Emergent primordial heritability in short random RNA pools

The emergence of heritable molecular information is a fundamental step in the origins of life. Prior to the evolution of defined self-reproducing RNAs in the RNA world hypothesis, mixtures of primordial oligonucleotides may have supported more rudimentary forms of information propagation at the population level. To explore this possibility, we investigated the long-term dynamics of fully random short RNA pools under serial transfer conditions. Across multiple populations undergoing iterative nonenzymatic recombination and ligation, overall sequence compositions changed dynamically; however, sequence and structural traits emerged and exhibited modest yet detectable persistence, indicative of a primordial form of heritability. These traits were largely associated with terminal RNA regions, which tend to be unstructured and accessible for subsequent templating reactions, consistent with the enrichment of complementary sequences. The role of complementarity in shaping sequence composition was further confirmed using designed RNAs. Together, these results suggest that fully random RNA mixtures can exhibit a measurable, albeit weak, capacity to propagate newly generated information in the absence of enzymes, potentially representing an early step toward the emergence of genetic systems.