Euthenics is the study of the improvement of human functioning and well-being by improvement of living conditions. Affecting the "improvement" through altering external factors such as education and the controllable environment, including the prevention and removal of contagious disease and parasites, environmentalism, education regarding employment, home economics, sanitation, and housing.Rose Field notes of the definition in a May 23, 1926 New York Times article, "the simplest being efficient living". A right to environment.The Flynn effect has been often cited as an example of euthenics. Another example is the steady increase in body size in industrialized countries since the beginning of the 20th century.
Euthenics is not normally interpreted to have anything to do with changing the composition of the human gene pool by definition, although everything that affects society has some effect on who reproduces and who does not.