100 Years Ago: Walter Sutton and the Chromosome Theory of Heredity

EVERY student of elementary genetics learns of Walter Sutton (1877–1916). Sutton was the first to point out that chromosomes obey Mendel's rules—the first clear argument for the chromosome theory of heredity. This year marks the centennial of Sutton's (1902) historic paper, surely the most important genetic event in that year. Sutton worked with grasshopper chromosomes, and it was in this paper that he showed that chromosomes occur in distinct pairs, which segregate at meiosis. His concluding statement reads: “I may finally call attention to the probability that the association of paternal and maternal chromosomes in pairs and their subsequent separation during the reducing division … may constitute the physical basis of the Mendelian law of heredity” (p. 39). Sutton, a Kansas farm boy, had been a student of C. E. McClung (1870–1946), a prairie pioneer cytologist at the University of Kansas. McClung took advantage of the great abundance of grasshoppers in that state to make them pivotal for cytological study and to found a school of grasshopper cytologists. In 1912 he moved to the University of Pennsylvania to continue his distinguished career. One of the best known of his students was W. R. B. Robertson, of “Robertsonian translocations.”