Top-down Reconstruction of Processes and Early Evolutionary Stages without Specific Geochemical Considerations

Abstract

Abstract The vocabulary of origin-of-life researchers has been enriched recently by concepts and propositions such as “minimal cell, “chemoton,” and various “worlds.” The best known of the worlds is the “RNA-world.” Not less important is the “ancient genetic code.” One common denominator between these scientific propositions, which are rather different from one another, is that they represent early evolutionary stages in the origin-of-life processes, all of which preceede the progenote. A second common denominator between these propositions is that they are the results of back-extrapolations from extant biology to much earlier stages in the evolution of living entities, essentially without specific geochemical considerations. The distinction between topdown and bottom-up approaches is convenient but not always clear-cut; thus it is arbitrary to some extent.