LOL. @Eddie dreams he is more an authority than say, Tom Cech:
There are two RNA worlds. The first is the primordial RNA world, a hypothetical era when RNA served as both information and function, both genotype and phenotype. The second RNA world is that of today’s biological systems, where RNA plays active roles in catalyzing biochemical reactions, in translating mRNA into proteins, in regulating gene expression, and in the constant battle between infectious agents trying to subvert host defense systems and host cells protecting themselves from infection. This second RNA world is not at all hypothetical, and although we do not have all the answers about how it works, we have the tools to continue our interrogation of this world and refine our understanding. The fun comes when we try to use our secure knowledge of the modern RNA world to infer what the primordial RNA world might have looked like.
My usage of the term is well, well within its normal meaning.
I’m sure @Eddie can find, in his library, the following:
The term “RNA world” was first coined by Gilbert (1986), who was mainly interested in how catalytic RNA might have given rise to the exon–intron structure of genes. But the concept of RNA as a primordial molecule is older, hypothesized by Crick (1968), Orgel (1968), and Woese (1967). Noller subsequently provided evidence that ribosomal RNA is more important than ribosomal proteins for the function of the ribosome, giving experimental support to these earlier speculations (Noller and Chaires 1972; Noller 1993). The discovery of RNA catalysis (Kruger et al. 1982; Guerrier-Takada et al. 1983) provided a much firmer basis for the plausibility of an RNA world, and speculation was rekindled. The ability to find a broad range of RNA catalysts by selection of RNAs from large random-sequence libraries (SELEX) (Ellington and Szostak 1990; Tuerk and Gold 1990; Wright and Joyce 1997) fueled the enthusiasm, and made it possible to conceive of a ribo-organism that carried out complex metabolism (Benner et al. 1989). The widely accepted order of events for the evolution of an RNA world and from the RNA world to contemporary biology is summarized in Figure 1.
Did an RNA world exist? Some of the most persuasive arguments in favor of an RNA world are as follows. First, RNA is both an informational molecule and a biocatalyst—both genotype and phenotype—whereas protein has extremely limited ability to transmit information (as with prions). Thus, RNA should be capable of replicating itself, and indeed RNA can perform the sort of chemistry required for RNA replication (Cech 1986). Second, it is more parsimonious to conceive of a single type of molecule replicating itself than to posit that two different molecules (such as a nucleic acid and a protein capable of replicating that nucleic acid) were synthesized by random chemical reactions in the same place at the same time. Third, the ribosome uses RNA catalysis to perform the key activity of protein synthesis in all extant organisms, so it must have done so in the Last Universal Common Ancestor (LUCA). Fourth, other catalytic activities of RNA—activities that RNA would need in an RNA world but that have not been found in contemporary RNAs—are generally already present in large combinatorial libraries of RNA sequences and can be discovered by SELEX. Fifth, RNA clearly preceded DNA, because multiple enzymes are dedicated to the biosynthesis of the ribonucleotide precursors of RNA, whereas deoxyribonucleotide biosynthesis is derivative of ribonucleotide synthesis, requiring only two additional enzymatic activities (thymidylate synthase and ribonucleotide reductase.) Finally, a primordial RNA world has the attractive feature of continuity; it could evolve into contemporary biology by the sort of events that are well precedented, whereas it is unclear how a self-replicating system based on completely unrelated chemistry could have been supplanted by RNA.
Opinions vary, however, as to whether RNA comprised the first autonomous self-replicating system or was a derivative of an earlier system. Benner et al. (2010) and Robertson and Joyce (2010) are circumspect, noting that the complexity and the chiral purity of modern RNA create challenges for thinking about it arising de novo. On the other hand, the recent finding that activated pyrimidine ribonucleotides can be synthesized under plausible prebiotic conditions (Powner et al. 2009) means that it is premature to dismiss the RNA-first scenarios. Yarus (2010), an unabashed enthusiast for an RNA world, argues for a closely related replicative precursor. In vitro evolution studies directed towards an RNA replicase ribozyme continue apace and are of great importance in establishing the biochemical plausibility of RNA-catalyzed RNA replication (Johnston et al. 2001; Zaher and Unrau 2007; Lincoln and Joyce 2009; Shechner et al. 2009).
What might the first ribo-organism have looked like? Schrum et al. (2010) describe progress in achieving replication of simple nucleic acid-like polymers within lipid envelopes, thereby constituting “protocells.” These liposomes can grow and upon agitation can divide to give daughter protocells, carrying newly replicated nucleic acids. Whether by lipids or other means, some form of encapsulation must have been a key early step in life. Encapsulation can protect the genome from degradation and predation, allows useful small molecules to be concentrated for the cell’s use, and enables natural selection by ensuring that the benefit of newly derived functions accrues to the organism that stumbled across them.
The question remains - how can Tour be praised for dismissing this, and much, much more?