The identification of biological modules at the systems level often follows top-down decomposition of a task goal, or bottom-up decomposition of multidimensional data arrays into basic elements or patterns. This approach has been used to understand the neural control of locomotion in human adults, where a small set of basic patterned commands are directed to the leg muscles. However, the development of these modules and their interaction with the environment is still not well understood. Further research is needed to elucidate the evolutionary and developmental processes that shape the neural control of locomotion in humans.