First published 2 July 2012
Brainless Bodies: Controlling the Development and Behavior of Multicellular Animats by Gene Regulation and Diffusive Signals
M. Joachimczak, T. Kowaliw, R. Doursat, B. Wróbel
We present a model of parallel co-evolution of development and motion control in soft-bodied, multicellular animats without neural networks. Development is guided by an artificial gene regulatory network (GRN), with real-valued expression levels, contained in every cell. Embryos develop within a simulated physics environment and are converted into animat structures by connecting neighboring cells through elastic springs. Outer cells, which form the external envelope, are affected by drag forces in a fluid-like environment. Both the developmental program and locomotion controller are encoded into a single genomic sequence, which consists of regulatory regions and genes expressed into transcription factors and morphogens. We apply a genetic algorithm to evolve individuals able to swim in the simulated fluid, where the fitness depends on distance traveled during the evaluation phase. We obtain various emergent morphologies and types of locomotion, some of them showing the use of rudimentary appendages. An analysis of the selected evolved controllers is provided.