A Tiny RNA That Copies Itself: What QT45 Solves, and What It Leaves Open

Cambridge chemists found a 45-letter RNA that can copy its own complementary strand. It is a genuine advance in the chemistry of replication. Whether it explains the origin of biological information is a separate question, and the authors do not claim it does.

Published in Science, February 12, 2026. Summarized August 25, 2026.

What did the researchers make?

A team at the MRC Laboratory of Molecular Biology in Cambridge screened random pools of RNA and isolated QT45, a polymerase ribozyme just 45 nucleotides long. In a slush of partly frozen water and salts, QT45 can stitch together short triplet building blocks to copy an RNA template, including copying its own complementary strand, at 94.1 percent per-letter accuracy. The headline is that a catalytic RNA with copying function can be far smaller and simpler than anyone had shown before.

Is this a self-replicating molecule?

Not yet, and the team says so plainly. QT45 can copy its complement in one test tube and assemble a version of itself in another, but the two reactions have not been combined in a single pot, so the replication cycle is not closed. Their stated next goal is to run both steps together and close that loop.

How fast and how efficient is it?

Slow, and inefficient. The full-length product forms at a yield of roughly 0.2 percent over 72 days. One chemist commenting on the work called that rate "unbelievably slow," and the authors agree the yield would need to improve dramatically before such a system could sustain itself, grow, and evolve.

So does this show life could start on its own?

It shows that a short RNA can chemically catalyze the copying of a sequence. It does not show where a functional, information-bearing sequence would come from in the first place. QT45 was located by directed screening and selection in a lab, not produced by unguided chemistry on a lifeless Earth.