Natural Selection

English naturalist Charles Darwin presented natural selection in his November 24, 1859 book On the Origin of Species (first printing: 1,250 copies), introducing the scientific theory that populations evolve through natural means from earlier ancestors. Darwin began formulating his ideas in the late 1830s—a visit to the Galapagos Islands in 1835 helped crystallize his thinking—but worked quietly for twenty years, amassing evidence. Natural selection describes how variations within species lead to differential survival and reproduction, causing advantageous traits to become more common across generations. While most scientists quickly accepted evolution and common descent, natural selection took decades to gain acceptance.