The Only Constant of Life's Origin Is Change: The Importance of Chemical Fluxes in Prebiotic Environments

High concentrations have long been thought to be important in prebiotic chemistry as they offer a way to circumvent a lack of available enzymatic catalysis to overcome kinetic barriers. Here, we argue that fluxes and timescales are also of critical importance. Fluxes and timescales determine, in part, whether an environment can achieve high concentrations of reactants and, in particular, place a critical constraint on whether high concentrations of product molecules can be maintained. We focus on closed basin lakes, which offer a viable way to concentrate molecules relative to background sources under benign conditions. From the perspective of P, HCN and its derivatives, and S, these systems may yield competitively high concentrations of reactants. Nonetheless, closed basin lakes often have limited fluxes of reactants, which places tight constraints on the concentrations of product molecules that can be maintained at steady state. In conjunction with experimentally measured reaction kinetics, an opportunity exists to discriminate between the plausibility of environments on the basis of their simulated ability to generate desired concentrations of products over relevant timescales. Crucially, to make such an evaluation is extremely difficult to do with confidence without quantitatively dealing with fluxes and timescales. Therefore, future work should routinely and systematically consider these aspects alongside molecule concentrations in environmental systems of interest and in experiments.