A Dissipative Photochemical Origin of Life: The UVC Abiogenisis of Adenine

TL;DR

This paper explores how non-equilibrium thermodynamics and photochemical processes driven by UVC light could have led to the formation of life’s fundamental molecules, exemplified by adenine, on the early Earth.

Contribution

It introduces a thermodynamic and photochemical model for the abiogenesis of adenine from simple precursors under UVC radiation, emphasizing dissipative structuring and proliferation mechanisms.

Findings

Adenine can form from HCN and H2O under UVC light within vesicles.

Photochemical reactions exhibit multiple stationary states with increasing dissipative efficacy.

Environmental conditions influence the kinetic pathways and efficiency of adenine synthesis.

Abstract

I describe the non-equilibrium thermodynamics and the photochemical mechanisms which may have been involved in the dissipative structuring, proliferation and evolution of the fundamental molecules at the origin of life from simpler and more common precursor molecules under the impressed UVC photon flux of the Archean. Dissipative structuring of the fundamental molecules is evidenced by their strong and broad wavelength absorption bands and rapid radiationless dexcitation in this wavelength region. Proliferation arises from the auto- and cross-catalytic nature of the intermediate products. Evolution towards states of concentration profiles of generally increasing photon disspative efficacy arises since the system has numerous stationary states, due to the non-linearity of the photochemical and chemical reactions with diffusion, which can be reached by amplification of a molecular concentration fluctuation near a bifurcation. An example is given of photochemical dissipative abiogenisis of adenine from the precursors HCN and H$_2$O within a fatty acid vesicle on a hot ocean surface, driven far from equilibrium by the impressed UVC light. The kinetic equations are resolved under different environmental conditions and the results analyzed within the framework of Classical Irreversible Thermodynamic theory.