The RNA World Hypothesis is a concept put forth in the 1960s by Carl Woese, Francis Crick and Leslie Orgel. It proposes that earlier life forms may have used RNA alone for the storage of genetic materialWalter Gilbert, a Harvard molecular biologist, was the first to use the term "RNA World" in an article published in 1986. The hypothesis posists that DNA later became the genetic material as a result of evolution because RNA was a relatively unstable molecule. According to the RNA World Hypothesis, around 4 billion years ago, RNA was the primary living substance, largely due to RNA’s ability to function as both genes and enzymes.

The main reasoning behind the hypothesis is that RNA is capable of self-replication and could therefore have carried genetic information across generations independently. This concept has been highly debated in the scientific world over the last 50 years.Experts now generally agree that non-living chemicals could not have given rise to bacterial cells in a single step and that intermediate, pre-cellular life forms must therefore have existed. Of the possible pre-cellular life models considered, the most popular is the RNA World.

In 1968, Sir Francis Crick proposed that RNA must have been the primary genetic material as it is capable of self-replication, owing to its ability to act as an enzyme. Moreover, RNA can also be converted to DNA by reverse transcription, which further strengthens the idea that the RNA world could have been the initial pathway to cells