Starting at early evolution develops the hypothetical species Magna superstes which evolved a genetic circuit for controlling reproduction based on the environment. When times are tough gene A is expressed and the cells do not reproduce. When times are better gene B is expressed which suppresses/silences gene A and the cells reproduce. Gene B has a secondary function wherein it repairs DNA. When the DNA is damaged it begins to repair it, gene A is expressed and reproduction is stopped. This combination of reproduction control in response to environment and DNA repair (fidelity) enabled this early cellular organism to survive. While the organism is hypothetical, the control circuit is shared across all species.