The ribotype theory

The first model of postchemical evolution was proposed in 1981 with the ribotype theory on the origin of life, and with the concept of ribotype, a term that indicates all RNAs and ribonucleoproteins of any organic system (Barbieri, 1981). Since ribonucleoproteins are advanced compounds, however, the name ribosoids was introduced to indicate all molecules made of RNA, or RNA and peptides, and the ribotype was also defined as the collective of all ribosoids of an organic system.
The reconstruction of the ribotype theory starts with the first organic systems that were capable of producing RNAs, be they Fox’s microspheres, Wächtershäuser’s vescicles or Dyson’s minicells, and is compatible therefore with almost all metabolism-first models of chemical evolution. More precisely, it is compatible with all scenarios where primitive metabolic systems could grow, divide by budding or fission, and diversify with a generalized drift mechanism of the type described by Kimura and by Dyson.
After this first phase of chemical evolution, the rest of precellular evolution took place, according to the ribotype theory, in a world of ribosoids, that is to say in a RNP world. The difference between RNA world and RNP world, may seem small, at first sight, but in reality is enormous, because the RNA world implies a replication-first paradigm while the RNP world belongs to a metabolism-first framework. The ribotype theory was proposed before the discovery of ribozymes, but was also based on the idea that some RNAs can behave as enzymes. More precisely, the idea was that some primitive RNAs were similar to fragments of ribosomal RNAs, and could catalyze a peptide bond between any two amino acids. They were, in other words, polymerizing ribosoids.
The idea that the active players of protein synthesis are ribosomal RNAs, and not proteins, was proposed in 1970 by Carl Woese, and in those days it was only a speculation, but in 1988 Nitta, Ueda and Watanabe demonstrated that a ribosomal RNA fragment, totally deprived of proteins, is still capable of forming peptide bonds.