A Tiny RNA That Copies Itself, and the Origin of Biological Information

Chemists at Cambridge found a 45-letter RNA that can copy its own complementary strand. It is a real step forward in the chemistry of replication, and it leaves the deeper question of where biological information comes from right where it was.

Published in Science on February 12, 2026.

What did the researchers make?

A team at the MRC Laboratory of Molecular Biology in Cambridge searched random pools of RNA and pulled out QT45, a copying enzyme just 45 nucleotides long. In a slush of half-frozen water and salts, it joins short building blocks to copy an RNA template, including its own mirror strand, with about 94 percent accuracy per letter. The headline is that a molecule with this ability can be far smaller than anyone had shown before.

Is it a self-replicating molecule?

Not yet. QT45 copies its mirror strand in one test tube and assembles a version of itself in another, but the two reactions have not been run together, so the loop of true self-replication is not closed. Closing it is the team's next goal.

How fast and efficient is it?

Very slow. The full-length copy forms at a yield of roughly 0.2 percent over 72 days. That rate would need to improve dramatically before such a system could sustain itself, grow, and evolve, and the researchers say as much.

Where did the working sequence come from?

From directed searching in the laboratory. The scientists screened large libraries and selected the rare sequences that happened to catalyze copying. The chemistry can reproduce a sequence once it exists. It does not account for how a functional, information-rich sequence arises in the first place.