The Failures of Mathematical Anti-Evolutionism
participants. Most notably, the aforementioned Stanislaw Ulam made
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The Failures of Mathematical Anti-Evolutionism (Jason Rosenhouse) (z-lib.org)
participants. Most notably, the aforementioned Stanislaw Ulam made the following comment at the start of his own presentation: [I] believe that the comments of Professor Eden, in the first five minutes of his talk at least, refer to a random construction of such molecules and even those of us who are in the majority here, the non-mathematicians, realize that this is not the problem at all. A mathematical treatment of evolution, if it is to be formulated at all, no matter how crudely, must include the mechanism of the advantages that single mutations bring about and the process of how these advantages, no matter how slight, serve to sieve out parts of the population, which then get additional advantages. It is this process of selection which might produce the more complicated organisms that exist today. (Moorhead and Kaplan 1967, 21) This is well said, and it largely vitiates Eden’s argument. 4.3 genetics is different from computer science While Eden was relatively understated in making his case, Schützen- berger was far more assertive. He opened by saying, “Our thesis is that neo-Darwinism cannot explain the main phenomena of evolution on the basis of standard physico-chemistry,” and he closed by saying, “[W]e believe that there is a considerable gap in the neo-Darwinian theory of evolution, and we believe this gap to be of such a nature 92 4 the legacy of the wistar conference that it cannot be bridged within the current conception of biology.” (Moorhead and Kaplan 1967, 73) If you are going to talk like that, you had better have a mighty good argument to back it up! Schützenberger based his conclusions on two observations. The first was that evolutionary theory posited a connection between what he called “typographic” changes in genotypes and observable features of phenotypes. The term “typographic” is metaphorical in this context. We certainly are not thinking about a literal typewriter. Rather, Schützenberger’s intent was that we are thinking about a genotype as a sequence of letters, and that mutations can be thought of as changes to those letters. The second was that when random typographic changes were made in computer programs, the result was usually an entirely nonfunctional program. He presented his challenge as follows: According to molecular biology, we have a space of objects (genotypes) endowed with nothing more than typographic topology. These objects correspond (by individual development) with the members of a second space having another topology (that of concrete physico-chemical systems in the real world). Neo-Darwinism asserts that it is conceivable that without anything further, selection based upon the structure of the second space brings a statistically adapted drift when random changes are performed in the first space in accordance with its own structure. We believe that it is not conceivable. In fact, if we try to simulate such a situation by making changes randomly at the typographic level (by letters or by blocks, the size of the unit does not really matter), on computer programs we find that we have no chance (i.e. less than 1/10 1000 ) even to see what the modified program would compute: it just jams. (Moorhead and Kaplan 1967, 74–75) To see what Schützenberger had in mind, imagine a recipe for chocolate chip cookies. Over here we have printed instructions telling 4.3 genetics is different from computer science 93 us what to do. By carrying out the steps of the recipe, we end up with the actual cookies to be eaten. If we make random changes to the recipe’s instructions, we are likely to produce no edible cookie at all, or at best a vastly inferior cookie. Likewise for the blueprints of a building. The blueprints can be seen as instructions for assembling the building. As with the cookie, we have assembly instructions on the one hand, and a finished object on the other. Random changes to the instructions are likely to have a deleterious effect on the finished building, to put it mildly. And likewise for Schützenberger’s computer programs. You have coded instructions on the one hand, and whatever the program does on the other. Random changes to the code nearly always produce something worthless. Not only do you not get a functional program, you do not even get anything meaningful. But according to evolutionary theory, the argument continues, random changes to genetic instructions somehow lead to meaningful change at the level of actual organisms. This is what is said to be inconceivable. In the discussion following his talk, Schützenberger said this: [I]n order to mediate between the space of chains of amino acids and the real world of organisms, some new construct has to be introduced, and principles have to be stated explicitly explaining how this mediation is conceivable. At the level of molecular biology, we are told that we have a reasonably complete description of the mechanisms. Also, physiology is providing us with an understanding of organs. However, everybody seems to take for granted that there is no gap in between. I am not discussing the adequacy of each of the two extremes. I just point out that nobody seems to be able to give reasons why they have anything to do with each other. If there were explicit general principles, then we should be able to simulate something analogous, and we would have a lot of fun studying mathematical models showing the passage from disorder to order. Download 0.99 Mb. Do'stlaringiz bilan baham: |
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