David
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Member # 1223
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posted 25. March 2004 12:40
On one of his essays, Dr. William Dembski (http://www.designinference.com/documents/2004.01.Irred_Compl_Revisited.pdf, page 7), said "It follows that Darwinian evolution can produce an irreducibly complex system that serves a given basic function only by taking already existing systems that serve different functions and redeploying them to form the irreducibly complex system. But, as we shall see later in this essay, there is no evidence that the redeployments required to form such irreducibly complex systems could happen, much less be properly coordinated, by a gradual Darwinian evolutionary process. Instead, the evidence suggests that any such redeployment would require such massive coordination of the redeployed systems as to place the resulting irreducibly complex system beyond the reach of Darwinian evolution. Of course, such massive coordination bespeaks design."
I have found two fairly recent papers that speak to the possibility of redeployment in systems that may meet Behe's criteria for irreducible complexity. I am interested to know what you make of them.
1. "Whole-Genome Analysis of Photosynthetic Prokaryotes" by Jason Raymond, Olga Zhaxybayeva, J. Peter Gogarten, Sveta Y. Gerdes, Robert E. Blankenship, Science, 22Nov02, p. 1616, which describes horizontal gene transfer in photosynthetic systems.
According to a report announcing Blankenship's article (http://www.asu.edu/asunews/sci_tech/photosynthesis_112602.htm), "the analysis by Blankenship's team revealed clear evidence that photosynthesis did not evolve through a linear path of steady change and growing complexity but through a merging of evolutionary lines that brought together independently evolving chemical systems - the swapping of blocks of genetic material among bacterial species known as horizontal gene transfer."
The report about the research says "Blankenship says nature's way of creating useful and complicated chemical systems through horizontal gene transfer also points to how human-directed biodesign might co-opt the process. "This work gives us some insights into how complex metabolic pathways originated and evolved, so this might give some ideas about how to engineer new pathways into microorganisms," he said. "These organisms could be designed to carry out new types of chemistry that may benefit mankind, such as multi-step synthesis of drugs."
To me, it is interesting that the possibility for human-directed design follows from the elucidation of naturally occuring evolutionary mechanisms proposed for this system.
2. "The puzzle of the Krebs citric acid cycle: assembling the pieces of chemically feasible reactions, and opportunism in the design of metabolic pathways during evolution." Melendez-Hevia, Enrique; Waddell, Thomas G.Cascante, Marta. Journal of Molecular Evolution (1996), 43(3), 293-303.
The following was adapted from the abstract (edited for length and context):
"The authors analyzed the Krebs cycle as a problem of chemical design. The analysis demonstrated that although there are several different chemical solutions to the problem, the design of this metabolic pathway as it occurs in living cells is the best chemical solution. It has the least possible number of steps and it also has the greatest ATP yield. A study of the evolutionary possibilities of each one, taking the available material to build new pathways, demonstrated that the emergence of the Krebs cycle has been a typical case of opportunism in molecular evolution. These results show that the role of opportunism in evolution has converted a problem of several possible chemical solutions into a single-solution problem, with the actual Krebs cycle demonstrated to be the best possible chemical design. The results also allow the authors to derive rules under which metabolic pathways emerged during the origin of life."
To me, it is interesting that the analysis was undertaken from a perspective of design, and concludes that what is found in nature is the most efficient solution to the problem.
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These papers seem to suggest that photosynthesis and the Krebs cycle (irreducibly complex systems?) are within the reach of Darwinian evolution. As one who accepts Intelligent Agency in Creation, I am interested to know if these examples, assuming the science behind them is sound, can be shown to be compatible with ID theory.
How do you interpret these findings?
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