KEY WORKS
Charles Robert Darwin was an English naturalist who showed that all species of life have descended over time from common ancestors, and proposed the scientific theory that this branching pattern of evolution resulted from a process that he called natural selection. He published his theory with compelling evidence for evolution in his 1859 book On the Origin of Species.The scientific community and much of the general public came to accept evolution as a fact 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 medical education at the University of Edinburgh; instead, he helped to investigate marine invertebrates. Studies at the University of Cambridge encouraged his 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.
Charles Robert Darwin was born in Shrewsbury, Shropshire, England on 12 February 1809 at his family home, the Mount.He was the fifth of six children of wealthy society doctor and financier Robert Darwin, and Susannah Darwin (née Wedgwood). He was the grandson of Erasmus Darwin on his father's side, and of Josiah Wedgwood on his mother's side. Both families were largely Unitarian, though the Wedgwoods were adopting Anglicanism. Robert Darwin, himself quietly a freethinker, had baby Charles baptised in the Anglican Church, but Charles and his siblings attended the Unitarian chapel with their mother. The eight year old Charles already had a taste for natural history and collecting when he joined the day school run by its preacher in 1817. That July, his mother died. From September 1818, he joined his older brother Erasmus attending the nearby Anglican Shrewsbury School as a boarder.
In Darwin's second year he joined the Plinian Society, a student natural history group whose debates strayed into radical materialism. He assisted Robert Edmund Grant's investigations of the anatomy and life cycle of marine invertebrates in the Firth of Forth, and in March 1827 presented at the Plinian his own discovery that black spores found in oyster shells were the eggs of a skate leech. One day, Grant praised Lamarck's evolutionary ideas. Darwin was astonished, but had recently read the similar ideas of his grandfather Erasmus and remained indifferent.Darwin was rather bored by Robert Jameson's natural history course which covered geology including the debate between Neptunism and Plutonism. He learned classification of plants, and assisted with work on the collections of the University Museum, one of the largest museums in Europe at the time.
This neglect of medical studies annoyed his father, who shrewdly sent him to Christ's College, Cambridge, for a Bachelor of Arts degree as the first step towards becoming an Anglican parson.[20] Darwin began there in January 1828, but preferred riding and shooting to studying. His cousin William Darwin Fox introduced him to the popular craze for beetle collecting which he pursued zealously, getting some of his finds published in Stevens' Illustrations of British entomology. He became a close friend and follower of botany professor John Stevens Henslow and met other leading naturalists who saw scientific work as religious natural theology, becoming known to these dons as "the man who walks with Henslow". When exams drew near, Darwin focused on his studies and was delighted by the language and logic of William Paley's Evidences of Christianity. In his final examination in January 1831 Darwin did well, coming tenth out of a pass list of 178.
Darwin had to stay at Cambridge until June. He studied Paley's Natural Theology which made an argument for divine design in nature, explaining adaptation as God acting through laws of nature. He read John Herschel's new book which described the highest aim of natural philosophy as understanding such laws through inductive reasoning based on observation, and Alexander von Humboldt's Personal Narrative of scientific travels. Inspired with "a burning zeal" to contribute, Darwin planned to visit Tenerife with some classmates after graduation to study natural history in the tropics. In preparation, he joined Adam Sedgwick's geology course, then went with him in the summer for a fortnight to map strata in Wales.After a week with student friends at Barmouth, he returned home to find a letter from Henslow proposing Darwin as a suitable (if unfinished) gentleman naturalist for a self-funded place with captain Robert FitzRoy, more as a companion than a mere collector, on HMS Beagle which was to leave in four weeks on an expedition to chart the coastline of South America.His father objected to the planned two-year voyage, regarding it as a waste of time, but was persuaded by his brother-in-law, Josiah Wedgwood, to agree to his son's participation.
Journey of the Beagle
Beginning on the 27th of December, 1831, the voyage lasted almost five years and, as FitzRoy had intended, Darwin spent most of that time on land investigating geology and making natural history collections, while the Beagle surveyed and charted coasts.He kept careful notes of his observations and theoretical speculations, and at intervals during the voyage his specimens were sent to Cambridge together with letters including a copy of his journal for his family.He had some expertise in geology, beetle collecting and dissecting marine invertebrates, but in all other areas was a novice and ably collected specimens for expert appraisal.Despite repeatedly suffering badly from seasickness while at sea, most of his zoology notes are about marine invertebrates, starting with plankton collected in a calm spell.
On their first stop ashore at St. Jago, Darwin found that a white band high in the volcanic rock cliffs included seashells. FitzRoy had given him the first volume of Charles Lyell's Principles of Geology which set out uniformitarian concepts of land slowly rising or falling over immense periods,and Darwin saw things Lyell's way, theorising and thinking of writing a book on geology. In Brazil, Darwin was delighted by the tropical forest,but detested the sight of slavery
At Punta Alta in Patagonia he made a major find of fossil bones of huge extinct mammals in cliffs beside modern seashells, indicating recent extinction with no signs of change in climate or catastrophe. He identified the little known Megatherium by a tooth and its association with bony armour which had at first seemed to him like a giant version of the armour on local armadillos. The finds brought great interest when they reached England.On rides with gauchos into the interior to explore geology and collect more fossils he gained social, political and anthropological insights into both native and colonial people at a time of revolution, and learnt that two types of rhea had separate but overlapping territories.Further south he saw stepped plains of shingle and seashells as raised beaches showing a series of elevations. He read Lyell's second volume and accepted its view of "centres of creation" of species, but his discoveries and theorising challenged Lyell's ideas of smooth continuity and of extinction of species.
On the geologically new Galápagos Islands Darwin looked for evidence attaching wildlife to an older "centre of creation", and found mockingbirds allied to those in Chile but differing from island to island. He heard that slight variations in the shape of tortoise shells showed which island they came from, but failed to collect them, even after eating tortoises taken on board as food. In Australia, the marsupial rat-kangaroo and the platypus seemed so unusual that Darwin thought it was almost as though two distinct Creators had been at work.He found the Aborigines "good-humoured & pleasant", and noted their depletion by European settlement.
The Beagle investigated how the atolls of the Cocos (Keeling) Islands had formed, and the survey supported Darwin's theorising.FitzRoy began writing the official Narrative of the Beagle voyages, and after reading Darwin's diary he proposed incorporating it into the account. Darwin's Journal was eventually rewritten as a separate third volume, on natural history.
In Cape Town Darwin and FitzRoy met John Herschel, who had recently written to Lyell praising his uniformitarianism as opening bold speculation on "that mystery of mysteries, the replacement of extinct species by others" as "a natural in contradistinction to a miraculous process".When organising his notes as the ship sailed home, Darwin wrote that if his growing suspicions about the mockingbirds, the tortoises and the Falkland Islands Fox were correct, "such facts undermine the stability of Species", then cautiously added "would" before "undermine".He later wrote that such facts "seemed to me to throw some light on the origin of species".
Inception of Darwin's evolutionary theory
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. 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.
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.
Overwork, illness, and marriage
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 2008. 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.
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.
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
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".
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.
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."
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.
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.
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.
Responses to the publication
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.
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.
Descent of Man, sexual selection, and botany
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.
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 Power of Movement in 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.
Copyright(c) 2007
- 2012. All rights reserved.
|
Born |
12 February 1809(1809-02-12) Mount House, Shrewsbury, Shropshire, England |
|
Died |
19 April 1882 (aged 73) Down House, Downe, Kent, England |
|
Residence |
England |
|
Citizenship |
|
|
Ethnicity |
White British |
|
Field |
Naturalist |
|
Institution |
Geological Society of London |
|
Works |
The
Voyage of the Beagle On The Origin of Species Natural selection |