Is pre-Darwinian evolution plausible?

BACKGROUND: This essay highlights critical aspects of the plausibility of pre-Darwinian evolution. It is based on a critical review of some better-known open, far-from-equilibrium system-based scenarios supposed to explain processes that took place before Darwinian evolution had emerged and that resulted in the origin of the first systems capable of Darwinian evolution. The researchers’ responses to eight crucial questions are reviewed. The majority of the researchers claim that there would have been an evolutionary continuity between chemistry and “biology”. A key question is how did this evolution begin before Darwinian evolution had begun? In other words the question is whether pre-Darwinian evolution is plausible. RESULTS: Strengths and weaknesses of the reviewed scenarios are presented. They are distinguished between metabolism-first, replicator-first and combined metabolism-replicator models. The metabolism-first scenarios show major issues, the worst concerns heredity and chirality. Although the replicator-first scenarios answer the heredity question they have their own problems, notably chirality. Among the reviewed combined metabolism-replicator models, one shows the fewest issues. In particular, it seems to answer the chiral question, and eventually implies Darwinian evolution from the very beginning. Its main hypothesis needs to be validated with experimental data. CONCLUSION: From this critical review it is that the concept of “pre-Darwinian evolution” appears questionable, in particular because it is unlikely if not impossible that any evolution in complexity over time may work without multiplication and heritability allowing the emergence of genetically and ecologically diverse lineages on which natural selection may operate. Only Darwinian evolution could have led to such an evolution. Thus, Pre-Darwinian evolution is not plausible according to the author. Surely, the answer to the question posed in the title is a prerequisite to the understanding of the origin of Darwinian evolution. REVIEWERS: This article was reviewed by Purificacion Lopez-Garcia, Anthony Poole, Doron Lancet, and Thomas Dandekar.