In their landmark 1961 paper on the lac operon, Nobel laureates François Jacob and Jacques Monod speculated that RNA might control gene activity in bacteria through base-pairing interactions. But once protein transcription factors were discovered, the idea was tossed aside. Sixty years later, a multi-institutional team of biologists shows that Jacob and Monod were on to something. Some species of bacteria, reports the team in Nature, have evolved an RNA-guided gene activating system by transforming a copy of a CRISPR-Cas gene-cutting system.