Persistent increase in non-food set mass due to novel viable loops. We simulated 460 runs lasting 30,000 growth steps each, with food set size M = 4, P' = 0.75, P'' = 0.0025, K = 0 (without inhibition), but with spontaneous emergence of rare novel species from uncatalyzed reactions. 5 out of 460 runs showed persistent increases in non-food set mass (B). This was always due to the incorporation of at least one viable loop. (A) Example of viable loop organization used in evolutionary simulations. Solid lines: reactions; dotted lines: catalytic activities. Orange dotted lines show the superimposed autocatalytic loop. The original network, on the left side of the blue line, is not shown in detail.