Is DNA analogous to human language?

"It all starts with random mutation, from which natural selection can choose winners. Since DNA is a language based on a four-letter alphabet (A, C, T, G); since letters form words (Codons) and words form instructions (Genes) we can test the concept in Plain English."
Mr Perry Marshall


This post forms part of a series on Mr Marshall's Random Mutator. You can find all the posts here:
  1. The Random Mutator of Perry Marshall.

  2. Is DNA Analogous to Human Language?

  3. How Random is Random Mutation in DNA?

  4. Does Darwinian Evolution Claim that DNA Mutations are Random?


The analogy that DNA is a language like Plain English is just a metaphor. It's a very convenient metaphor to explain the mechanisms of DNA, but as a metaphor, it should not be taken too literally. Operations on a string of text in English do not represent operations on DNA. Here is why:

DNA is a language based on a four letter alphabet (A, C, T, G)


This seems pretty valid and it does clarify the workings of DNA a little. However, letters in Plain English do not work like this:

"Each nucleotide sub-unit consists of a phosphate, deoxyribose sugar and one of the 4 nitrogenous nucleotide bases. The purine bases adenine (A) and guanine (G) are larger and consist of two aromatic rings. The pyrimidine bases cytosine (C) and thymine (T) are smaller and consist of only one aromatic ring.

In the double-helix configuration, two strands of DNA are joined to each other by hydrogen bonds in an arrangement known as base pairing. These bonds almost always form between an adenine base on one strand and a thymine on the other strand and between a cytosine base on one strand and a guanine base on the other."

[Transfer of information via the genetic code, Wikipedia]

The letters A, C, T and G represent nucleotides. While these letters are the basic building blocks of DNA, just like letters are the basic building blocks of words, nucleotides are further divisible into more basic building blocks.

Nucleotides from Wikipedia
A nucleotide is composed of a ring of nitrogen, carbon and oxygen atoms, a five carbon sugar (together referred to as a nucleoside) and one phosphate group.
[Nucleotide, Wikipedia]

While you could argue that letters are formed by ascenders, descenders, markers and serifs, these do not represent the basic building blocks of letters in the same way that a ring of nitrogen, carbon and oxygen atoms, a five carbon sugar and one phosphate group represent the basic building blocks of nucleotides.


The Gypsy Curse font from sinisterfonts.com. Does it look like nucleotides? Didn't think so.

Letters are not further divisible into functional parts in Plain English, but the nucleotides which make up DNA are further divisible into functional, stand-alone, chemical parts.

Furthermore, in any language there are rules which stipulate which letters can go next to which other letters. You'd mostly have a vowel next to a consonant, for instance.These rules are not determined by the message encoded in the text, but have to do with the conventions of the language.

This is different from DNA because DNA is not a language. DNA mostly forms as two strands: an adenine base on one strand and a thymine on the other strand and between a cytosine base on one strand and a guanine base on the other. This arrangement is not determined by convention, nor by the genetic code contained in the DNA, but the chemical properties of nucleotides and the resulting Hydrogen bonds.

Random mutations on a single string of Plain English text do not take the double helix structure of DNA into account.

This means the claim that we can test DNA concepts with Plain English is fundamentally flawed. The analogy that DNA is similar to Plain English is entirely inappropriate, as random operations on an entire string of text do not equate to any kind of operations on DNA at all.

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