What are the origins of Eugenics?

Eugenics is defined by Oxford Dictionary as the "science of improving a human population by controlled breeding to increase the occurrence of desirable heritable characteristics."

The idea of Eugenics was developed largely by Francis Galton as a logical step onwards from Social Darwinism, as a method of improving the human race. However, he stopped short of advocating specific measures. Eugenics fell into disfavour only after its perversion by the Nazis in their idealization of blue eyed blonds as members of a master race, the Aryan, or perfect race.

Eugenics involves biological and/or social engineering with a view to improving the "biological quality" of the human species. In practice, it often meant "improving" the biology of the author's own nation or ethnic group. In Britain, it became interwoven with the quest for "national efficiency" in the period c.1901-1914.

The label "eugenics" was applied to a very wide range of ideas and practices, some of which had nothing to do with biology. For example, some early adherents of the psychometic intelligence theory claimed that the (British) nation could not afford to squander the talents of intelligent, poor kids and campaigned for the establishment of scholarships to enable them to study till age 18 and go on to university. They sometimes labelled this kind of scheme "eugenics".

Some of the ideas and practices were far from new and had no intellectual relationship to Social Darwinism. For example, in Ancient Sparta weak babies were exposed, abandoned and let to die.