A tightly controlled cell cycle is considered a defining feature of eukaryotes and is marked by discrete rounds of DNA replication and cell division. Progress through the cycle is controlled by enzymes whose activity oscillate due to coordinated waves of expression (production) and degradation (break down and recycling). In searching for shared regulatory principles of the archaeal and eukaryotic cell cycle, we discovered that an archaeon uses degradation, mediated by evolutionarily conserved machinery, to control their cell cycle – just as eukaryotes do. Taken together, this finding supports the idea that eukaryotic cell cycle control traces back to archaea.