, RNA oligomers and peptides may have helped each other to evolve towards functional molecules by forming aptamer/metabolite binding complexes ( Figure 1 ). It is also important to note that a completely different perspective on the origins of life holds that energy transduction or metabolism had to precede the synthesis of a molecule as complex as RNA. The hypothesis of co-emergence and co-evolution of RNA and peptides provides a bridge between the RNA-first and metabolism-first perspectives. Figure 1. Open in a new tab In vesiculo chemical evolution of RNA- and protein-like molecules towards an RNA-peptide world. In this scenario, RNAs, peptides and lipids might have co-emerged and co-evolved in a synergistic and mutualistic manner. In this review, the major focus is on the emergence of the first RNA oligomers. An introductory section to define the main steps of non-enzymatic RNA polymerization and the RNA world hypothesis are described. The methods used for synthesizing activated nucleotides, essential for non-enzymatic RNA polymerization, are summarized. Major advances in non-enzymatic RNA oligomerization and some of their limitations are then presented. Finally, we outline a new model based on a multi-component prebiotic soup. 2. Non-Enzymatic RNA Polymerization The process of non-enzymatic polymerization of RNA, as generally accepted in the literature, can be divided into three smaller steps, namely (1) the emergence of the first RNA oligomers, which would have provided the basis for (2) template-directed RNA polymerization, resulting optimistically in robust and functional RNA polymers capable of self-ligation and self-catalysis, finally leading to (3) a non-enzymatic RNA replication ( Figure 2 ). In the present review, the focus was on work in which the first step was studied (1). The term “oligomerization” was used to designate this step, which corresponds to a condensation of RNA monomers in the absence of a template. For template-directed RNA polymerizati