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Author
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Topic: Pre-Adaptation: Evidence of Design?
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John Bracht
Member
Member # 5
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posted 28. April 2002 21:27
Reading Christian Schwabe, I came across the following discussion about the transition between single-celled organisms and multicellularity:
quote:
The phenotypes of the Quaternary (our period) are so different from the Cambrian creatures, it is argued by Darwinists, that only a long time of adaptation, fine-tuning so to speak, by natural selection would have converted them into all subsequent species. One must object to that proposition on the following grounds: As the Precambrian stem cells burst onto the animal scene they brought along from the single-cellular (or colony) stage their appendices, sensory and reproductive organs, their feeding machinery, and armor for protection. But since these features, save reproduction, are without meaning in single-cellular life from which the animals just emerged, their appendages could not have been adaptations to any need for defense that multi-cellular life forms developed purportedly to deal with each other. What kind of evolutionary pressure would have prepared single-cellular organisms for what lay one short step ahead of them once they transgressed the line to multi-cellularity?
This question nicely illustrates the difficulty in accounting for multicellularity from a neoDarwinian viewpoint. The problem is that there is no gradual route to a multicellular organism. Multicellularity either is, or it isn't; there is no in-between. Furthermore, certain adaptations are needed immediately once an organism is multicellular that simply were not meaningful for a single-celled organism. Therefore, there is no way for the single cell to prepare for its transition to multicellularity; there is no selective advantage to having the genes for a circulatory system, or a respiratory system, or arms and legs, if you have no need of any of these. Further compounding the problem is the sheer number of essential changes that must be coordinated for multicellularity. For it is not enough just to get the genes for limb structure (assuming they arise by chance); you must also get the genes for cell-to-cell signalling pathways that make embryonic development possible, and the various specialized adhesions and recognition molecules that go with the process. You need feeding machinery and a new reproductive system that is spread among many different cells and organs. And all these must spring forth in that single, dramatic step from single cell to multicellularity. As Schwabe points out, there is no conceptual pathway that would allow the organism to build up this genetic complexity before it is of any use. And simply postulating that it appeared miraculously at the transition doesn't satisfactorily answer the question. There are vague gestures in neoDarwinian theory toward "pre-adaptation" where chance events from earlier stages are taken advantage of in later stages; of course, nothing accounts for the breathtaking sweep of the changes that would be required here.
Thus, I propose that ID theorists begin looking carefully at these "pre-adaptation" events that require huge amounts of coordinated change and seem to "see ahead" to the next step. The only causal explanation that can see ahead to the next step is intelligence. Thus, places where the Darwinist invokes pre-adaptation may be tacit admissions of a failure in the theory; instances where an intelligent designer has intervened either directly or through a process of front-loading. I suspect that some amazing insights await a careful re-analysis of pre-adaptation through the framework of intelligent design.
John Bracht
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Mike Gene
Member
Member # 149
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posted 28. April 2002 23:24
I've always thought that terms like "pre-adaptation" and "convergence" were labels that masked a strong teleological undercurrent behind this concepts. The next few years will be very interesting to teleologists, even if we ignore the ID community. Morris will be drawing deserved attention to convergence, Shapiro continues to refine his concepts that highlight smart cells and smart evolution, and now Schwabe is drawing attention to phenomena that lend themselves perfectly to front-loading.
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