Charles Robert Darwin FRS (12 February 1809 – 19 April 1882) was an English naturalist who realised that all species of life have evolved over time from common ancestors, and published compelling supporting evidence of this in his 1859 book On the Origin of Species in which he presented his scientific theory that this branching pattern of evolution resulted from a process that he called natural selection. The fact that evolution occurs became accepted by the scientific community and much of the general public in his lifetime, but it was not until the emergence of the modern evolutionary synthesis from the 1930s to the 1950s that a broad consensus developed that natural selection was the basic mechanism of evolution. In modified form, Darwin's scientific discovery is the unifying theory of the life sciences, explaining the diversity of life.
Darwin's early interest in nature led him to neglect his course in medicine at Edinburgh University and instead help to investigate marine invertebrates, then the University of Cambridge encouraged a passion for natural science. His five-year voyage on HMS Beagle established him as an eminent geologist whose observations and theories supported Charles Lyell's uniformitarian ideas, and publication of his journal of the voyage made him famous as a popular author.
Puzzled by the geographical distribution of wildlife and fossils he collected on the voyage, Darwin investigated the transmutation of species and conceived his theory of natural selection in 1838. Although he discussed his ideas with several naturalists, he needed time for extensive research and his geological work had priority. He was writing up his theory in 1858 when Alfred Russel Wallace sent him an essay which described the same idea, prompting immediate joint publication of both of their theories. Darwin's work established evolutionary descent with modification as the dominant scientific explanation of diversification in nature. In 1871 he examined human evolution and sexual selection in The Descent of Man, and Selection in Relation to Sex, followed by The Expression of the Emotions in Man and Animals. His research on plants was published in a series of books, and in his final book, he examined earthworms and their effect on soil.
In recognition of Darwin's pre-eminence as a scientist, he was one of only five 19th-century UK non-royal personages to be honoured by a state funeral, and was buried in Westminster Abbey, close to John Herschel and Isaac Newton.
When the Beagle returned on 2 October 1836, Darwin was already a celebrity in scientific circles as in December 1835 Henslow had fostered his former pupil's reputation by giving selected naturalists a pamphlet of Darwin's geological letters. Darwin visited his home in Shrewsbury and saw relatives, then hurried to Cambridge to see Henslow, who advised on finding naturalists available to catalogue the collections and agreed to take on the botanical specimens. Darwin's father organised investments, enabling his son to be a self-funded gentleman scientist, and an excited Darwin went round the London institutions being fêted and seeking experts to describe the collections. Zoologists had a huge backlog of work, and there was a danger of specimens just being left in storage.
Charles Lyell eagerly met Darwin for the first time on 29 October and soon introduced him to the up-and-coming anatomist Richard Owen, who had the facilities of the Royal College of Surgeons to work on the fossil bones collected by Darwin. Owen's surprising results included gigantic extinct sloths, a near complete skeleton of the unknown Scelidotherium and a hippopotamus-sized rodent-like skull named Toxodon resembling a giant capybara. The armour fragments were from Glyptodon, a huge armadillo-like creature as Darwin had initially thought. These extinct creatures were related to living species in South America.
In mid-December Darwin took lodgings in Cambridge to organise work on his collections and rewrite his Journal. He wrote his first paper, showing that the South American landmass was slowly rising, and with Lyell's enthusiastic backing read it to the Geological Society of London on 4 January 1837. On the same day, he presented his mammal and bird specimens to the Zoological Society. The ornithologist John Gould soon announced that the Galapagos birds that Darwin had thought a mixture of blackbirds, "gros-beaks" and finches, were, in fact, twelve separate species of finches. On 17 February Darwin was elected to the Council of the Geological Society, and Lyell's presidential address presented Owen's findings on Darwin's fossils, stressing geographical continuity of species as supporting his uniformitarian ideas.
Early in March, Darwin moved to London to be near this work, joining Lyell's social circle of scientists and experts such as Charles Babbage, who described God as a programmer of laws. John Herschel's letter on the "mystery of mysteries" of new species was widely discussed, with explanations sought in laws of nature, not ad hoc miracles. Darwin stayed with his freethinking brother Erasmus, part of this Whig circle and close friend of writer Harriet Martineau who promoted Malthusianism underlying the controversial Whig Poor Law reforms to stop welfare from causing overpopulation and more poverty. As a Unitarian she welcomed the radical implications of transmutation of species, promoted by Grant and younger surgeons influenced by Geoffroy, but anathema to Anglicans defending social order.
In their first meeting to discuss his detailed findings, Gould told Darwin that the Galápagos mockingbirds from different islands were separate species, not just varieties, and the finch group included the "wrens". Darwin had not labelled the finches by island, but from the notes of others on the Beagle, including FitzRoy, he allocated species to islands. The two rheas were also distinct species, and on 14 March Darwin announced how their distribution changed going southwards.
A page of hand-written notes, with a sketch of branching lines.
In mid-July 1837 Darwin started his "B" notebook on Transmutation of Species, and on page 36 wrote "I think" above his first evolutionary tree.
By mid-March, Darwin was speculating in his Red Notebook on the possibility that "one species does change into another" to explain the geographical distribution of living species such as the rheas, and extinct ones such as the strange Macrauchenia, resembling a giant guanaco. His thoughts on lifespan, asexual reproduction and sexual reproduction developed in his "B" notebook around mid-July on to variation in offspring "to adapt & alter the race to changing world" explaining the Galápagos tortoises, mockingbirds and rheas. He sketched branching descent, then a genealogical branching of a single evolutionary tree, in which "It is absurd to talk of one animal being higher than another", discarding Lamarck's independent lineages progressing to higher forms.
Preparing the theory of Natural Selection for Publication
Darwin now had the framework of his theory of natural selection "by which to work", as his "prime hobby". His research included animal husbandry and extensive experiments with plants, finding evidence that species were not fixed and investigating many detailed ideas to refine and substantiate his theory. For fifteen years this work was in the background to his main occupation of writing on geology and publishing expert reports on the Beagle collections.
When FitzRoy's Narrative was published in May 1839, Darwin's Journal and Remarks was such a success as the third volume that later that year it was published on its own. Early in 1842, Darwin wrote about his ideas to Charles Lyell, who noted that his ally "denies seeing a beginning to each crop of species".
Darwin's book The Structure and Distribution of Coral Reefs on his theory of atoll formation was published in May 1842 after more than three years of work, and he then wrote his first "pencil sketch" of his theory of natural selection. To escape the pressures of London, the family moved to rural Down House in September. On 11 January 1844 Darwin mentioned his theorising to the botanist Joseph Dalton Hooker, writing with melodramatic humour "it is like confessing a murder". Hooker replied "There may in my opinion have been a series of productions on different spots, & also a gradual change of species. I shall be delighted to hear how you think that this change may have taken place, as no presently conceived opinions satisfy me on the subject."
Path covered in sandy gravel winding through open woodland, with plants and shrubs growing on each side of the path.
Darwin's "sandwalk" at Down House was his usual "Thinking Path".
By July, Darwin had expanded his "sketch" into a 230-page "Essay", to be expanded with his research results if he died prematurely. In November the anonymously published sensational best-seller Vestiges of the Natural History of Creation brought wide interest in transmutation. Darwin scorned its amateurish geology and zoology, but carefully reviewed his own arguments. Controversy erupted, and it continued to sell well despite contemptuous dismissal by scientists.
Darwin completed his third geological book in 1846. He now renewed a fascination and expertise in marine invertebrates, dating back to his student days with Grant, by dissecting and classifying the barnacles he had collected on the voyage, enjoying observing beautiful structures and thinking about comparisons with allied structures. In 1847, Hooker read the "Essay" and sent notes that provided Darwin with the calm critical feedback that he needed, but would not commit himself and questioned Darwin's opposition to continuing acts of creation.
In an attempt to improve his chronic ill health, Darwin went in 1849 to Dr. James Gully's Malvern spa and was surprised to find some benefit from hydrotherapy. Then in 1851 his treasured daughter Annie fell ill, reawakening his fears that his illness might be hereditary, and after a long series of crises she died.
In eight years of work on barnacles (Cirripedia), Darwin's theory helped him to find "homologies" showing that slightly changed body parts served different functions to meet new conditions, and in some genera he found minute males parasitic on hermaphrodites, showing an intermediate stage in evolution of distinct sexes. In 1853 it earned him the Royal Society's Royal Medal, and it made his reputation as a biologist. He resumed work on his theory of species in 1854, and in November realised that divergence in the character of descendants could be explained by them becoming adapted to "diversified places in the economy of nature".
Publication of the theory of Natural Selection
By the start of 1856, Darwin was investigating whether eggs and seeds could survive travel across seawater to spread species across oceans. Hooker increasingly doubted the traditional view that species were fixed, but their young friend Thomas Henry Huxley was firmly against evolution. Lyell was intrigued by Darwin's speculations without realising their extent. When he read a paper by Alfred Russel Wallace on the Introduction of species, he saw similarities with Darwin's thoughts and urged him to publish to establish precedence. Though Darwin saw no threat, he began work on a short paper. Finding answers to difficult questions held him up repeatedly, and he expanded his plans to a "big book on species" titled Natural Selection. He continued his researches, obtaining information and specimens from naturalists worldwide including Wallace who was working in Borneo. The American botanist Asa Gray showed similar interests, and on 5 September 1857 Darwin sent Gray a detailed outline of his ideas including an abstract of Natural Selection. In December, Darwin received a letter from Wallace asking if the book would examine human origins. He responded that he would avoid that subject, "so surrounded with prejudices", while encouraging Wallace's theorising and adding that "I go much further than you."
Darwin's book was half way when, on 18 June 1858, he received a paper from Wallace describing natural selection. Shocked that he had been "forestalled", Darwin sent it on to Lyell, as requested, and, though Wallace had not asked for publication, he suggested he would send it to any journal that Wallace chose. His family was in crisis with children in the village dying of scarlet fever, and he put matters in the hands of Lyell and Hooker. They decided on a joint presentation at the Linnean Society on 1 July of On the Tendency of Species to form Varieties; and on the Perpetuation of Varieties and Species by Natural Means of Selection; however, Darwin's baby son died of the scarlet fever and he was too distraught to attend.
There was little immediate attention to this announcement of the theory; the president of the Linnean Society remarked in May 1859 that the year had not been marked by any revolutionary discoveries. Only one review rankled enough for Darwin to recall it later; Professor Samuel Haughton of Dublin claimed that "all that was new in them was false, and what was true was old." Darwin struggled for thirteen months to produce an abstract of his "big book", suffering from ill health but getting constant encouragement from his scientific friends. Lyell arranged to have it published by John Murray.
On the Origin of Species proved unexpectedly popular, with the entire stock of 1,250 copies oversubscribed when it went on sale to booksellers on 22 November 1859. In the book, Darwin set out "one long argument" of detailed observations, inferences and consideration of anticipated objections. His only allusion to human evolution was the understatement that "light will be thrown on the origin of man and his history".