Emergence of Animals from Heat Engines. Part 1. Before the Snowball Earths

TL;DR

This paper proposes a novel heat engine-based model for the emergence of animals, focusing on thermal cycling mechanisms involving proteins and flagellar evolution, linking early biological processes to complex cellular structures.

Contribution

It introduces a new hypothesis connecting thermal gradients and protein oscillations to the evolution of animal motility structures and cellular control systems.

Findings

Thermal cycling via thermotethers could have driven early biological energy conversion.

Evolution of flagellar motors involved thermosynthesis and proton-pumping mechanisms.

Proposes a link between bacterial flagella and eukaryotic cellular control centers.

Abstract

Previous studies modelled the origin of life and the emergence of photosynthesis on the early Earth-i.e. the origin of plants-in terms of biological heat engines that worked on thermal cycling caused by suspension in convecting water. In this new series of studies, heat engines using a more complex mechanism for thermal cycling are invoked to explain the origin of animals as well. Biological exploitation of the thermal gradient above a submarine hydrothermal vent is hypothesized, where a relaxation oscillation in the length of a protein 'thermotether' would have yielded the thermal cycling required for thermosynthesis. Such a thermal transition driven movement is not impeded by the low Reynolds number of a small scale. In the model the thermotether together with the protein export apparatus evolved into a 'flagellar proton pump' that turned into today's bacterial flagellar motor after the acquisition of the proton-pumping respiratory chain. The flagellar pump resembles Feynman's ratchet, and the 'flagellar computer' that implements chemotaxis a Turing machine: the stator would have functioned as Turing's paper tape and the stator's proton-transferring subunits with their variable conformation as the symbols on the tape. The existence of a cellular control centre in the cilium of the eukaryotic cell is proposed that would have evolved from the prokaryotic flagellar computer.