Icie Gertrude Macy Hoobler was born on July 23, 1892, on a four-hundred-acre farm five miles east of Gallatin in Daviess County, Missouri, the third of four children of Perry Macy and Ollevia Elvaree Macy, née Critten. The land had been in the family since her great-grandfather acquired it in 1834. Childhood on that farm shaped her. She watched livestock mature, walked the fields, and absorbed the practical chemistry of soil, feed, and growth. A trip into the Arkansas mountains, where she saw sick children living in poverty, fixed her attention on the health of the young. She attended a one-room schoolhouse and then, at her father’s insistence, spent three years at Central College for Women in Lexington, Missouri, studying music. She had little talent for performance. A biology teacher, Lily Egbert, encouraged her scientific curiosity. She completed a Bachelor of Arts in 1914, having shifted toward English studies, and then went to the University of Chicago.
At Chicago she earned a Bachelor of Science in chemistry in 1916, working under Julius Stieglitz and taking courses that brought her into contact with Robert A. Millikan and A. A. Michelson. Her advisor sent her to the University of Colorado at Boulder as an assistant instructor in freshman chemistry, one of the first women in that role. There she completed a Master of Arts in 1918. One thesis improved a test for cyanide in autopsies and became her first published paper; another concerned the extraction of tungstic acid from tungsten ores. With recommendations from her Chicago and Colorado mentors she entered the Department of Physiological Chemistry at Yale’s Sheffield Scientific School. Housing near campus was hard to find because landlords regarded women graduate students as bothersome. She persisted and in 1920 received the Ph.D., the fourth woman to do so in that department. Her advisor was Lafayette B. Mendel. The dissertation examined the physiology and toxicity of cottonseed, a wartime substitute for wheat flour that had produced problems in animal feed.
After a period of rest following nephritis and a brief teaching appointment at the University of California, Berkeley, in food chemistry, she accepted in 1923 the directorship of the Nutrition Research Project at the Merrill-Palmer School for Motherhood and Child Development in Detroit, in association with Children’s Hospital of Michigan. The assignment was to organize, equip, and run a laboratory that would support teaching and produce original knowledge about maternal and child health. In 1931 the laboratory and its staff moved under the newly created Children’s Fund of Michigan, a twenty-five-year foundation established by Senator James J. Couzens. Hoobler became director of the Fund’s research division and held that post until 1954, remaining a consultant until 1974. Under her leadership the laboratory published more than three hundred journal articles and a series of monographs and books.
The work was systematic and longitudinal. She and her colleagues measured the metabolism of women through pregnancy and lactation, mapped the changing composition of human milk, compared human, cow, and goat milks, and followed the chemical growth of infants and children. They documented mineral balances, the chemistry of the red blood cell, and the effects of diet on the nutrient content of mother’s milk. They helped establish the quantity of vitamin D that could safely be added to milk to prevent rickets without toxicity. Studies linked prenatal nutrition to birth weight, growth trajectories, and the incidence of defects, and they showed how economic status shaped those outcomes. During the Depression the laboratory not only published findings but helped design programs that supplied food and information to mothers. In the Second World War she served on the National Research Council’s Food and Nutrition Board, of which she was a charter member, remaining on the board for fourteen years and chairing work on maternal and child feeding. Two reports that drew heavily on her data contributed to wartime and postwar dietary standards. Her three-volume Nutrition and Chemical Growth in Childhood (1942–1951) assembled evaluation methods, original data, and interpretation. Other volumes included The Composition of Milks and Hidden Hunger. Late in life she published an autobiography, Boundless Horizons: Portrait of a Pioneer Woman Scientist (1982).
Recognition accumulated. In 1931 she became the first woman to chair a local section of the American Chemical Society (Detroit) and also chaired the society’s Division of Biological Chemistry. She was a charter member, secretary, and, in 1944, president of the American Institute of Nutrition. She received the Borden Award of the American Home Economics Association in 1939, the Frances P. Garvan Medal of the American Chemical Society in 1945 (sometimes dated 1946) for contributions to the nutrition of growth, mineral metabolism, and the chemistry of the red blood cell, the Norlin Award of the University of Colorado, and the Osborne and Mendel Award of the American Institute of Nutrition in 1952. She was the first woman member of the Detroit Engineering Society, president of the Michigan Academy of Arts, Sciences and Letters, a fellow of the American Institute of Chemists, the American Association for the Advancement of Science, and the American Public Health Association, and a member of eighteen scientific societies. Honorary degrees came from Wayne State University and Grand Valley State College, an institution she helped found. In 1984 she was inducted into the Michigan Women’s Hall of Fame. Across her career the laboratory and she received some twenty-two citations and awards.
Personal life was marked by both loss and companionship. In 1917 her sister Ina Wynne died of childbed fever; Hoobler helped raise Ina’s daughters, Christine and Helen. In 1938, at forty-six, she married B. Raymond Hoobler, chief of staff at Children’s Hospital of Michigan and a pediatrician trained under Emmett Holt. He died in 1943 after five years of marriage. She later wrote that those years contained the happiness of a much longer union. She returned to Gallatin in 1982 and died there on January 6, 1984, at ninety-one.
Hoobler’s career unfolded in a period when laboratories, housing, and professional societies often treated women as exceptions. She met those barriers with persistence rather than rhetoric, producing data that changed clinic practice, fortified milk, informed the later WIC program, and gave later investigators reference values for mineral and energy metabolism in the growing child. She drew inspiration from earlier women in science—Elizabeth Blackwell, Maria Mitchell, Ellen Swallow Richards—and observed near the end of her life that many overt obstacles had fallen while subtler ones remained. The record she left is quantitative, patient, and directed at the most ordinary and most consequential of human processes: how a mother and a child are fed.