The Nazis believed that the "Aryan race" was superior to all other races because they were the most advanced. They used the idea of ​​eugenics to purify their race by killing anyone deemed inferior, such as Jews and people with disabilities. The belief that they were superior helped them justify the invasion of Europe as they viewed other races as inferior, therefore they believed they had the right to world domination. Furthermore, starting a war was considered necessary to create conflict as it creates survival of the fittest. This ideology caused World War II and approximately 60 million deaths. Eugenics also became influential in America when the American Breeders' Association was formed. The purpose of this organization was to protect the biological standards of the breed (Bowler 1984, p. 275). Many people who were believed to show signs of hereditary mental weakness were sterilized to prevent them from reproducing (Depew, 2010, p. 350). It also created fear towards immigrants of other races, as it was believed that good traits would mix with bad traits of other races and weaken over time (Depew, 2010, p. 350). Poverty was generally believed to be the consequence of diminished ability, so the poor were often targeted for sterilization. The lower social classes were often less intelligent but this cannot be attributed entirely to genetics, they often would