Works

Darwin was a prolific writer. Even without publication of his works on evolution, he would have had a considerable reputation as the author of The Voyage of the Beagle, as a geologist who had published extensively on South America and had solved the puzzle of the formation of coral atolls, and as a biologist who had published the definitive work on barnacles. While The Origin of Species dominates perceptions of his work, The Descent of Man, and Selection in Relation to Sex and The Expression of Emotions in Man and Animals had considerable impact, and his books on plants including The Power of Movement in Plants were innovative studies of great importance, as was his final work on The Formation of Vegetable Mould Through the Action of Worms.

Commemoration

In 1881 Darwin was an eminent figure, still working on his contributions to evolutionary thought that had had an enormous effect on many fields of science.

During Darwin's lifetime, many geographical features were given his name. An expanse of water adjoining the Beagle Channel was named Darwin Sound by Robert FitzRoy after Darwin's prompt action, along with two or three of the men, saved them from being marooned on a nearby shore when a collapsing glacier caused a large wave that would have swept away their boats, and the nearby Mount Darwin in the Andes was named in celebration of Darwin's 25th birthday. When the Beagle was surveying Australia in 1839, Darwin's friend John Lort Stokes sighted a natural harbour which the ship's captain Wickham named Port Darwin: a nearby settlement was renamed Darwin in 1911, and it became the capital city of Australia's Northern Territory.
More than 120 species and nine genera have been named after Darwin. In one example, the group of tanagers related to those Darwin found in the Galápagos Islands became popularly known as "Darwin's finches" in 1947, fostering inaccurate legends about their significance to his work.
Darwin's work has continued to be celebrated by numerous publications and events. The Linnean Society of London has commemorated Darwin's achievements by the award of the Darwin–Wallace Medal since 1908. Darwin Day has become an annual celebration, and in 2009 worldwide events were arranged for the bicentenary of Darwin's birth and the 150th anniversary of the publication of On the Origin of Species.
Darwin has been commemorated in the UK, with his portrait printed on the reverse of £10 banknotes printed along with a hummingbird and the HMS Beagle, issued by the Bank of England.

Political interpretations

Darwin's fame and popularity led to his name being associated with ideas and movements which at times had only an indirect relation to his writings, and sometimes went directly against his express comments.

Caricature from 1871 Vanity Fair

Eugenics

Darwin was interested by his half-cousin Francis Galton's argument, introduced in 1865, that statistical analysis of heredity showed that moral and mental human traits could be inherited, and principles of animal breeding could apply to humans. In The Descent of Man Darwin noted that aiding the weak to survive and have families could lose the benefits of natural selection, but cautioned that withholding such aid would endanger the instinct of sympathy, "the noblest part of our nature", and factors such as education could be more important. When Galton suggested that publishing research could encourage intermarriage within a "caste" of "those who are naturally gifted", Darwin foresaw practical difficulties, and thought it "the sole feasible, yet I fear utopian, plan of procedure in improving the human race", preferring to simply publicise the importance of inheritance and leave decisions to individuals.
Galton named the field of study "eugenics" in 1883, after Darwin's death, and developed biometrics. Eugenics movements were widespread at a time when Darwin's natural selection was eclipsed by Mendelian genetics, and in some countries compulsory sterilisation laws were imposed, the most famous of which were in Nazi Germany. It has been largely abandoned throughout the world.

Social Darwinism

For more details on this topic, see Social Darwinism.

Taking descriptive ideas as moral and social justification creates the ethical is-ought problem. When Thomas Malthus argued that population growth beyond resources was ordained by God to get humans to work productively and show restraint in getting families, this was used in the 1830s to justify workhouses and laissez-faire economics. Evolution was seen as having social implications, and Herbert Spencer's 1851 book Social Statics based ideas of human freedom and individual liberties on his Lamarckian evolutionary theory.
Darwin's theory of evolution was a matter of explanation. He thought it "absurd to talk of one animal being higher than another" and saw evolution as having no goal, but soon after the Origin was published in 1859, critics derided his description of a struggle for existence as a Malthusian justification for the English industrial capitalism of the time. The term Darwinism was used for the evolutionary ideas of others, including Spencer's "survival of the fittest" as free-market progress, and Ernst Haeckel's racist ideas of human development. Darwin did not share the racism common at that time: a point examined by the philosopher Antony Flew, who is at pains to distance Darwin's attitudes from those later attributed to him. Darwin was strongly against slavery, against "ranking the so-called races of man as distinct species", and against ill-treatment of native people.
Darwin's views on social and political issues reflected his time and social position. He thought men's eminence over women was the outcome of sexual selection, a view disputed by Antoinette Brown Blackwell in The Sexes Throughout Nature. He valued European civilisation and saw colonisation as spreading its benefits, with the sad but inevitable effect of extermination of savage peoples who did not become civilised. Darwin's theories presented this as natural, and were cited to promote policies which went against his humanitarian principles. Writers used natural selection to argue for various, often contradictory, ideologies such as laissez-faire dog-eat dog capitalism, racism, warfare, colonialism and imperialism. However, Darwin's holistic view of nature included "dependence of one being on another"; thus pacifists, socialists, liberal social reformers and anarchists such as Peter Kropotkin stressed the value of co-operation over struggle within a species. Darwin himself insisted that social policy should not simply be guided by concepts of struggle and selection in nature.
The term "Social Darwinism" was used infrequently from around the 1890s, but became popular as a derogatory term in the 1940s when used by Richard Hofstadter to attack the laissez-faire conservatism of those like William Graham Sumner who opposed reform and socialism. Since then it has been used as a term of abuse by those opposed to what they think are the moral consequences of evolution.

Religious

Darwin's family tradition was nonconformist Unitarianism, while his father and grandfather were freethinkers, and his baptism and boarding school were Church of England. When going to Cambridge to become an Anglican clergyman, he did not doubt the literal truth of the Bible. He learnt John Herschel's science which, like William Paley's natural theology, sought explanations in laws of nature rather than miracles and saw adaptation of species as evidence of design. On board the Beagle, Darwin was quite orthodox and would quote the Bible as an authority on morality. He looked for "centres of creation" to explain distribution, and related the antlion found near kangaroos to distinct "periods of Creation".
By his return he was critical of the Bible as history, and wondered why all religions should not be equally valid. In the next few years, while intensively speculating on geology and transmutation of species, he gave much thought to religion and openly discussed this with Emma, whose beliefs also came from intensive study and questioning. The theodicy of Paley and Thomas Malthus vindicated evils such as starvation as a result of a benevolent creator's laws which had an overall good effect. To Darwin, natural selection produced the good of adaptation but removed the need for design, and he could not see the work of an omnipotent deity in all the pain and suffering such as the ichneumon wasp paralysing caterpillars as live food for its eggs. He still viewed organisms as perfectly adapted, and On the Origin of Species reflects theological views. Though he thought of religion as a tribal survival strategy, Darwin still believed that God was the ultimate lawgiver.
Darwin remained close friends with the vicar of Downe, John Innes, and continued to play a leading part in the parish work of the church, but from around 1849 would go for a walk on Sundays while his family attended church. He considered it "absurd to doubt that a man might be an ardent theist and an evolutionist" and, though reticent about his religious views, in 1879 he wrote that "I have never been an atheist in the sense of denying the existence of a God. – I think that generally ... an agnostic would be the most correct description of my state of mind."
The "Lady Hope Story", published in 1915, claimed that Darwin had reverted back to Christianity on his sickbed. The claims were repudiated by Darwin's children and have been dismissed as false by historians. His last words were to his family, telling Emma "I am not the least afraid of death – Remember what a good wife you have been to me – Tell all my children to remember how good they have been to me", then while she rested, he repeatedly told Henrietta and Francis "It's almost worth while to be sick to be nursed by you".

Darwin's children

In 1851 Darwin was devastated when his daughter Annie died. By then his faith in Christianity had dwindled, and he had stopped going to church.
The Darwins had ten children: two died in infancy, and Annie's death at the age of ten had a devastating effect on her parents. Charles was a devoted father and uncommonly attentive to his children. Whenever they fell ill, he feared that they might have inherited weaknesses from inbreeding due to the close family ties he shared with his wife and cousin, Emma Wedgwood. He examined this topic in his writings, contrasting it with the advantages of crossing amongst many organisms. Despite his fears, most of the surviving children and many of their descendants went on to have distinguished careers (see Darwin-Wedgwood family).
Of his surviving children, George, Francis and Horace became Fellows of the Royal Society, distinguished as astronomer, botanist and civil engineer, respectively. His son Leonard went on to be a soldier, politician, economist, eugenicist and mentor of the statistician and evolutionary biologist Ronald Fisher.

Darwin and his eldest son William Erasmus Darwin in 1842.
Darwin's Children
William Erasmus Darwin	(27 December 1839–1914)
Anne Elizabeth Darwin	(2 March 1841–23 April 1851)
Mary Eleanor Darwin	(23 September 1842–16 October 1842)
Henrietta Emma "Etty" Darwin	(25 September 1843–1929)
George Howard Darwin	(9 July 1845–7 December 1912)
Elizabeth "Bessy" Darwin	(8 July 1847–1926)
Francis Darwin	(16 August 1848–19 September 1925)
Leonard Darwin	(15 January 1850–26 March 1943)
Horace Darwin	(13 May 1851–29 September 1928)
Charles Waring Darwin	(6 December 1856–28 June 1858)

Descent of Man, sexual selection, and botany

By 1879, an increasingly famous Darwin had suffered years of illness.

Despite repeated bouts of illness during the last twenty-two years of his life, Darwin's work continued. Having published On the Origin of Species as an abstract of his theory, he pressed on with experiments, research, and writing of his "big book". He covered human descent from earlier animals including evolution of society and of mental abilities, as well as explaining decorative beauty in wildlife and diversifying into innovative plant studies.
Enquiries about insect pollination led in 1861 to novel studies of wild orchids, showing adaptation of their flowers to attract specific moths to each species and ensure cross fertilisation. In 1862 Fertilisation of Orchids gave his first detailed demonstration of the power of natural selection to explain complex ecological relationships, making testable predictions. As his health declined, he lay on his sickbed in a room filled with inventive experiments to trace the movements of climbing plants. Admiring visitors included Ernst Haeckel, a zealous proponent of Darwinismus incorporating Lamarckism and Goethe's idealism. Wallace remained supportive, though he increasingly turned to Spiritualism.
The Variation of Animals and Plants under Domestication of 1868 was the first part of Darwin's planned "big book", and included his unsuccessful hypothesis of pangenesis attempting to explain heredity. It sold briskly at first, despite its size, and was translated into many languages. He wrote most of a second part, on natural selection, but it remained unpublished in his lifetime.

Punch's almanac for 1882, published shortly before Darwin's death, depicts him amidst evolution from chaos to Victorian gentleman with the title Man Is But A Worm.

Lyell had already popularised human prehistory, and Huxley had shown that anatomically humans are apes. With The Descent of Man, and Selection in Relation to Sex published in 1871, Darwin set out evidence from numerous sources that humans are animals, showing continuity of physical and mental attributes, and presented sexual selection to explain impractical animal features such as the peacock's plumage as well as human evolution of culture, differences between sexes, and physical and cultural racial characteristics, while emphasising that humans are all one species. His research using images was expanded in his 1872 book The Expression of the Emotions in Man and Animals, one of the first books to feature printed photographs, which discussed the evolution of human psychology and its continuity with the behaviour of animals. Both books proved very popular, and Darwin was impressed by the general assent with which his views had been received, remarking that "everybody is talking about it without being shocked." His conclusion was "that man with all his noble qualities, with sympathy which feels for the most debased, with benevolence which extends not only to other men but to the humblest living creature, with his god-like intellect which has penetrated into the movements and constitution of the solar system–with all these exalted powers–Man still bears in his bodily frame the indelible stamp of his lowly origin."
His evolution-related experiments and investigations led to books on Insectivorous Plants, The Effects of Cross and Self Fertilisation in the Vegetable Kingdom, different forms of flowers on plants of the same species, and The Power of Movement in Plants. In his last book he returned to The Formation of Vegetable Mould through the Action of Worms.
He died at Down House on 19 April 1882. He had expected to be buried in St Mary's churchyard at Downe, but at the request of Darwin's colleagues, William Spottiswoode (President of the Royal Society) arranged for Darwin to be given a state funeral and buried in Westminster Abbey, close to John Herschel and Isaac Newton. Only five non-royal personages were granted that honour of a UK state funeral during the 19th century.
Darwin was perceived as a national hero who had changed thinking, and scientists now accepted evolution as descent with modification, but few agreed with him that "natural selection has been the main but not the exclusive means of modification". In "the eclipse of Darwinism" most favoured alternative evolutionary mechanisms, but these proved untenable, and the development of the modern evolutionary synthesis with population genetics and Mendelian genetics from the 1930s to the 1950s brought a broad scientific consensus that natural selection was the basic mechanism of evolution. Research and debate has continued within this frame of reference.

Responses to the publication

During the Darwin family's 1868 holiday in her Isle of Wight cottage, Julia Margaret Cameron took portraits showing the bushy beard Darwin had grown by 1866.

An 1871 caricature following publication of The Descent of Man was typical of many showing Darwin with an ape body, identifying him in popular culture as the leading author of evolutionary theory.

The book aroused international interest, with less controversy than had greeted the popular Vestiges of Creation. Though Darwin's illness kept him away from the public debates, he eagerly scrutinised the scientific response, commenting on press cuttings, reviews, articles, satires and caricatures, and corresponded on it with colleagues worldwide. Darwin had only said "Light will be thrown on the origin of man", but the first review claimed it made a creed of the "men from monkeys" idea from Vestiges. Amongst early favourable responses, Huxley's reviews swiped at Richard Owen, leader of the scientific establishment Huxley was trying to overthrow. In April, Owen's review attacked Darwin's friends and condescendingly dismissed his ideas, angering Darwin,but Owen and others began to promote ideas of supernaturally guided evolution.
The Church of England's response was mixed. Darwin's old Cambridge tutors Sedgwick and Henslow dismissed the ideas, but liberal clergymen interpreted natural selection as an instrument of God's design, with the cleric Charles Kingsley seeing it as "just as noble a conception of Deity". In 1860, the publication of Essays and Reviews by seven liberal Anglican theologians diverted clerical attention from Darwin, with its ideas including higher criticism attacked by church authorities as heresy. In it, Baden Powell argued that miracles broke God's laws, so belief in them was atheistic, and praised "Mr Darwin's masterly volume [supporting] the grand principle of the self-evolving powers of nature". Asa Gray discussed teleology with Darwin, who imported and distributed Gray's pamphlet on theistic evolution, Natural Selection is not inconsistent with Natural Theology. The most famous confrontation was at the public 1860 Oxford evolution debate during a meeting of the British Association for the Advancement of Science, where the Bishop of Oxford Samuel Wilberforce, though not opposed to transmutation of species, argued against Darwin's explanation and human descent from apes. Joseph Hooker argued strongly for Darwin, and Thomas Huxley's legendary retort, that he would rather be descended from an ape than a man who misused his gifts, came to symbolise a triumph of science over religion.
Even Darwin's close friends Gray, Hooker, Huxley and Lyell still expressed various reservations but gave strong support, as did many others, particularly younger naturalists. Gray and Lyell sought reconciliation with faith, while Huxley portrayed a polarisation between religion and science. He campaigned pugnaciously against the authority of the clergy in education, aiming to overturn the dominance of clergymen and aristocratic amateurs under Owen in favour of a new generation of professional scientists. Owen's claim that brain anatomy proved humans to be a separate biological order from apes was shown to be false by Huxley in a long running dispute parodied by Kingsley as the "Great Hippocampus Question", and discredited Owen.
Darwinism became a movement covering a wide range of evolutionary ideas. In 1863 Lyell's Geological Evidences of the Antiquity of Man popularised prehistory, though his caution on evolution disappointed Darwin. Weeks later Huxley's Evidence as to Man's Place in Nature showed that anatomically, humans are apes, then The Naturalist on the River Amazons by Henry Walter Bates provided empirical evidence of natural selection. Lobbying brought Darwin Britain's highest scientific honour, the Royal Society's Copley Medal, awarded on 3 November 1864. That day, Huxley held the first meeting of what became the influential X Club devoted to "science, pure and free, untrammelled by religious dogmas". By the end of the decade most scientists agreed that evolution occurred, but only a minority supported Darwin's view that the chief mechanism was natural selection.
The Origin of Species was translated into many languages, becoming a staple scientific text attracting thoughtful attention from all walks of life, including the "working men" who flocked to Huxley's lectures.Darwin's theory also resonated with various movements at the time^.
 and became a key fixture of popular culture. Cartoonists parodied animal ancestry in an old tradition of showing humans with animal traits, and in Britain these droll images served to popularise Darwin's theory in an unthreatening way. While ill in 1862 Darwin began growing a beard, and when he reappeared in public in 1866 caricatures of him as an ape helped to identify all forms of evolutionism with Darwinism.

Publication of the theory of natural selection

Darwin was forced into swift publication of his 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". His theory is simply stated in the introduction:

As many more individuals of each species are born than can possibly survive; and as, consequently, there is a frequently recurring struggle for existence, it follows that any being, if it vary however slightly in any manner profitable to itself, under the complex and sometimes varying conditions of life, will have a better chance of surviving, and thus be naturally selected. From the strong principle of inheritance, any selected variety will tend to propagate its new and modified form.

He put a strong case for common descent, but avoided the then controversial term "evolution", and at the end of the book concluded that:
There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved

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."

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".

Overwork, illness, and marriage

Overwork, illness, and marriage

See also: Charles Darwin's health

While developing this intensive study of transmutation, Darwin became mired in more work. Still rewriting his Journal, he took on editing and publishing the expert reports on his collections, and with Henslow's help obtained a Treasury grant of £1,000 to sponsor this multi-volume Zoology of the Voyage of H.M.S. Beagle, a sum equivalent to about £75,000 in 2009. He stretched the funding to include his planned books on geology, and agreed unrealistic dates with the publisher. As the Victorian era began, Darwin pressed on with writing his Journal, and in August 1837 began correcting printer's proofs.
Darwin's health suffered from the pressure. On 20 September he had "an uncomfortable palpitation of the heart", so his doctors urged him to "knock off all work" and live in the country for a few weeks. After visiting Shrewsbury he joined his Wedgwood relatives at Maer Hall, Staffordshire, but found them too eager for tales of his travels to give him much rest. His charming, intelligent, and cultured cousin Emma Wedgwood, nine months older than Darwin, was nursing his invalid aunt. His uncle Jos pointed out an area of ground where cinders had disappeared under loam and suggested that this might have been the work of earthworms, inspiring "a new & important theory" on their role in soil formation which Darwin presented at the Geological Society on 1 November.
William Whewell pushed Darwin to take on the duties of Secretary of the Geological Society. After initially declining the work, he accepted the post in March 1838. Despite the grind of writing and editing the Beagle reports, Darwin made remarkable progress on transmutation, taking every opportunity to question expert naturalists and, unconventionally, people with practical experience such as farmers and pigeon fanciers.Over time his research drew on information from his relatives and children, the family butler, neighbours, colonists and former shipmates.He included mankind in his speculations from the outset, and on seeing an orangutan in the zoo on 28 March 1838 noted its child-like behaviour.
The strain took a toll, and by June he was being laid up for days on end with stomach problems, headaches and heart symptoms. For the rest of his life, he was repeatedly incapacitated with episodes of stomach pains, vomiting, severe boils, palpitations, trembling and other symptoms, particularly during times of stress such as attending meetings or making social visits. The cause of Darwin's illness remained unknown, and attempts at treatment had little success.
On 23 June he took a break and went "geologising" in Scotland. He visited Glen Roy in glorious weather to see the parallel "roads" cut into the hillsides at three heights. He later published his view that these were marine raised beaches, but then had to accept that they were shorelines of a proglacial lake.
Fully recuperated, he returned to Shrewsbury in July. Used to jotting down daily notes on animal breeding, he scrawled rambling thoughts about career and prospects on two scraps of paper, one with columns headed "Marry" and "Not Marry". Advantages included "constant companion and a friend in old age ... better than a dog anyhow", against points such as "less money for books" and "terrible loss of time."Having decided in favour, he discussed it with his father, then went to visit Emma on 29 July. He did not get around to proposing, but against his father's advice he mentioned his ideas on transmutation.
Continuing his research in London, Darwin's wide reading now included the sixth edition of Malthus's An Essay on the Principle of Population

In October 1838, that is, fifteen months after I had begun my systematic enquiry, I happened to read for amusement Malthus on Population, and being well prepared to appreciate the struggle for existence which everywhere goes on from long-continued observation of the habits of animals and plants, it at once struck me that under these circumstances favourable variations would tend to be preserved, and unfavourable ones to be destroyed. The result of this would be the formation of new species. Here, then, I had at last got a theory by which to work...

Malthus asserted that unless human population is kept in check, it increases in a geometrical progression and soon exceeds food supply in what is known as a Malthusian catastrophe. Darwin was well prepared to see at once that this also applied to de Candolle's "warring of the species" of plants and the struggle for existence among wildlife, explaining how numbers of a species kept roughly stable. As species always breed beyond available resources, favourable variations would make organisms better at surviving and passing the variations on to their offspring, while unfavourable variations would be lost. This would result in the formation of new species. On 28 September 1838 he noted this insight, describing it as a kind of wedging, forcing adapted structures into gaps in the economy of nature as weaker structures were thrust out. By mid December he saw a similarity between farmers picking the best breeding stock and a Malthusian Nature selecting from chance variants so that "every part of newly acquired structure is fully practical and perfected",thinking this comparison "a beautiful part of my theory".

Darwin chose to marry his cousin, Emma Wedgwood.

On 11 November, he returned to Maer and proposed to Emma, once more telling her his ideas. She accepted, then in exchanges of loving letters she showed how she valued his openness in sharing their differences, also expressing her strong Unitarian beliefs and concerns that his honest doubts might separate them in the afterlife. While he was house-hunting in London, bouts of illness continued and Emma wrote urging him to get some rest, almost prophetically remarking "So don't be ill any more my dear Charley till I can be with you to nurse you." He found what they called "Macaw Cottage" (because of its gaudy interiors) in Gower Street, then moved his "museum" in over Christmas. On 24 January 1839 Darwin was elected a Fellow of the Royal Society.
On 29 January Darwin and Emma Wedgwood were married at Maer in an Anglican ceremony arranged to suit the Unitarians, then immediately caught the train to London and their new home.

Inception of Darwin's evolutionary theory

While still a young man, Charles Darwin joined the scientific elite

When the Beagle reached Falmouth, Cornwall, 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 other gigantic extinct ground sloths as well as the Megatherium, 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 actually 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. 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. Transmutation was anathema to Anglicans defending social order, but reputable scientists openly discussed the subject and there was wide interest in John Herschel's letter praising Lyell's approach as a way to find a natural cause of the origin of new species.
Gould met Darwin and told him that the Galápagos mockingbirds from different islands were separate species, not just varieties, and what Darwin had thought was a "wren" was also in the finch group. 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.

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 which resembled 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.