The history of studies on the taxonomy and evolutionary biology of the three-spined stickleback Gasterosteus aculeatus from the 18th century to the present is reviewed. After the publication of Darwin's Origin of the Species, four important dates, 1925, 1947, 1967 and 2001, are identified as marking major gains in the understanding of the evolution of the diversity in morphological, life-history, physiological and behavioural traits that characterizes G. aculeatus. The period 1925–1970 led to the identification of the main themes of research: status and adaptive significance of lateral-plate morphs; inter and intrapopulation trait variation in freshwater resident G. aculeatus and the adaptive significance of the variation. Between 1970 and 2001, these themes were investigated using variation observed particularly along the Pacific coast of the U.S.A. and Canada, notably in the Cook Inlet region of Alaska and the Haida Gwaii Archipelago. Studies on adaptive radiation and reproductive isolation in lacustrine, ecomorph pairs (limnetics and benthics) discovered in the Strait of Georgia region have been particularly productive. From 2001, the application of genomic studies to these problems began to open up the study of the relationships between genotype, phenotype and selective advantage to causal analysis.