What is the significance of On the Origin of Species?

Charles Darwin (1809-1882) first proposed a theory of evolution based on natural selection in his treatise On the Origin of Species. The publication of On the Origin of Species ushered in a new era in our thinking about the nature of man. The intellectual revolution it caused and the impact it had on man's concept of himself and the world were greater than those caused by the works of Isaac Newton 0642-1727) and other individuals. The effect was immediate-the first edition sold out on the day of publication (November 24,1859). Origin has been referred to as "the book that shook the world." Every modern discussion of man's future, the population explosion, the struggle for existence, the purpose of man and the universe, and man's place in nature rests on Darwin.
The work was a product of his analyses and interpretations of his findings from his voyages on the HMS Beagle. In Darwin's day the prevailing explanation for organic diversity was the story of creation in the book of Genesis in the Bible. Origin was the first publication to present scientifically sound, well-organized evidence for the theory of evolution. Darwin's theory was based on natural selection in which the best,or fittest, individuals survive more often than those who are less fit. If there is a differ-450 ence in the genetic endowment among these individuals that correlates with fitness,the species will change over time and will eventually resemble more closely (as a group) the fittest individuals. It is a two-step process: the first consists of the production of variation, and the second, of the sorting of this variability by natural selection in which the favorable variations tend to be preserved.