Claude Bernard was a French physiologist. Historian I. Bernard Cohen of Harvard University called Bernard "one of the greatest of all men of science". He originated the term milieu intérieur, and the associated concept of homeostasis.

Walter Bradford Cannon was an American physiologist, professor and chairman of the Department of Physiology at Harvard Medical School. He coined the term "fight or flight response", and developed the theory of homeostasis. He popularized his theories in his book The Wisdom of the Body, first published in 1932.