On the Tendency of Species to form Varieties; and on the Perpetuation of Varieties and Species by Natural Means of Selection Letter" from Darwin to Asa Gray. This was the first announcement of the Darwin – Wallace theory of evolution by natural selection; the papers appeared in print on 20 August 1858. The presentation of the papers spurred Darwin to write a condensed "abstract" of his "big book" on "Natural Selection". This was published in November 1859 as "On the Origin of Species". On the voyage of the "Beagle" the young Charles Darwin took a break between graduating and starting his career as a clergyman to study the natural history of South America, an interest he had developed at the University
On the Origin of Species disperse across oceans to colonise distant islands. By 1856, his theory was much more sophisticated, with a mass of supporting evidence. In his autobiography, Darwin said he had "gained much by my delay in publishing from about 1839, when the theory was clearly conceived, to 1859; and I lost nothing by it". On the first page of his 1859 book he noted that, having begun work on the topic in 1837, he had drawn up "some short notes" after five years, had enlarged these into a sketch in 1844, and "from that period to the present day I have steadily