Seymour Benzer helped turn the study of behavior into an experimental problem in genetics. With Ronald J. Konopka, he reported fruit-fly mutations that abolished daily rhythmicity or changed its period to approximately 19 or 28 hours. Both adult emergence and individual locomotor activity were affected.[ref]
Clock Mutants of Drosophila melanogaster by Ronald J. Konopka and Seymour Benzer. 1971, abstract and printed pp. 2112–2113
Flies were tested in constant darkness, while infrared monitoring recorded individual movement without imposing a daily light cycle. Persistence of altered timing under those conditions supported an internal circadian rhythm mechanism, rather than merely a different immediate response to the lamps switching on. The mutations mapped to the same functional gene on the X chromosome.[ref]
Clock Mutants of Drosophila melanogaster by Ronald J. Konopka and Seymour Benzer. Materials and Methods, locomotor apparatus; Results, mapping and complementation
Portrait of Seymour Benzer
. Caltech photograph identifying Benzer beside an enlarged fruit-fly model. Source.