duration which such a theory would need: trillions of times longer than the existence of the universe". This proof of the impossibility of evolution reminds me of Zeno's convincing proof of the impossibility of movement (5). How impressive the proof may be, we simply observe movement, so there must be something wrong with Zeno's argument.
I found another 'impossibility' in Ian Stewart (12). A protein is a linear chain of amino acids, which has to be folded to work. To determine the optimal fold is called 'the protein-folding problem'. Mathematicians estimated that the calculation of the optimal fold for cytochrome-c would take about 10127 years on a supercomputer. Longer then the age of the universe. Impossible. The funny thing is that living organisms can fold a protein containing a thousands amino acids in about a second. So there must be something wrong with the calculation.
CONCLUSION: I reject Foster's calculation because the calculation is not realistic. It ignores biochemical knowledge and is based on an imaginary mechanism (dice). Darwinism survived another impossibility: that of Lord Kelvin's claim that the age of the earth was too short for evolution to occur, which turned out to be wrong (6).
|Is DNA programmed from the sun?||
This is the title of a weird chapter in The Philosophical
Scientists. It is Forster's solution
to the problem where the huge amount of information in DNA is coming from:
beaming information by gamma radiation from the sun. I sum up only a few
of the problems his 'solution' faces.
Is the receiving organism just an empty cell with no DNA at all? In any case a recording mechanism is needed to receive and translate the information into DNA-sequences and to incorporate the sequences into chromosomes. A major problem with this hypothetical mechanism is a vicious circle: if the 'receiver-mechanism' is also coded by DNA (and how could it be otherwise?), how did that DNA get into the organism? This mechanism does not exist (anymore!) in today's organisms. So a designer should have constructed the mechanism and destroyed it after the information was received. This is a weird way to provide genetic information to organisms. The Designer could as easily put the information right away into the organism: Let There Be DNA! There are also 'minor' problems: how to focus the message to the right organism? How does a proto-organism know which information is meant for it? If there is a continuous flow of information: when to start recording? When to stop? What about organisms that live in total darkness? How could information be stored in the sun anyway? Why was the information in the sun not used for giving birth again to the millions of extinct species?
Foster's book is unfinished. There is no index and no bibliography. Foster uses postscripts to chapters, in stead of integrating it in the chapter. The book could have been improved if he had discussed the chapters on DNA and hemoglobin with a molecular biologist before committing them to print. The Philosophical Scientists is a serious error of Barnes & Noble.
|About the author: David Foster, now (1993) retired from a career as a scientific consultant, received his technical training at King's College London and has the degrees of M.Sc. and Ph.D. This is his seventh book.|
This book was a gift from Sid King
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|Copyright © 1997 G.Korthof||First published: 12 Sep 1997||Last update: 19 Mar 2009|