- #1
Adeimantus
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I recently borrowed the book Information Theory, Evolution, and the Origin of Life by Hubert Yockey. In it he points to the fact that there can be no code from the amino acid alphabet (about 20 symbols) to the RNA/DNA alphabet (64 3-letter codons, a second extension of the 4-symbol alphabet {A,C,G,T}) and says this proves, beyond any doubt, that proteins were not the first step in the origin of life. No information can be transferred from proteins to DNA. However, he also says in the book that the genetic code probably evolved from an earlier code with 2-letter codons. This first extension of {A,C,G,T} has 16 symbols, which is less than 20. So doesn't that leave open the possibility of a code from the amino acid alphabet to the pre-DNA nucleic acid alphabet?