Evolution can be viewed as a dynamic process that leads to increased complexity. This process appears to be driven by the interplay between a breaking of symmetry in biological organisms that leads to increased differentiation and complexity on one hand, and the intrinsic tendency of physical systems to maintain symmetry on the other. Thus thermal ratchets act to break symmetry, suggesting they may have played an important role is the evolution of complexity, while physical systems, including biological ones, have a tendency to maintain symmetry. We propose that, in the brain, development is driven by a combination of asymmetry-creating properties of cytoskeletal thermal ratchets and by the symmetry-maintaining properties of cytoskeletal tensegrity architecture.