The theory of evolution by natural selection has also been adopted as a foundation for various ethical and social systems, such as
social Darwinism, an idea that preceded the publication of
The Origin of Species, popular in the 19th century, which holds that "the
survival of the fittest" (a phrase coined in 1851 by Herbert Spencer, 8 years before Darwin published his theory of evolution) explains and justifies differences in wealth and success among societies and people. A similar interpretation was one created by Darwin's cousin,
Francis Galton, known as
eugenics, which claimed that human civilization was subverting natural selection by allowing the less bright and less healthy to survive and out-breed the smarter and more healthy. Later advocates of this theory suggested radical and often coercive social measures in an attempt to "correct" this imbalance.
Thomas Huxley spent much time demonstrating through a series of thought experiments that it would not only be immoral, but impossible.
Stephen Jay Gould and others have argued that social Darwinism is based on misconceptions of evolutionary theory, and many ethicists regard it as a case of the
is-ought problem. After the atrocities of
the Holocaust became linked with eugenics, it greatly fell out of favor with public and scientific opinion, though it was never universally accepted by either, and at no point in Nazi literature is Charles Darwin or the scientific theory of evolution mentioned. In his book
The End of Faith,
Sam Harris argues that Nazism was largely a continuation of
Christian anti-Semitism. Jim Walker compiled a list of 129 quotes from
Mein Kampf in which Hitler described himself as a Christian, or mentioned God, Jesus or a biblical passage. Some argue that six million of the people killed during the Holocaust were killed because of their religion (Judaism) not their race, "strength," or any reason with an obvious link to the mechanism of Darwinian evolution. Hitler often used Christian beliefs like, "Jews killed Jesus," to justify his anti-Semitism. The notion that humans share ancestors with other animals has also affected how some people view the relationship between humans and other species. Many proponents of
animal rights hold that if animals and humans are of the same nature, then rights cannot be distinct to humans. Charles Darwin, in fact, considered "
sympathy" to be one of the most important
moral virtues — and that it was, indeed, a product of natural selection and a trait beneficial to social animals (including
humans). Darwin further argued that the most "sympathetic" societies would consequently be the most "successful." He also stated that our sympathy should be extended to "all sentient beings": ==Evolution and religion==