Castle, William E. (William Ernest), 1867-1962

George Washington Corner worked as an anatomist, endocrinologist, and medical historian.

William Ernest Castle was a zoologist and geneticist. He received his PhD from Harvard (1895) and taught there until 1936. He continued research in the genetics of coat colors in horses at the University of California at Berkeley until 1961.

William Ernest Castle (1867-1962, APS 1910) was a zoologist and geneticist. A modest Midwesterner, he became one of the most influential geneticists of the first half of the twentieth century. He spent his career at Harvard University and the University of California, where he worked on patterns of inheritance in a variety of mammalian taxa. As a graduate student Castle was Charles B. Davenport’s (1866-1944, APS 1907) laboratory assistant. His dissertation, "The Early Embryology of Ciona intestinalis,” provided the first documentation of self-sterility in animals, and was published in the Bulletin of the Museum of Comparative Zoology in 1896. Castle was an ardent proponent of Mendelism, and he was also associated with the eugenics movement.

Castle was born in 1867 near Alexandria, Ohio, the son of William Augustus Castle and Sarah Fasset Castle. His parents were farmers, and young Castle’s learning about livestock may have sparked his interest in questions related to heredity and evolution. Castle graduated from Denison College in 1889 and half-heartedly began a career teaching Latin at the University of Ottawa in Kansas. Three years with the classics, however, convinced him that his love of natural science might afford a more interesting future. Applying to enter Harvard with the senior class in 1892, he received his A.B., A.M., and Ph.D. in three successive years, during the course of which he became laboratory assistant to Davenport and switched to zoology. His dissertation, "The Early Embryology of Ciona intestinalis," which he completed in 1895 under the direction of Edward L. Mark (1847-?, APS 1907) provided the first documentation of self-sterility in animals. The following year Castle married Clara Sears Bosworth. The couple had three children.

After brief appointments on the faculties at the University of Wisconsin and Knox College, Castle returned to Harvard in 1897 to begin what would become a forty year career in the department of zoology. Like Davenport, Castle soon acquired an interest in the problems of heredity. After around 1900, he abandoned his work in morphology and embryology to focus on the study of genetics. Turning to the question of the hereditary basis of sexual differentiation, he began large scale breeding experiments using mice and rats. However, the rediscovery of Gregor Mendel's theory of inheritance changed the tenor of his work. Castle soon emerged as one of the most ardent of the early Mendelians in the United States. Helping to construct the framework of Mendelism in America -- his article "Mendel's Law of Heredity,” which was published in the Proceedings of the American Academy of Arts and Sciences (1903), is often considered the first on the topic written by an American -- Castle applied his experimental skills to a variety of fundamental problems in mammalian genetics ranging from studies of the selection of Mendelian characters to the effects of inbreeding to linkage and gene mapping. In one of his best known and characteristically elegant experiments, conducted in 1909, he and John C. Phillips (1876-1938) transplanted the ovaries from a black guinea pig into an albino female and mated that female to an albino male. The progeny of the union were all black, neatly demonstrating that it was the genes, not the soma, that carried hereditary information. While best known for his work on mammals, he was also the first to use Drosophila for genetic experimentation, the organism that became synonymous with the work of Thomas Hunt Morgan (1866-1945, APS 1915). Although Castle strongly influenced the development of Mendelian studies in the United States, he at times questioned the view that all inheritance could be explained in Mendelian terms.

Castle conducted much of his work as a research associate at the Station for Experimental Evolution at Cold Spring Harbor Laboratory. The Station, later renamed the Department of Genetics, was directed by Davenport and financed by the Carnegie Institute of Washington. The institution funded Castle’s work from 1904 to 1943. In 1908 the Bussey Institution at Harvard was reorganized as a graduate school for applied sciences, and Castle relocated his lab, his mice and guinea pigs there. The arrival of Edward M. East (1879-1938, APS 1916) the following year transformed the Bussey into one of the two most active early centers of genetic study in the country. Castle served as Director of the Bussey until his retirement in 1936, at which time the institution was shuttered for economic reasons. Castle's influence, however, continued through his many graduate students who went on to careers in genetics, including Clarence C. Little (1888-1971), Leslie C. Dunn (1893-1974, APS 1943), Gregory Pincus (1903-1967), George D. Snell (1903-1996, APS 1985), Sewall Wright (1889-1988, APS 1932), and Sheldon C. Reed (1910-2003).

Castle’s influence was also felt through his association with scientific eugenics during the 1920s, even though he was skeptical of the feasibility and desirability of eugenics to improve the human race. In 1916 he argued that human society could not be managed like a farm; subsequently he also claimed that genes did not determine social status, and that negative eugenics violated individual liberty. Nevertheless, his criticism of eugenics was rather conservative. For example, he believed that there could be social objections to the mixture of different races, and he agreed that the segregation and sterilization of the “feebleminded” was desirable. Unlike other notable scientists who eventually distanced themselves from the eugenics movement, such as Thomas Hunt Morgan and Herbert Spencer Jennings, Castle remained consistent in his advocacy, possibly because he did not want to offend his friend Davenport. He served on the advisory board of the Eugenics Record Office that was established by Davenport at Cold Spring Harbor in 1910, and he was a founder of the eugenically connected American Breeders' Association that was reorganized into the American Eugenics Society in 1913. Moreover, his textbook Genetics and Eugenics (1916) was widely used and went through four editions in fourteen years.

After receiving emeritus status from Harvard, Castle moved to the West Coast to become a research associate at the University of California, Berkeley. He spent an additional twenty five years in research, focusing on the genetics of coat coloration in horses. The last of his 242 scientific papers was published in 1961 at the age of 94. During his long career, he served as an officer for a number of professional societies and received his share of awards, including election to the American Academy of Arts and Sciences (1900), the American Philosophical Society (1910), the National Academy of Sciences (1915), the Genetics Society of America, and the American Genetics Association, which he served as vice president in 1924. He was also president of the American Society of Naturalists in 1919, and he was the first recipient of the Kimber Genetics Award of the National Academy of Sciences in 1955. Finally, he was a founder of the journal Genetics and a member of the editorial board of the Journal of Experimental Zoology from its initial issue in 1904 until his death in 1962.