Life's molecular alphabet pre-ordained?

Linking to an interesting article describing a recently published paper.

Summary of the paper is as below -

Life uses 20 coded amino acids (CAAs) to construct proteins. This set was likely evolutionarily ‘standardized’ from smaller sets as organisms discovered how to make and encode them. Scientists modeled how the adaptive properties of the CAAs evolved over time. They found that sets containing even only a few CAAs were better than an enormous choice of alternatives, suggesting each time a modern CAA was discovered, it bootstrapped the set to include still more CAAs.

the interesting consequence to this idea is stated as below -

If true, the researchers speculate, it might mean that even given a large variety of starting points for developing coded amino acid sets, biology might end up converging on a similar set. As this model was based on the invariant physical and chemical properties of the amino acids themselves, this could mean that even Life beyond Earth might be very similar to modern Earth life.


Very interesting article @Ashwin_s. Thanks.

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On the flip side, scientists have had success in introducing non-canonical amino acids into bacteria:


The term “pre-ordained” is of course extremely loaded. I would have no issue with a statement that the amino acid alphabet used in life is expected to evolve convergently for it’s adaptive properties, but to say that this is “pre-ordained” goes further than the evidence can support.


Very fascinating. That does raise some questions concerning claims that the current genetic code is the best possible compromise code. I’m not sure this result really undermines that claim.