Controlling development and chemotaxis of soft-bodied multicellular animats with the same gene regulatory network

The ability to actively forage for resources is one of the defining properties of animals, and can be seen as a form of minimal cognition. In this paper we model soft-bodied robots, or “animats”, which are able to swim in a simulated twodimensional fluid environment toward food particles emitting a diffusive chemical signal. Both the multicellular development and behaviour of the animats are controlled by a gene regulatory network (GRN), which is encoded in a linear genome. Coupled with the simulated physics, the activity of the GRN affects cell divisions and cell movements during development, as well as the expansion and contraction of filaments connecting the cells in the swimming adult body. The global motion that emerges from the dynamics of the animat relies on the spring-like filaments and drag forces created by the fluid. Our study shows that it is possible to evolve the animat’s genome (through mutations, duplications and deletions) to achieve directional motion in this environment. It also suggests that a “minimally cognitive” behaviour of this kind can emerge without a central control or nervous system.