The social effects of evolutionary thought have been considerable. As the scientific explanation of life's diversity has developed, it has often displaced alternative, sometimes very widely held, explanations. Because the theory of evolution includes an explanation of humanity's origins, it has had a profound impact on human societies. Some have vigorously denied acceptance of the scientific explanation due to its perceived religious implications (e.g. its implied rejection of the special creation of humans presumably described in the Bible). This has led to a vigorous conflict between creation and evolution in public education, primarily in the United States. Evolution and ethics 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 more smart 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