Charles Darwin is identified as a social Darwinist whose theories on natural selection were applied to human societies in the late 19th century. In his book The Descent of Man, Darwin expressed concerns that humanitarian efforts for the sick and poor were interfering with the survival of the fittest. The full title of his earlier work, The Origin of Species, is cited to highlight its explicit mention of the "preservation of favored races," suggesting a scientific foundation for racial extermination.