Fig. 1: Natural and synthetic multicellularity.

These case studies include three natural examples (left column) of patterns and processes associated with hierarchical and emergent mechanisms and evolutionary dynamics. A classic example of a top-down mechanism in morphogenesis is the formation of gradients and stripes in Drosophila (a Data from the FlyEx database). These processes can be approached by (b) a synthetic band-pass filter using engineered E. coli¹³⁸ (image courtesy of Ron Weiss), (c) the generation of multiple coexisting cell fates⁷³ (image courtesy of Michael Elowitz) and (d) programmable symmetry breaking-induced structure formation (from ref. ⁷⁸, image courtesy of Wendell Lim). Morphogenetic processes are spatially organized through multiscale feedback loops shaping embryos (e; image courtesy of James Sharpe). Synthetic counterparts of the underlying emergent phenomena include (f) kidney organoid development, (g) Turing-like branching morphogenesis of bacteria (g, h) the development of Anthrobots. The simplest, aneural metazoans are exemplified by Placozoans (image courtesy of Sebastian R. Najle, CRG) (i), while evolved cell assemblies emerge under synthetic selection mechanisms, including cell-cell adhesion to escape from predators (j; adapted from ref. ¹². with permission), yeast MC aggregates (k; adapted from ref. ¹⁵⁶, with permission) and Xenobots (l). The latter were obtained through a combination of in silico evolutionary algorithms and bioengineering.