PreDarwinian evolution, prebiotic change: a principle of least selection

Abstract

AbstractEvolution prior to its Darwinian era occurred in an age of variation. Events allowed by starting materials, chemistry and physics were realized, directed by intrinsic probabilities. In this landscape, a principle of least selection defines the most probable evolutionary path. For selection from a population where x varies, the rate of x evolution dx/dt = αΔμ. μ is the population mean of the selected property x, α a proportionality constant. Explicit equations for selected change Δμ are presented. Simple results exist for common cases; for example, selecting for x ≥ a threshold. Maximizing Δμ minimizes need for selection. Least selections for x demand maximal dependence on x, maximal x standard deviation σ, and maximal lower x threshold (consistent with the need for a survivor). Least selection is free of the cost of natural selection, thus can support rapid evolution. Least selection also unites previous seemingly independent optima. As examples, evolution via ‘starting bloc selection’ and ‘chance utility’ (where selection spans a minimal change) and ‘near-ideal reactions’ (where variable reactant supplies recurrently create easy reactions) occur via transitory paths of least selection. ‘Bayesian convergence’ is guaranteed by least selection’s extremum (which sharply defines evolution’s path). ‘Distribution fitness’ (specific outcomes selected among multiple concurrent variations) is least selection of rare functional minorities. Inheritance of encoded chemical capabilities first evolves because templating and catalysis are related, potentially joined in a single molecular complex. Least selection defines directions, biostructures define destinations for likely pathways of preDarwinian evolution.