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Selection (1859), Darwin paid special attention to difficulties with his theory, devoting an entire chapter to the subject. The evolution of electrogenesis was one such area of concern. He noted the difference in structure, innervation, and electrical power of different electric organs (EOs), and the absence of geological evidence for a possible common ancestor between the different taxa exhibiting EOs. He concluded that rather than being homologous structures, the EOs of different fishes should be considered analogous structures that evolved independently. He also raised questions about potential functions for weak EOs. Although electric emissions from weakly electric fish had not yet been discovered, Darwin believed that a functional, weak EO was a necessary step in the evolution of strong EOs. About a century later, the rigorous study of a fish that was found to produce weak electric fields provided answers to such …