Simple model for the Darwinian transition in early evolution

TL;DR

This paper presents a minimal stochastic model illustrating how early life transitioned from collective horizontal gene transfer to individual vertical descent, leading to the emergence of the first species.

Contribution

It introduces a new minimal model demonstrating how stochastic switching and hypernetwork interactions can destabilize collective HGT and promote individuality in early evolution.

Findings

HGT-dominated dynamics can be intermittently destabilized by selection.

Stochastic switching can lead to the emergence of vertical descent.

The model supports a route from collective to individual evolution.

Abstract

It has been hypothesized that in the era just before the last universal common ancestor emerged, life on earth was fundamentally collective. Ancient life forms shared their genetic material freely through massive horizontal gene transfer (HGT). At a certain point, however, life made a transition to the modern era of individuality and vertical descent. Here we present a minimal model for this hypothesized "Darwinian transition." The model suggests that HGT-dominated dynamics may have been intermittently interrupted by selection-driven processes during which genotypes became fitter and decreased their inclination toward HGT. Stochastic switching in the population dynamics with three-point (hypernetwork) interactions may have destabilized the HGT-dominated collective state and led to the emergence of vertical descent and the first well-defined species in early evolution. A nonlinear analysis of a stochastic model dynamics covering key features of evolutionary processes (such as selection, mutation, drift and HGT) supports this view. Our findings thus suggest a viable route from early collective evolution to the start of individuality and vertical Darwinian evolution, enabling the emergence of the first species.