“…These universal RPApermissive design principles now represent a launching-point for future explorations of more complex phenotypes -including some classes of embryonic patterning problems, for instance, where integral control is known to play a role in promoting adaptation of segmentation boundaries to variations in organism size 14,15 . The identification of universal design principles for many other complex phenotypes, such as Turing patterns 37,40,41 and multistability/ switching-responses 42,43 , is likely to prove more challenging -due, in part, to the central role of equilibrium stabilities, or instabilities, in generating these responses. These grand challenges remain open, and we hope that our study will inspire bold new mathematical thinking in these vitally important directions.…”