The free energy requirements of biological organisms; implications for evolution

TL;DR

This paper applies nonequilibrium thermodynamics to determine the minimal free energy organisms need for specific computations, linking thermodynamics with biological evolution and information processing limits.

Contribution

It extends thermodynamic analysis to biological organisms, deriving free energy requirements for stochastic input-output maps and their implications for evolution.

Findings

Derived minimal free energy for organisms' stochastic maps

Calculated optimal trade-offs between energy use and fitness

Discussed sunlight flux limits on biosphere information processing

Abstract

Recent advances in nonequilibrium statistical physics have provided unprecedented insight into the thermodynamics of dynamic processes. The author recently used these advances to extend Landauer's semi-formal reasoning concerning the thermodynamics of bit erasure, to derive the minimal free energy required to implement an arbitrary computation. Here, I extend this analysis, deriving the minimal free energy required by an organism to run a given (stochastic) map $\pi$ from its sensor inputs to its actuator outputs. I use this result to calculate the input-output map $\pi$ of an organism that optimally trades off the free energy needed to run $\pi$ with the phenotypic fitness that results from implementing $\pi$. I end with a general discussion of the limits imposed on the rate of the terrestrial biosphere's information processing by the flux of sunlight on the Earth.