From: bivalve (bivalve@mail.davidson.alumlink.com)
Date: Wed Aug 13 2003 - 13:22:21 EDT
>Doesn't it seem easier to make the claim that shell shapes were derived without intelligent intervention if the patterns are readily identifiable as essential to organismal viability rather than simply aesthetics or emergent beauty?<
I probably was too brief in my initial post.
Shell shape has many clear functional constraints and selective pressures (protection, economical use of calcium carbonate, streamlining for burrowers or swimmers, etc.), though there is also some evidence for random variation. There is also good evidence in many cases of the course of evolution bringing about the shell form.
It is definitely the case that the mollusks can build the shells without having much intelligence; the highly intelligent ones have little or no shell.
Shell color has very little known function in many cases. It has been demonstrated that having a wide variety of patterns within a species can help keep predators from forming a search image that is effective for the entire species. Some species obtain pigments from the food; if they also live on it, using these pigments can serve as camouflage. Mother-of-pearl is both pretty to us and useful to the mollusk because of its structure, as the color is an interference pattern produced by the numerous tiny stacked plates of aragonite which also produce a very strong but somewhat flexible shell.
On the other hand, many species cover the shell (with a dark protein layer, with tissue, or with algae and epifauna) and many live permanently buried; color seems useless to them. Color does not preserve well in the fossil record, though traces of the pattern often can be detected in well-preserved material (e.g., spots or stripes visible but color faded away). Thus, there is limited direct evidence about the evolution of the color patterns. In general, the color patterns may be derivable from relatively simple algorithms, but ofthen with mathematically chaotic results.
The fact that mollusks make aesthetically pleasing patterns that serve no known function for the animal could be taken as an evidence of design in the traditional sense of involving a designer with aesthetic inclinations. However, such design is not amenable to the sort of approach used by ID analyses. I think that I will never sell a poem as lovely as a shell, but Dembski is looking instead for a shell that is more complicated than the poem.
Dr. David Campbell
Old Seashells
University of Alabama
Biodiversity & Systematics
Dept. Biological Sciences
Box 870345
Tuscaloosa, AL 35487-0345 USA
bivalve@mail.davidson.alumlink.com
That is Uncle Joe, taken in the masonic regalia of a Grand Exalted Periwinkle of the Mystic Order of Whelks-P.G. Wodehouse, Romance at Droitgate Spa
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