Miniature Transport EngineersIn its vegetative phase, the slime moldPhysarum polycephalum“slimes” its way through the world seeking food. As it explores, it links previously found food sources with tubular structures.Teroet al.(p.439) report that if food sources are deposited on a plate in a pattern corresponding in miniature to the positions of the cities that surround Tokyo, the resulting network ofPhysarumtubules that develops is rather similar in structure to the railroad network that connects the Japanese cities. A model was produced that describes the adaptive network development displayed by the slime mold. This biologically inspired model might provide insight into how to implement properties like resistance of transport systems to local failures into similar human-designed systems.