Gerontology (from the Greek ?????, geron, "old man" and -?????, -logy, "study of"; coined by Ilya Ilyich Mechnikov in 1903) is the study of the social, psychological and biological aspects of aging. It is distinguished from geriatrics, which is the branch of medicine that studies the diseases of older adults. Gerontologists include researchers and practitioners in the fields of biology, medicine, nursing, dentistry, social work, physical and occupational therapy, psychology, psychiatry, sociology, economics, political science, architecture, pharmacy, public health, housing and anthropology.