Wallace
In the spring of 1856 Lyell was shaken by a paper "On the Law which has Regulated the Introduction of New Species" published in the Annals and Magazine of Natural History and written by Alfred Russel Wallace, a naturalist working in Borneo. This started Lyell rethinking his opposition to evolution, and he tipped off Darwin who appears to have taken little notice of Wallace's guarded comments at this point. Darwin was now working out a strategy for presenting his theory, and he finally spelt out the full details of Natural Selection to Lyell. While Lyell could not fully accept this, he urged Darwin to publish to establish priority. Darwin was now torn between the desire to set out a full and convincing account, and the pressure to quickly produce a short paper. He ruled out exposing himself to an editor or counsel, as would have been required to publish in an academic journal. On 14 May 1856 he began a "sketch" account.
By July Darwin had decided to produce a full technical treatise on species. Lyell seemed to be coming round to Darwin's ideas, but in private was agonising over the social implications if humans had animal ancestry, particularly now that race was becoming an issue, with Robert Knox describing races as different species and warning of racial wars. Hooker's verdict on the growing manuscript was "incomparably more favourable" than Darwin had anticipated, while Darwin tried to put over the point that "external conditions do extremely little", it was the selection of "chance" variations that produced new species.
Darwin's experiments on how species spread were now extended to considering how animals such as snails could be carried on birds' feet, and seeds in birds' droppings. His tenth child, Charles Waring Darwin was born on 6 December apparently without his full share of intelligence, renewing fears of inbreeding and hereditary defects, a topic that he covered in principle in his book.
On 23 February 1857 the Darwins were visited for lunch by Robert FitzRoy, who had been the captain of HMS Beagle during Darwin's voyage, together with his second wife, his first wife and his only daughter having died.
Darwin's cousin William Darwin Fox remained a mainstay, warning him against overworking on his huge book and recommending a holiday, but Darwin was immersed in his experiments and his writing. "I wish I could set less value on the bauble fame, either present or posthumous... yet, if I know myself, I would work just as hard, though with less gusto, if I knew that my Book would be published for ever anonymously."
Read more about this topic: Publication Of Darwin's Theory