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12-26-2006 1:55 AM
The creationist argument about information theory often relies on the analogy of DNA with language. It is often phrased such that things like languages which contain information cannot come from random processes, they must be designed. Rather than refer to examples that show an information increase during evolutionary processes, or argue about a definition of information, I would like this thread to be focused on a simple point: DNA is not a typical language.
An biotech website has expanded the analogy between DNA and language in the following way (http://www.accessexcellence.org/RC/AB/BC/Speaking_Language_rDNA.html)
Letters: Nucleotide Bases
I tend to agree with this analogy, only adding in that exons act as periods. For clarification, a codon is a set of three nucleotide bases which codes for an amino acid. A gene is a series of codons which produces a string of amino acids, or a protein. A protein is a molecule which performs various functions. (These are layman definitions)
DNA is a language with 4 letters (ACGT), meaning that there are 4^3 different words or codons that can be made, or 64 different words. Let me also point out that each codon refers to an amino acid, except for the exons.
Many creationist arguments procede as follows. Take a word, like
Perform some random substitution:
Now you have something which is nonsensical, it has lost meaning and is not readable.
In these cases, what is being performed is a point mutation, a substitution of a single nucleotide base for another. Let's carry the analogy. Say we have this codon:
It codes for Threonine. By a point mutation, we get.
which codes for Alanine. http://www.geneticengineering.org/chemis/Chemis-NucleicAcid/RNA.htm This link has a chart that gives a complete list of how codons code for amino acids.
In other words, we imposed a random change in the codon, and meaning is still preserved. The important point is that this was not a carefully chosen example. All words or codons contain meaning in the language of DNA: a point mutation can never produce meaningless codons, or degrade genetic information.
One possible objection: point mutuations often lead to non-functional proteins, thus indicating a loss of information.
Counter: But information is not actually lost or degraded. Each codon still has meaning, and the sentence as a whole has meaning- it still produces a protein, if a non-functional one. This is where the analogy really breaks down. The language of DNA is not simply information, it has a physical significance- it produces proteins.
DNA can only be viewed as a set of instructions for making proteins rather than any old smalltalk, though even here the analogy breaks down. DNA doesn't tell something else how to build a protein, it is directly involved in the building process. If only the instructions to my new ikea table set did that!
Additionally, the instructions have not lost meaning when a point mutation produces a non-functional protein. The instructions are just as clear as before, "build this list of amino acids in a chain." The language is still just as readable. The instructions just simply don't work.
Point mutations in the English language produce nonsensical words. Point mutations in the genetic language never produce nonsensical words, they always produce a changed but still meaningful phrase. Thus, treating DNA as a language like English is silly.
Edited by platypus, : No reason given.