Many anti-evolutionists have also said evolution has led to "social Darwinism," a concept that said humans struggle to survive in society and only the fittest will survive -- just as the fittest survive in the biological world. Social Darwinism has been viewed as the impetus behind imperialist or racist politics such as Nazism. "Eugenics" was another controversial doctrine that evolved out of Darwin's theory; eugenics says people who are successful are genetically superior to the lower classes of society.
Bryan believed that wars had been caused by the social applications of Darwinism. He feared that Social Darwinian ideas might become widespread if taught to young people, a big reason why he agreed to defend the state in the Scopes trial.