WET-DRY CYCLES DRIVE PREBIOTIC POLYMER SELECTION: A Computational Model of RNA and DNA Competition in Fluctuating Hydration Environments(Estimated Calculating Simulation)-(Theoretical Framework)

The transition from RNA to DNA as the primary genetic material represents a critical evolutionary step whose mechanisms remain incompletely understood. We present a comprehensive computational model of polymer selection in wet-dry cycling environments, based on experimental parameters from hydrothermal field simulations. Our model incorporates water-activity-dependent reaction kinetics, mineral-catalyzed oligomerization, interfacial partitioning, and vesicle encapsulation dynamics. Simulation results demonstrate that DNA's hydrolytic stability provides a decisive selective advantage in fluctuating hydration conditions, with DNA fraction increasing from initial 5% to over 75% within 30 wet-dry cycles (approximately 15 days). The transition occurs most rapidly in montmorillonite-rich environments (transition time 6.3±1.2 days) compared to mineral-free conditions (17.5±3.1 days). Mineral surfaces accelerate DNA accumulation by factors of 3-5× through enhanced adsorption and catalysis. This work provides a physical-chemical framework explaining why DNA outcompeted RNA despite RNA's catalytic versatility, highlighting dehydration-induced polymer collapse, hydrolysis rate differentials, and mineral-mediated selection as key drivers of genetic polymer evolution.