 Model organisms were often chosen for a particular field of study, but turned out to be invaluable for other fields as well. Drosophila is a case in point; Morgan was mainly interested in embryology when he chose Drosophila as a model system. This paid off enormously, but the fly was just as important for genetics itself, including evolutionary genetics (especially the work of one of the “architects” of the evolutionary synthesis, T. Dobzhansky; see Dobzhansky 1937), behavioral genetics (e.g., S. Benzer’s studies of the circadian clock mechanism, see Weiner 1999), biochemical genetics, as well as neuroscience.