The Expense of Neuro-Morpho Functional Machines

The impact of the environment on the evolution of increasingly complex morphologies (bodies) and controllers (brains) remains an open question in evolutionary biology and has important implications for the evolutionary design of robots that must function across a range of environments. This study evaluates the relationship between between task difficulty (environment complexity) and evolved morphological and neural complexity given complexity costs in the form of body and brain energy requirements. We evolve body-brain couplings for increasingly difficult cooperative transport tasks in a collective robotic gathering simulation. The impact of imposing costs on morphological and controller complexity during robot body-brain evolution is evaluated across increasingly complex environments. Results indicate that imposing morphological and neural (energy) costs on complexity induces the evolution of robots using simpler controllers and morphologies but with negligible behavior (task performance) differences in simple environments. However, increased neural and morphological complexity was beneficial as environment complexity increased.