A colorful origin for the genetic code: Information theory, statistical mechanics and the emergence of molecular codes

TL;DR

This paper explores the origin of the genetic code through an information-theoretic lens, modeling it as an evolving, error-prone communication channel influenced by evolutionary pressures and phase transition phenomena.

Contribution

It introduces a novel model using rate-distortion theory to explain the emergence of the genetic code as a phase transition driven by conflicting evolutionary forces.

Findings

The genetic code's emergence is linked to a second-order phase transition.

The model identifies the code's fitness based on information channel properties.

Topology of the error-graph influences the code's structure and evolution.

Abstract

The genetic code maps the sixty-four nucleotide triplets (codons) to twenty amino-acids. While the biochemical details of this code were unraveled long ago, its origin is still obscure. We review information-theoretic approaches to the problem of the code's origin and discuss the results of a recent work that treats the code in terms of an evolving, error-prone information channel. Our model - which utilizes the rate-distortion theory of noisy communication channels - suggests that the genetic code originated as a result of the interplay of the three conflicting evolutionary forces: the needs for diverse amino-acids, for error-tolerance and for minimal cost of resources. The description of the code as an information channel allows us to mathematically identify the fitness of the code and locate its emergence at a second-order phase transition when the mapping of codons to amino-acids becomes nonrandom. The noise in the channel brings about an error-graph, in which edges connect codons that are likely to be confused. The emergence of the code is governed by the topology of the error-graph, which determines the lowest modes of the graph-Laplacian and is related to the map coloring problem.