Before DNA and proteins, life may have run entirely on RNA

RNA can both store genetic information, like DNA, and fold into shapes that catalyse reactions, like proteins, so several scientists in the late 1960s proposed early life ran on self-copying RNA alone, skipping DNA and protein. Woese, Crick and Orgel each floated versions of the idea around 1967-68, before anyone had found an RNA molecule behaving like an enzyme. The hypothesis gained traction in the 1980s, once biologists found RNA enzymes, called ribozymes, that do exactly that.

— Francis Crick, The Origin of the Genetic Code — Journal of Molecular Biology, 1968