Abstract
How can living matter arise from dead matter? All known living systems are built around information stored in RNA and DNA. To protect this information against molecular degradation and diffusion, the second law of thermodynamics imposes the need for a non-equilibrium driving force. Following a series of successful experiments using thermal gradients, we have shown that heat gradients across sub-millimetre pores can drive accumulation, replication, and selection of ever longer molecules, implementing all the necessary parts for Darwinian evolution. For these lab experiments to proceed with ample speed, however, the temperature gradients have to be quite steep, reaching up to 30 K per 100 μm. Here we use computer simulations based on experimental data to show that 2000-fold shallower temperature gradients - down to 100 K over one metre - can still drive the accumulation of protobiomolecules. This finding opens the door for various environments to potentially host the origins of life: volcanic, water-vapour, or hydrothermal settings. Following the trajectories of single molecules in simulation, we also find that they are subjected to frequent temperature oscillations inside these pores, facilitating e.g. template-directed replication mechanisms. The tilting of the pore configuration is the central strategy to achieve replication in a shallow temperature gradient. Our results suggest that shallow thermal gradients across porous rocks could have facilitated the formation of evolutionary machines, significantly increasing the number of potential sites for the origin of life on young rocky planets.
Highlights
The formation of RNA-like biopolymers that exhibit both catalytic functions and information storage capabilities is central to the origin of life
The problem can be approached by searching for geological nonequilibrium conditions that make an origin of life possible, if not highly likely or even imperative under certain boundary conditions. Such a search will focus on experimentally testable conditions that create an evolutionary machine for protobiomolecules, achieving the first steps of Darwinian evolution naturally by a combination of physico-chemical effects
Porous rocks comprise multiple branched pore systems which serve as water channels
Summary
The formation of RNA-like biopolymers that exhibit both catalytic functions and information storage capabilities is central to the origin of life. These surface-based microhabitats provide wet–dry cycles and UV illumination for trapped molecules, facilitating the generation and polymerization of nucleotides.[9] (d) Numerical approaches show that elongated pore systems within shallow temperature gradients efficiently accumulate molecules such as DNA and RNA (1) and enable a heat-driven replication reaction due to cyclic temperature changes induced by the laminar thermal convection (2).
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