eugenics,the selection of desired heritable characteristics in order to improve future generations, typically in reference to humans. The term eugenics was coined in 1883 by the British explorer and natural scientist Francis Galton, who, influenced by Charles Darwins theory of natural selection, advocated a system that would allow the more suitable races or strains of blood a better chance of prevailing speedily over the less suitable. Social Darwinism, the popular theory in the late 19th century that life for humans in society was ruled by survival of the fittest, helped advance eugenics into serious scientific study in the early 1900s. By World War I, many scientific authorities and political leaders supported eugenics. However, it ultimately failed as a science in the 1930s and 40s, when the assumptions of eugenicists became heavily criticized and the Nazis used eugenics to support the extermination of entire races.

Although eugenics as understood today dates from the late 19th century, efforts to select matings in order to secure offspring with desirable traits date from ancient times. Platos Republic (c. 378 bce) depicts a society where efforts are undertaken to improve human beings through selective breeding. Later, Italian philosopher and poet Tommaso Campanella, in City of the Sun (1623), described a utopian community in which only the socially elite are allowed to procreate. Galton, in Hereditary Genius (1869), proposed that a system of arranged marriages between men of distinction and women of wealth would eventually produce a gifted race. In 1865, the basic laws of heredity were discovered by the father of modern genetics, Gregor Mendel. His experiments with peas demonstrated that each physical trait was the result of a combination of two units (now known as genes) and could be passed from one generation to another. However, his work was largely ignored until its rediscovery in 1900. This fundamental knowledge of heredity provided eugenicistsincluding Galton, who influenced his cousin Charles Darwinwith scientific evidence to support the improvement of humans through selective breeding.

The advancement of eugenics was concurrent with an increasing appreciation of Charles Darwins account for change or evolution within societywhat contemporaries referred to as Social Darwinism. Darwin had concluded his explanations of evolution by arguing that the greatest step humans could make in their own history would occur when they realized that they were not completely guided by instinct. Rather, humans, through selective reproduction, had the ability to control their own future evolution. A language pertaining to reproduction and eugenics developed, leading to terms such as positive eugenics, defined as promoting the proliferation of good stock, and negative eugenics, defined as prohibiting marriage and breeding between defective stock. For eugenicists, nature was far more contributory than nurture in shaping humanity.

During the early 1900s, eugenics became a serious scientific study pursued by both biologists and social scientists. They sought to determine the extent to which human characteristics of social importance were inherited. Among their greatest concerns were the predictability of intelligence and certain deviant behaviours. Eugenics, however, was not confined to scientific laboratories and academic institutions. It began to pervade cultural thought around the globe, including the Scandinavian countries, most other European countries, North America, Latin America, Japan, China, and Russia. In the United States, the eugenics movement began during the Progressive Era and remained active through 1940. It gained considerable support from leading scientific authorities such as zoologist Charles B. Davenport, plant geneticist Edward M. East, and geneticist and Nobel Prize laureate Hermann J. Muller. Political leaders in favour of eugenics included U.S. President Theodore Roosevelt, Secretary of State Elihu Root, and Associate Justice of the Supreme Court John Marshall Harlan. Internationally, there were many individuals whose work supported eugenic aims, including British scientists J.B.S. Haldane and Julian Huxley and Russian scientists Nikolay K. Koltsov and Yury A. Filipchenko.

More here:

eugenics | genetics | Britannica.com