RNA World Hypothesis Remains Open Question as Scientists Weigh Life’s Origins
The RNA world idea holds that life started with RNA molecules that both stored genetic information and drove chemical reactions. Researchers explain the chicken-and-egg problem behind it, the ribozyme discoveries that backed it, and a 2019 lab experiment that exposed a weakness.
Did life begin in an RNA world? The hypothesis, which says the first life-like chemistry ran on RNA alone, is still an open question for science as of November 2026. It rests on a puzzle about how living cells copy their genetic information.
The chicken-and-egg problem
Life appeared on a barren Earth some 4 billion years ago. Many researchers think self-replication, the ability to store and copy genetic information reliably, is life's most core ability. If so, the earliest life-forms would have needed the kinds of molecules cells use for that job today.
In modern cells, DNA encodes the shapes of proteins. RNA carries that information so cells can build the proteins. Yet proteins are involved at every step: they duplicate DNA, transcribe DNA into RNA and help use RNA to make more proteins.
That creates a deadlock. Useful proteins cannot be made without DNA, but proteins are needed to make DNA in the first place.
How ribozymes changed the picture
A discovery in the late 1980s seemed to break the deadlock. Researchers found that some RNAs can act as catalysts, meaning they speed up chemical reactions. They named these RNAs ribozymes, after protein catalysts called enzymes.
Ribozymes suggested that RNA can carry sequence information and also do catalytic work, covering the jobs of both DNA and proteins. Physicist-turned-biologist Walter Gilbert championed the resulting picture: life began as an RNA world.
The proposed story runs like this. Individual nucleotides, the building blocks of RNA, joined at random into chains. One chain happened to have the right sequence to act as a ribozyme that helps other RNAs form, and possibly to copy itself.
In 1996, researchers created a ribozyme that could stitch individual nucleotides together to form RNA. That raised the prospect of RNA that could replicate.
Copying errors would creep in, so some copies would differ slightly from their parent. With such mutations, Darwinian evolution becomes possible, because natural selection would favor mutants that copy themselves faster.
These evolving molecular systems would not be alive themselves. But some RNAs could plausibly evolve to catalyze metabolic processes or make other complex biomolecules, opening a path toward the first living protocells.
Where the idea runs into trouble
The theory sounds good on paper, but it has problems. In 2019, RNA biologist Gerald Joyce of the Salk Institute and his colleagues tested a method for making new ribozymes in the lab.
They built synthetic ribozymes able to make other RNAs, then scrambled the sequences slightly to let them evolve artificially. They eventually found a ribozyme that could synthesize the RNA from which it had evolved. But the mutations introduced in each round of evolution tended to kill off the ribozymes' catalytic activity.
