On the Origin of Species.

In 1859 the British scientist Charles Darwin published On the Origin of Species by Means of Natural Selection, or, The Preservation of Favoured Races in the Struggle for Life, which argued that species of plants and animals, including human beings, were not changeless but evolved from other forms. Evolution occurred through survival of the fittest, in which individual organisms that were better adapted to their environment were more likely to survive long enough to reproduce and, therefore, pass on their characteristics, while less-well-adapted ones would not. While the idea of evolution was not entirely new to the scientific community, Darwin's hypothesis generated immediate controversy in Europe and the United States. The first printing of the book in Great Britain, consisting of 1,250 copies, sold out in one day; when the first American edition was published in 1860, its sales were also...