Two Metres of Instructions
Biology · · 6 min read · By No Design Editorial
Chemistry permits the order of the letters in DNA. It does not dictate it. That gap is the whole argument, and it is not a gap in our knowledge.
The human genome runs past three billion letters. Read them aloud at one per second, without pause, and you would not finish for about ninety-five years. Stretched out, the DNA in a single cell would reach about two metres, and it folds into a nucleus a few thousandths of a millimetre across while staying readable, copyable and repairable.
The packing is impressive. The argument is elsewhere, and it is easy to miss.
The bond joining each base to the sugar-phosphate backbone has effectively the same energy regardless of which base it is. Chemistry is indifferent to the order. That indifference is not a gap in our knowledge waiting to be filled in; it is the reason DNA can carry information at all. A medium that chemistry forced into one arrangement could not spell anything, in the same way that a magnet forcing iron filings into a fixed pattern cannot write a sentence. Michael Polanyi made this point in 1968 and it has not been answered since.
There is a second argument that usually gets run together with the first, and it is the less familiar one. DNA replication is proofread in a cascade: the polymerase selects correctly to about one error in a hundred thousand, proofreading catches most of what slips through, and mismatch repair catches most of the rest, ending near one error in ten billion.
Sit with what error correction requires. A system can only correct a mistake if there is a standard defining what counts as a mistake. Chemistry has no opinion about which base 'should' be there. Something has to specify the correct state before an error can be recognised as an error.
From Chapter 5: Signs in the Small.
Tags: DNA, Information, Error Correction, Quran