The Failures of Mathematical Anti-Evolutionism
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The Failures of Mathematical Anti-Evolutionism (Jason Rosenhouse) (z-lib.org)
(Moorhead and Kaplan 1967, 76)
94 4 the legacy of the wistar conference Schützenberger’s presentation is muddled, and it is not always clear precisely what he is asserting. In some places he seems to be making the modest claim that the mechanisms of development, through which the genotype is transformed into the phenotype, were very poorly understood at the time of the conference. Elsewhere, however, he seems to be making the much stronger claim that it was not even possible in principle for the genotype to determine the phenotype. For example, here is an exchange between Schützenberger and Ulam in the ensuing discussion: Ulam: My impression is that what you have said so far is that one does not understand now how the blueprint determines the existing physical objects. That, of course, the Darwinians or neo-Darwinians would freely admit. Now, the assertion that such blueprints exist and are important is made much clearer through the discovery of the genetic chains as codes. Nobody in the 19th century or even now would profess to understand the details of how, from the code, an actual organism is produced. Schützenberger: We are not worried with the details. The only thing is that I would need an example where such a correspondence would exist or could exist, even in the simpler case. (Moorhead and Kaplan 1967, 75) This ambiguity aside, I think we can reconstruct Schützen- berger’s argument like this: Evolutionary theory is fundamentally flawed because it has no account for how random changes to the genotype translate into changes in the phenotype, or even how it is possible for such a process to work. Moreover, when we try to simulate this process on a computer, we find that it fails completely. Random changes to computer programs not only do not lead to improved programs, they nearly always lead to nothing functional at all. The other attendees were entirely unimpressed by this argu- ment, for good reason. It is important to distinguish two different 4.3 genetics is different from computer science 95 questions. One question is this: What are the physical mechanisms through which the sequence of genetic letters in a genotype lead to the creation of an actual organism? Everyone at the conference agreed that those mechanisms were mysterious, and also that those mecha- nisms were relevant to understanding evolution. Had Schützenberger stopped here the discussion following his talk would have been far more harmonious. Instead he acted as though he was addressing a different ques- tion: Does our current ignorance of the mechanisms of development imply that evolutionary theory is just fundamentally unsound? The answer to that question is no. Ulam made this point well in the discussion: What you are saying, it seems to me, is that the Darwinian and neo-Darwinian theories are not complete, and everybody agrees with that; but it is not an objection to the scheme of things, which is sort of lost sight of. (Moorhead and Kaplan 1967, 76) Ulam’s point can be understood like this: It is often said that in science there are problems and there are mysteries. “Problems” are open questions that are likely to be resolved through more research of the sort that is already ongoing. “Mysteries” are open questions that seem utterly incomprehensible within the current best understanding of science. In saying that Schützenberger’s arguments were not an objec- tion “to the scheme of things,” Ulam was saying the then current ignorance of embryological development was merely a problem and not a mystery. Biologist Richard Lewontin also made some salient points dur- ing the discussion. As part of an exchange about how random muta- tions affect phenotypes, he said: [I] can give [Schützenberger] known cases where the enzyme, far from being destroyed, is changed in its pH optimum, changed in its isoelectric points, changed in a number of aspects of its physiological function by single substitutions of single amino 96 4 the legacy of the wistar conference acids. We know exactly where in the phenotypic topology of the protein these amino acids have been substituted, and we can specify exactly in what way they change the physiology of the organism, changing its fitness in the write-in space. Download 0.99 Mb. Do'stlaringiz bilan baham: |
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