Actually, there's no theoretical problem with the evolution of a system that is composed of a number of interworking parts, all of which are required for the system to work at all, and none of which are useful apart from their role in the system.
All you need to remember is that in evolution, the parts themselves are as subject to modification as anything else. Evolution only rarely works by adding or subtracting parts. The most common form of evolutionary change is the modification of parts, and this is completely ignored in the ID defense of the idea that IC presents any kind of difficulty for evolution.
Consider a system which involves a number of interacting parts, so that the removal of any part only degrades the performance of the system, without removing the function entirely. This is not IC, by the definition proposed.
Now let this system be subject to evolution. Each of the parts may be subject to small changes in how it works and interacts with other parts. Furthermore, the context in which selection is applied is one where all the parts are in place. There's no selection for a part to operate independently of the others, and there can be strong selection for a small change to a part so that it works a bit better, but in such a way that its operation relies crucially on the presence of other parts. Indeed, this kind of change is precisely what one should expect. The result of such changes is to introduce new dependencies between the parts that are all ready present, so that after a time the system DOES become IC, all by perfectly normal evolutionary processes.
The earliest plain description of "irreducible complexity" was actually called "interlocking dependency", but the meaning is exactly the same... all parts are required for the operation of the system. This description was given in 1918 by Herman Muller, who went on to win the Nobel prize in 1946 for his work on mutations.
The major difference with later and much less competent analysis is that Muller presents irreducible complexity as an
expected consequence of conventional evolutionary processes; not as a problem. It is only seen as a problem with a stunted strawman of the processes of evolutionary change, as "adding and removing parts". With the more common evolutionary step of modifying parts, IC falls out very naturally as an expected consequence.
Reference:
- Muller, H. J. (1918) http://www.genetics.org/content/vol3/issue5/index.shtml , in Genetics, Vol 3, No 5, Sept 1918, pp 422-499.
The description from this paper of interlocking complexity (irreducible complexity) is as follows (with emphasis as in Muller's original!):
... Most present day animals are the result of a long process of evolution, in which at least thousands of mutations must have taken place. Each new mutant in turn must have derived its survival value from the effect which it produced upon the "reaction system" that had been brought into being by the many previously formed factors in cooperation; thus a complicated machine was gradually built up whose effective working was dependent upon the interlocking action of very numerous elementary parts or factors, and many of the characters and factors which, when new, where originally merely an asset finally become necessary because other necessary characters and factors had subsequently become changed so as to be dependent on the former. It must result, in consequence, that a dropping out of, or even a slight change in anyone of these parts is very likely to disturb fatally the whole machinery; ... [/color]
Note carefully how this arises. It occurs because of the changing of parts so that they now depend on other parts.
Cheers -- sylas
