Researchers Unveil a Simple Mechanism for RNA Replication on Early Earth
Chemists from University College London (UCL) and the MRC Laboratory of Molecular Biology have made a significant breakthrough in understanding how RNA (ribonucleic acid) may have self-replicated on the early Earth—a process considered vital to the origin of life.
Scientists have long hypothesized that RNA served as the first carrier and copier of genetic information in primitive life, before the evolution of DNA and proteins. However, replicating RNA under plausible prebiotic conditions has remained a major scientific hurdle. RNA strands naturally pair into double helices, similar to DNA, making them difficult to separate and replicate without modern enzymes.
The research team, in a study published in Nature Chemistry, found that using “trinucleotide” RNA building blocks—groups of three nucleotides—helped overcome this obstacle. They mixed these triplets in water and subjected the solution to cycles of heat and acid, which caused the RNA strands to separate. Freezing the solution then created small pockets of liquid between ice crystals, where the triplets attached to the single strands and prevented them from re-binding. This environment enabled RNA replication to take place.
By repeating this cycle of heating, acid exposure, freezing, and thawing—conditions that could have naturally occurred in early Earth’s environments, such as in geothermal regions or day-night temperature shifts—the researchers observed RNA strands growing long enough to perform biological roles.
Dr. Philipp Holliger, the project lead from the MRC Laboratory of Molecular Biology, explained, “The leap from chemistry to biology lies in the storage and copying of molecular information. Replication is the mechanism that enables information to be passed from one generation to the next.”
Lead author Dr. James Attwater (UCL and MRC LMB) added, “Replication is the foundation of all biology. Yet we have no direct evidence of what the very first replicator looked like. Even the simplest ancestral organism, LUCA, was already very complex. It’s likely that RNA molecules once managed these replication processes before proteins and DNA came into play.”
He also noted that the triplet building blocks used in this study don’t exist in modern biology, but likely represent simpler molecular forms from an earlier stage of evolution. These structures appear more suited to replication under primitive Earth-like conditions.
The research also showed that RNA replication is unlikely in salty conditions, such as seawater, because salt disrupts freezing and prevents sufficient concentration of RNA building blocks. Likewise, while evaporation in hot climates can concentrate RNA, elevated temperatures make RNA molecules unstable and prone to degradation.
The origin of life likely involved more than just RNA. Scientists believe that a combination of molecules—RNA, short amino acid chains (peptides), protective lipid membranes, and early enzymes—contributed to the emergence of life. Ongoing research at both UCL and MRC LMB is piecing together how key biological molecules, including nucleotides, amino acids, and lipids, could have formed from simple chemicals found on the early Earth.
This latest discovery was funded by the Medical Research Council (MRC), a part of UK Research and Innovation (UKRI), along with support from the Royal Society and the Volkswagen Foundation.
