Collective evolution and the genetic code

Abstract

A dynamical theory for the evolution of the genetic code is presented, which accounts for its universality and optimality. The central concept is that a variety of collective, but non-Darwinian, mechanisms likely to be present in early communal life generically lead to refinement and selection of innovation-sharing protocols, such as the genetic code. Our proposal is illustrated by using a simplified computer model and placed within the context of a sequence of transitions that early life may have made, before the emergence of vertical descent.

Fig. 1.

Communal evolution toward optimality of 80 codes with (blue) and without (red) HGT of coding regions. There is no barrier to HGT between different codes. The initial conditions are the same for both runs. Parameters: H = 0.4, φ = 0.99, μ = 10⁻⁴, ν = 0.01. (A) Time development of the average amino acid distance between neighboring codons, a proxy for code optimality. (B) Probability distribution histogram of code optimality for randomly generated codes. The horizontal axis is the frequency with which a given code optimality occurs; the vertical axis is the same as in A. (C) Time development of the average distance between codes.