On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life is a work of scientific literature by the English naturalist Charles Darwin that is considered to be the foundation of evolutionary biology. It was published on 24 November 1859. Darwin's book introduced the scientific theory that populations evolve over the course of generations through a process of natural selection, although Lamarckism was also included as a mechanism of lesser importance.