Earth, a planetary PCR machine to create life, or the brief history of a tRNA

About 4 billion years ago, the Earth probably fulfilled the environmental conditions necessary to favour the transition from primitive chemistry to life. Based on a theoretical hairpin duplication origin of tRNAs and their putative peptide-coding capability before ribosomes existed, here I postulate that, at this hypothetical environment, Earth’s daily temperature cycles could have provided a unique planetary thermocycler to create self-replicating RNA hairpins that simultaneously templated amino acids polymerization in a primordial PCR well of prebiotic molecules. This early RNA hairpin-peptide interaction could have established a reciprocal nucleopeptide replicator that paved the way for catalytic translation and replication machineries towards the origin of LUCA.