ABSTRACT
Charles Darwin’s epoch-making claim in On the Origin of Species (1859) was not that species change over time or give rise to other species. Such ideas had already been advanced by Enlightenment thinkers such as Erasmus Darwin and Jean-Baptiste Lamarck. Lamarck in particular had put forth a comprehensive evolutionary theory and claimed in his Philosophie zoologique (1809) that humans had descended from a kind of ape. What set Charles Darwin apart from earlier evolutionists was his distinctive mode of explanation. Darwin summarizes this idea as follows:
Variations, however slight and from whatever cause proceeding, if they be in any degree profitable to the individuals of a species, in their infinitely complex relations to other organic beings and to their physical conditions of life, will tend to the preservation of such individuals, and will generally be inherited by the offspring. The offspring, also, will thus have a better chance of surviving, for, of the many individuals of a species which are periodically born, but a small number can survive. I have called this principle, by which each slight variation, if useful, is preserved, by the term Natural Selection.1
