Theory saying that earlyr forms of life may have relied solely on RNA to store genetic information and to catalyze chemical reactions. Proteins require DNA to store information, but DNA also requires protein to do biochemical work. Neither DNA nor protein can support life alone.
RNA is the only molecule that is capable of both self-replication and catalytic functioning. This concept was put forth in the 1960s by Carl Woese, Francis Crick and Leslie Orgel.