In 1859, Charles Darwin published On the Origin of Species, a book about the evolution of non-human animals by natural selection. In its wake, a political idea arose — eugenics. Reading Darwin's book, Sir Francis Galton proposed that humans should be bred to give more "suitable" characteristics a "better chance of prevailing." Today, producer Rebecca Ramirez talks to Adam Rutherford about his new book, Control: The Dark History and Troubling Present of Eugenics, which traces the inextricable link between political ideology and science, and the enduring shadow of eugenics.