“By changing the strength of synaptic connections, animals learn.1 Learning confers a huge evolutionary advantage, because the animal can adapt to a range of circumstances. Learning also speeds up the rate of evolution itself. Initially, neurons were organized into nerve nets, which are distributed throughout the organism and serve to coordinate activities such as eating and digestion or the timed contraction of muscle cells across a wide area. The graceful propulsion of jellyfish is the result of a nerve net. Jellyfish have no brains at all.”