Genomes: at the edge of chaos with maximum information capacity

TL;DR

This paper introduces an order index, phi, to measure how close genomes are to the edge of chaos, revealing that most genomes are in a narrow range near this critical point, driven by neutral evolution.

Contribution

It proposes a new quantitative measure, phi, for assessing genomic order and demonstrates its effectiveness across diverse genomes.

Findings

Genomes have phi values narrowly clustered around 0.037.

Genomes are positioned at the edge of chaos, halfway between order and randomness.

Neutral evolution dynamics drive genomes toward this fixed-point.

Abstract

We propose an order index, phi, which quantifies the notion of ``life at the edge of chaos'' when applied to genome sequences. It maps genomes to a number from 0 (random and of infinite length) to 1 (fully ordered) and applies regardless of sequence length. The 786 complete genomic sequences in GenBank were found to have phi values in a very narrow range, 0.037+/-0.027. We show this implies that genomes are halfway towards being completely random, namely, at the edge of chaos. We argue that this narrow range represents the neighborhood of a fixed-point in the space of sequences, and genomes are driven there by the dynamics of a robust, predominantly neutral evolution process.