Robert Calvin Hardin was born March 25, 1913 in Portland, Oregon. He graduated from high school in 1930 at Buffalo Center, Iowa. He received a B.S. degree in medicine in 1935 and the M. D. in 1937, both at the State University of Iowa. From 1939 to 1941, Hardin was a resident physician at the University Hospital. During World War II, he served in the European Theatre as a U. S. Army Lieutenant Colonel and received the Legion of Merit award for the blood collection work he performed.

In 1945, Hardin continued his forty-year teaching career at the State University of Iowa as instructor in Theory & Practice of Medicine, later named the Department of Internal Medicine. He was named full professor in 1953. From 1952 until 1980, Hardin served as vice president and dean of Veterans Administration Medical Center, which he helped establish. In 1949 Hardin coauthored the book, Blood Transfusion, with doctors Elmer L. DeGowin, founder of the University Hospital blood bank, and John B. Alsever, a haematologist with the U. S. Office of Civil Defense. Hardin was also a specialist in the treatment of diabetes. He served as the dean of the College of Medicine from 1962 to 1970 and was succeeded by Dr. John W. Eckstein. Hardin retired in 1983. He was involved in planning the Health Sciences Library, which was constructed in 1974 and renamed the Hardin Library for Health Sciences in 1988.

Hardin married Velma Holets in December 1939 and they had two children. Hardin died January 2, 1988.