Charles Robert Darwin (12 February 1809 – 19 April 1882) was an eminent English naturalist[I] who achieved lasting fame by convincing the scientific community that species develop over time from a common origin. His theories explaining this phenomenon through natural and sexual selection are central to the modern understanding of evolution as the unifying theory of the life sciences, essential in biology and important in other disciplines such as anthropology, psychology and philosophy.[1]
Darwin developed his interest in natural history while studying first medicine, then theology, at university.[2] His five-year voyage on the Beagle established him as a geologist whose observations and theorising supported Charles Lyell's uniformitarian ideas, and the subsequent 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, he investigated the transmutation of species and conceived his theory of natural selection in 1838. He had seen others attacked for such heretical ideas and confided only in his closest friends while carrying out extensive research to meet anticipated objections.[3] However, in 1858, Alfred Russel Wallace sent him an essay describing a similar theory, forcing early joint publication of both of their theories.[4]
His 1859 book, On the Origin of Species, established evolution by common descent as the dominant scientific explanation of diversification in nature. Human origins and features without obvious utility such as beautiful bird plumage were examined 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.[5]
In recognition of Darwin's pre-eminence, he was buried in Westminster Abbey, close to John Herschel and Isaac Newton.[6]
[edit] Journey on the Beagle
As
HMS Beagle surveyed the coasts of
South America, Darwin began to theorise about the wonders of nature around him.
The Beagle survey took five years, two-thirds of which Darwin spent on land. He carefully noted a rich variety of geological features, fossils and living organisms, and methodically collected an enormous number of specimens, many of them new to science.[23] At intervals during the voyage specimens were sent to Cambridge together with letters about his findings, and established his reputation as a naturalist. His extensive detailed notes showed his gift for theorising and formed the basis for his later work. The journal he originally wrote for his family, published as The Voyage of the Beagle, summarises his findings and provides social, political and anthropological insights into the wide range of people he met, both native and colonial.[24]
While on board the ship, Darwin suffered badly from seasickness.[25] In October 1833, he caught a fever in Argentina, and in July 1834, while returning from the Andes down to Valparaíso, he fell ill and spent a month in bed.[26]
Before they set out, Fitzroy gave Darwin volume one of Charles Lyell's Principles of Geology, which explained landforms as the outcome of gradual processes over huge periods of time.[II] On their first stop ashore at St Jago Darwin found that a white band high in the volcanic rock cliffs consisted of baked coral fragments and shells. This matched Lyell's concept of land slowly rising or falling, giving Darwin a new insight into the geological history of the island which inspired him to think of writing a book on geology.[27] He went on to make many more discoveries. some of them particularly dramatic.[23] He saw stepped plains of shingle and seashells in Patagonia as raised beaches, and after experiencing an earthquake in Chile saw mussel-beds stranded above high tide showing that the land had just been raised. High in the Andes he saw fossil trees that had grown on a sand beach, with seashells nearby. He theorised that coral atolls form on sinking volcanic mountains, and confirmed this when the Beagle surveyed the Cocos (Keeling) Islands.[28]
In South America, Darwin found and excavated rare fossils of gigantic extinct mammals, some in strata which showed no signs of catastrophe or change in climate. A huge skull seemed to him to be related to the African rhinoceros. At first, he thought that fragments of bony armour came from a gigantic armadillo like the small creatures common in the area, but was then misled by Bory de Saint-Vincent's Dictionnaire classique into thinking they belonged to the megatherium fossils he found nearby.[29] He was sent Lyell's second volume which argued against evolutionism and explained species distribution by "centres of creation". Darwin puzzled over all he saw and his ideas went beyond Lyell.[30] In Argentina, he found that two types of rhea had separate but overlapping territories. On the Galápagos Islands, he collected mockingbirds and noted that they were different depending on which island they came from. He also heard that local Spaniards could tell from their appearance which island tortoises originated on, but thought the creatures had been imported by buccaneers.[31] 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.[32] In Cape Town he and FitzRoy met John Herschel, who had recently written to Lyell about that "mystery of mysteries", the origin of species. When organising his notes on the return journey, Darwin wrote that if his growing suspicions about the mockingbirds and tortoises were correct, "such facts undermine the stability of Species", then cautiously added "would" before "undermine".[33] He later wrote that such facts "seemed to me to throw some light on the origin of species".[34]
Three natives who had been taken from Tierra del Fuego on the Beagle's previous voyage were taken back there to become missionaries. They had become "civilised" in England over the previous two years, yet their relatives appeared to Darwin to be "miserable, degraded savages".[35] A year on, the mission had been abandoned and only Jemmy Button spoke with them to say he preferred his harsh previous way of life and did not want to return to England. As a result of this experience, Darwin came to think that humans were not as far removed from animals as his friends believed, and saw differences as relating to cultural advances towards civilisation rather than being racial. He detested the slavery he saw elsewhere in South America, and was saddened by the effects of European settlement on aborigines in New Zealand and Australia.[36]
Captain FitzRoy was committed to writing the official Narrative of the Beagle voyages, and near the end of the voyage, he read Darwin's diary and asked him to rewrite this Journal to provide the third volume, on natural history.[37]
[edit] Growing reputation and inception of theory
While still a young man, Charles Darwin joined the scientific élite.
While Darwin was still on the voyage, Henslow fostered his former pupil's reputation by giving selected naturalists access to the fossil specimens and a pamphlet of Darwin's geological letters.[38] When the Beagle returned on 2 October 1836, Darwin was a celebrity in scientific circles. After visiting his home in Shrewsbury and seeing relatives, Darwin hurried to Cambridge to see Henslow, who advised on finding naturalists available to describe and 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.[39]
An eager Charles Lyell 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 at his disposal to work on Darwin's fossil bones. Owen's surprising results included gigantic sloths, a hippopotamus-like skull from the extinct rodent toxodon, and armour fragments from a huge extinct armadillo (glyptodon), as Darwin had initially surmised.[40] The fossil creatures were unrelated to African animals, but closely related to living species in South America.[41]
In mid December, Darwin moved to Cambridge to organise work on his collections and rewrite his Journal.[42] 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 revealed that the Galapagos birds that Darwin had thought a mixture of blackbirds, "gross-beaks" and finches, were, in fact, twelve separate species of finches. On 17 February 1837, Darwin was elected to the Council of the Geographical Society, and in his presidential address, Lyell presented Owen's findings on Darwin's fossils, stressing geographical continuity of species as supporting his uniformitarian ideas.[43]
Darwin's first sketch of an evolutionary tree from his First Notebook on Transmutation of Species (1837)
On 6 March 1837, Darwin moved to London to be close to this work, and joined the social whirl around scientists and savants such as Babbage, who thought that God preordained life by natural laws rather than ad hoc miraculous creations. Darwin lived near his freethinking brother Erasmus, who was part of this Whig circle and whose close friend the writer Harriet Martineau promoted the ideas of Thomas Malthus underlying the Whig "Poor Law reforms" aimed at discouraging the poor from breeding beyond available food supplies. John Herschel's question on the origin of species was widely discussed. Medical men including Dr. Gully even joined Grant in endorsing transmutation of species, but to Darwin's scientist friends such radical heresy attacked the divine basis of the social order already under threat from recession and riots.[44]
Gould now revealed that the Galapagos mockingbirds from different islands were separate species, not just varieties, and the "wrens" were yet another species of finches. Darwin had not kept track of which islands the finch specimens were from, but found information from the notes of others on the Beagle, including FitzRoy, who had more carefully recorded their own collections. The zoologist Thomas Bell showed that the Galápagos tortoises were native to the islands. By mid March, Darwin was convinced that creatures arriving in the islands had become altered in some way to form new species on the different islands, and investigated transmutation while noting his speculations in his "Red Notebook" which he had begun on the Beagle. In mid-July, he began his secret "B" notebook on transmutation, and on page 36 wrote "I think" above his first sketch of an evolutionary tree.[45]
[edit] Preparing the theory of natural selection for publication
Darwin had found the basis of his theory of natural selection, but was aware of how much work was needed to make it credible to his fiercely critical scientific colleagues. As Secretary of the Geological Society at its meeting on 19 December 1838, he saw Owen and Buckland display their hatred of evolution when destroying the reputation of his old Lamarckian teacher Grant.[63] Work on his Beagle findings continued, and as well as consulting animal husbanders he carried out extensive experiments with plants, trying to find evidence answering all the arguments he anticipated when his theory was made public.[64] When FitzRoy's Narrative was published in May 1839, Darwin's Journal and Remarks (The Voyage of the Beagle) as the third volume was such a success that later that year it was published on its own.[65]
Early in 1842, Darwin sent a letter about his ideas to Lyell, who was dismayed that his ally now denied "seeing a beginning to each crop of species". Darwin then wrote a "pencil sketch" of his theory.[66] To escape the pressures of London, the family moved to rural Down House in November.[67] On 11 January 1844 Darwin wrote to his botanist friend Joseph Dalton Hooker about his theory, saying it was like confessing "a murder", but to his relief Hooker thought that "there might have been a gradual change of species" and expressed interest in Darwin's explanation. By July Darwin had expanded his "sketch" into a 230-page "Essay".[68] His fears that his ideas would be dismissed as Lamarckian Radicalism were reawakened by controversy over the anonymous publication in October of Vestiges of the Natural History of Creation which was severely attacked by establishment scientists. However, the book was a best-seller and widened middle-class interest in transmutation, paving the way for Darwin as well as reminding him of the need to answer all difficulties before making his theory public. Darwin completed his third geological book in 1846, and embarked on a huge study of barnacles with the assistance of Hooker. 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.[69]
In an attempt to improve his chronic ill health, Darwin went to a spa in Malvern in 1849. To his surprise, he found that two months of water treatment helped.[70] Then his treasured daughter Annie fell ill, reawakening his fears that his illness might be hereditary. After a long series of crises, she died and Darwin lost all faith in a beneficent God.[71]
Darwin's eight years of work on barnacles (Cirripedia) found "homologies" that supported his theory by showing that slightly changed body parts could serve different functions to meet new conditions.[72] In 1853 it earned him the Royal Society's Royal Medal, and it made his reputation as a biologist.[73] In 1854 he resumed work on his theory of species, 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".[74]
[edit] Publication of theory
By the Spring of 1856, Darwin was investigating how species spread. Hooker increasingly doubted the traditional view that species were fixed, but their new ally Huxley was firmly against evolution. Lyell was intrigued by Darwin's speculations without realising their extent, and when he read a paper by 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. He was repeatedly held up by finding answers to difficult questions such as how seeds could travel across seawater, and 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. In December 1857, 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."[75]
Darwin's book was half way when, on 18 June 1858, he received a paper from Wallace describing natural selection. Though shocked that he had been "forestalled", Darwin sent it on to Lyell, as requested, and, though Wallace had not asked for publication, offered to 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 agreed 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 fever and he was too distraught to attend.[76]
There was little immediate attention to this announcement of the theory; the president of the Linnean left the meeting lamenting that the year had not been marked by any great discoveries.[77] Later, Darwin could only recall one review; Professor Haughton of Dublin claimed that "all that was new in them was false, and what was true was old."[78] 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.[79]
On the Origin of Species by Means of Natural Selection, or The Preservation of Favoured Races in the Struggle for Life (usually abbreviated to 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.[80] In the book, Darwin set out "one long argument" of facts, inferences and consideration of anticipated objections.[81] His only allusion to human evolution was the understatement that "light will be thrown on the origin of man and his history".[82] He avoided the then controversial term "evolution", but at the end of the book concluded that "endless forms most beautiful and most wonderful have been, and are being, evolved."[83] 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.[84]
[edit] Political interpretations
A classic image of Darwin in 1880, still researching and producing numerous books.
Darwin's theories and writings, combined with Gregor Mendel's genetics, (the "modern synthesis") form the basis of all modern biology.[123] However, 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.
[edit] Eugenics
Following Darwin's publication of the Origin, his cousin, Francis Galton, applied the concepts to human society, starting in 1865 with ideas to promote "hereditary improvement" which he elaborated at length in 1869.[124] In The Descent of Man Darwin agreed that Galton had demonstrated the probability that "talent" and "genius" in humans was inherited, but dismissed the social changes Galton proposed as too utopian.[125] Neither Galton nor Darwin supported government intervention and instead believed that, at most, heredity should be taken into consideration by people seeking potential mates.[126] In 1883, after Darwin's death, Galton began calling his social philosophy Eugenics.[127] In the twentieth century, eugenics movements gained popularity in a number of countries and became associated with reproduction control programmes such as compulsory sterilisation laws,[128] then were stigmatised after their usage in the rhetoric of Nazi Germany in its goals of genetic "purity".[V]
[edit] Social Darwinism
The ideas of Thomas Malthus and Herbert Spencer which applied ideas of evolution and "survival of the fittest" to societies, nations and businesses became popular in the late 19th and early 20th century, and were used to defend various, sometimes contradictory, ideological perspectives including laissez-faire economics,[129]colonialism,[130]racism and imperialism.[130] The term, "Social Darwinism", originated around the 1890s, but became popular as a derogatory term in the 1940s with Richard Hofstadter's critique of laissez-faire conservatism.[131] The concepts predate Darwin's publication of the Origin in 1859:[130][132] Malthus died in 1834[133] and Spencer published his books on economics in 1851 and on evolution in 1855.[134] Darwin himself insisted that social policy should not simply be guided by concepts of struggle and selection in nature,[135] and that sympathy should be extended to all races and nations.[136][VI]
The Origin of Species
British naturalist Charles Darwin's book, The Origin of Species, is one of the pivotal works in scientific literature and arguably the pre-eminent work in biology.[1] First published in 1859, the full title is On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life. It introduced the theory that populations evolve over the course of generations through a process of natural selection. It was controversial because it contradicted religious beliefs and the doctrine of "created kinds", which underlay the then widely accepted theories of biology. Darwin's book was the culmination of evidence he had accumulated on the voyage of the Beagle in the 1830s and added to through continuing investigations and experiments since his return.[2]
The book is readable even for the non-specialist and attracted widespread interest on publication. The book was controversial, and generated much discussion on scientific, philosophical, and religious grounds. The scientific theory of evolution has itself evolved since Darwin first presented it, but evolution remains the best and most widely accepted scientific model of the origin of species. Even so, seemingly irreconciable incompatibilities between literal interpretations of various religious accounts and Darwin's theory remain, and are still the subject of the vigorous creation-evolution controversy.
[edit] Theory in a nutshell
Darwin's theory is based on key observations and inferences drawn from them:[3]
- Species have great fertility. They make more offspring than can grow to adulthood.
- Populations remain roughly the same size, with modest fluctuations.
- Food resources are limited, but are relatively stable over time.
- An implicit struggle for survival ensues.
- In sexually reproducing species, generally no two individuals are identical.
- Some of these variations directly impact the ability of an individual to survive in a given environment.
- Much of this variation is inheritable.
- Individuals less suited to the environment are less likely to survive and less likely to reproduce, while individuals more suited to the environment are more likely to survive and more likely to reproduce.
- The individuals that survive are most likely to leave their inheritable traits to future generations.
- This slowly effected process results in populations that adapt to the environment over time, and ultimately, after interminable generations, the creations of new varieties, and ultimately, new species.
[edit] Background
The idea of biological evolution was around long before Darwin published The Origin, and was set out in Classical times by the Greek and Roman atomists, notably Lucretius. However, Christian thought in Medieval Europe involved complete faith in the ancient Biblical teachings of creation according to Genesis. Its concepts including "Created kinds" were interpreted by the priesthood as theology, then the Protestant Reformation widened access to the Bible and brought more literal interpretations. Natural history exploring the wonders of God's works made many discoveries and naturalists such as Carolus Linnaeus categorised an enormous number of species. A new belief developed that the original pair of every species had been brought into existence by God not so long ago. By the time of Darwin's birth in 1809, it was widely believed in England that both the natural world and the hierarchical social order were held stable, fixed by God's will, with nothing happening purely naturally and spontaneously.[4]
The idea that fossils were the remains of extinct species, first put forward by Robert Hooke in the mid seventeenth century, gradually gained acceptance and several competing theories of geology were put forward, notably James Hutton's uniformitarian theory of 1785 which envisioned gradual change over aeons of time. Some individuals put forward evolutionary concepts. By 1796 Charles Darwin's grandfather Erasmus Darwin had proposed ideas of common descent with organisms "acquiring new parts" in response to stimuli then passing these changes to their offspring. In 1809 Jean-Baptiste Lamarck developed a similar theory, with "needed" traits being acquired through use then passed on. At this time the word evolution (from the Latin word "evolutio", meaning "unroll like a scroll") was used to refer to an orderly sequence of events, particularly one in which the outcome was somehow contained within it from the start, so Lamarck avoided using this word for his concept in which traits were acquired during an organism's life, and the term transmutation came into use.
Such ideas were seen in Britain as attacking the social order, already threatened by the aftermath of the American and French Revolutions.[5] In England, natural history was dominated by the universities which trained clergy for the Church of England in William Paley's natural theology which sought evidence of beneficial "design" by a Creator. British naturalists adopted Georges Cuvier's explanation of the fossil record by catastrophism, the concept that animals and plants were periodically annihilated as a result of natural catastrophes and that their places were taken by new species created ex nihilo (out of nothing), modifying it to support the biblical account of Noah's flood.[6] However Lamarck's ideas were taken up by Radicals who wanted to overturn the establishment and extend the vote to the lower classes.[7]
[edit] Inception of Darwin's theory
Charles Darwin's education at the University of Edinburgh gave him direct involvement in Robert Edmund Grant's evolutionist developments of the ideas of Erasmus Darwin and Jean-Baptiste Lamarck. Then at Cambridge University his theology studies convinced him of William Paley's argument of "design" by a Creator while his interest in natural history was increased by the botanist John Stevens Henslow and the geologist Adam Sedgwick, both of whom believed strongly in divine creation. During the voyage of the Beagle Charles Darwin became convinced by Charles Lyell's uniformitarianism, and puzzled over discrepancies between Lyell's uniformitarian idea that each species had its "centre of creation" and the evidence he saw. On his return Richard Owen showed that fossils Darwin had found were of extinct species related to current species in the same locality, and John Gould startlingly revealed that completely different birds from the Galápagos Islands were species of finches distinct to each island.
By early 1837 Darwin was speculating on transmutation in a series of secret notebooks. He investigated the breeding of domestic animals, consulting William Yarrell and reading a pamphlet by Yarrell's friend Sir John Sebright which commented that "A severe winter, or a scarcity of food, by destroying the weak and the unhealthy, has all the good effects of the most skilful selection." At the zoo in 1838 he had his first sight of an ape, and the orang-utan's antics impressed him as being "just like a naughty child" which from his experience of the natives of Tierra del Fuego made him think that there was little gulf between man and animals despite theological doctrines that only mankind possessed a soul.
In late September 1838 he began reading the 6th edition of Malthus's Essay on the Principle of Population which reminded him of Malthus's statistical proof that human populations breed beyond their means and compete to survive, at a time when he was primed to apply these ideas to animal species. Darwin applied to his search for the Creator's laws the Whig social thinking of struggle for survival with no hand-outs. By December 1838 he was seeing a similarity between breeders selecting traits and a Malthusian Nature selecting from variants thrown up by chance so that "every part of newly acquired structure is fully practised and perfected", thinking this "the most beautiful part of my theory".
[edit] First writings on the theory
Darwin was well aware of the implication the theory had for the origin of humanity and the real danger to his career and reputation as an eminent geologist of being convicted of blasphemy. He worked in secret to consider all objections and prepare overwhelming evidence supporting his theory. He increasingly wanted to discuss his ideas with his colleagues, and in January 1842 sent a tentative description of his ideas in a letter to Lyell, who was then touring America. Lyell, dismayed that his erstwhile ally had become a Transmutationist, noted that Darwin "denies seeing a beginning to each crop of species".
Despite problems with illness, Darwin formulated a 35 page "Pencil Sketch" of his theory in June 1842 then worked it up into a larger "essay". The botanist Joseph Dalton Hooker became Darwin's mainstay, and late in 1845 Darwin offered his "rough Sketch" for comments without immediate success, but in January 1847 when Darwin was particularly ill Hooker took away a copy of the "Sketch". After some delays he sent a page of notes, giving Darwin the calm critical feedback that he needed. Darwin made a huge study of barnacles which established his credentials as a biologist and provided more evidence supporting his theory.
The publication of the anonymous Vestiges of the Natural History of Creation (1844) paved the way for the acceptance of Origin.
[edit] Publication
In the spring of 1856 Lyell drew Darwin's attention to a paper on the "introduction" of species written by Alfred Russel Wallace, a naturalist working in Borneo, and 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 which would have been required to publish in an academic journal. On 14 May 1856 he began a "sketch" account and, by July, had decided to produce a full technical treatise on species.
Darwin pressed on, overworking, and was throwing himself into his work with his book on Natural Selection well under way, when on 18 June 1858 he received a parcel from Wallace enclosing about twenty pages describing an evolutionary mechanism, an unexpected response to Darwin's recent encouragement, with a request to send it on to Lyell. Darwin wrote to Lyell that "your words have come true with a vengeance,... forestalled" and he would, "of course, at once write and offer to send [it] to any journal" that Wallace chose, adding that "all my originality, whatever it may amount to, will be smashed". Lyell and Hooker agreed that a joint paper should be presented at the Linnean Society, and on 1 July 1858 the Wallace and Darwin papers entitled respectively On the Tendency of Species to form Varieties; and on the Perpetuation of Varieties and Species by Natural Means of Selection were read out, to surprisingly little reaction.
On 20 July 1858 Darwin started work on an "abstract" trimmed from his Natural Selection, writing much of it from memory. Lyell made arrangements with the publisher John Murray, who agreed to publish the manuscript sight unseen, and to pay Darwin two-thirds of the net proceeds. Darwin had initially decided to call his book An abstract of an Essay/on the/Origin/of/Species and Varieties/Through natural selection/, but with Murray's persuasion it was eventually changed to the snappier title: On the Origin of Species with the title page adding by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life, a long book title as was common during the Victorian era.[8]
[edit] Publication of The Origin
The Origin was first published on 24 November 1859, price fifteen shillings. The book was offered to booksellers at Murray's autumn sale on 22 November, and all available copies were taken up immediately. In total 1250 copies were printed, but after deducting presentation and review copies, and five for Stationers' Hall copyright, around 1,170 copies were available for sale.[9] The second edition of 3,000 copies was quickly brought out on 7 January 1860,[10] and added "by the Creator" into the closing sentence, so that from then on it read "There is grandeur in this view of life, with its several powers, having been originally breathed by the Creator into a few forms or into one; and that, whilst this planet has gone circling 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."
During Darwin's lifetime the book went through six editions, with cumulative changes and revisions to deal with counter-arguments raised. The third edition came out in 1861, and the fourth in 1866, each with an increasing number of sentences rewritten or added. The fifth edition published on 10 February 1869 incorporated more changes again, and for the first time included Herbert Spencer's phrase "survival of the fittest".
In January 1871 Mivart published On the Genesis of Species, the cleverest and most devastating critique of natural selection in Darwin's lifetime. Darwin took it personally and from April to the end of the year made extensive revisions to the Origin, using the word "evolution" for the first time and adding a new chapter to refute Mivart. He told Murray of working men in Lancashire clubbing together to buy the 5th edition at fifteen shillings, and he wanted a new cheap edition to make it more widely available.
The sixth edition was published by Murray on 19 February 1872 with "On" dropped from the title, at a price halved to 7s. 6d. by using minute print. Sales increased from 60 to 250 a month.
[edit] On the Origin of Species, as presented
After the words "On the Origin of Species" on page i, page ii shows quotations.[11] The first, by William Whewell from his Bridgewater Treatise, sets out the idea that in natural theology events in the material world are brought about "by the establishment of general laws" rather than by individual miracles. The second by Francis Bacon from his Advancement of Learning argues that we should study both the the word of God in the Bible and the works of God in nature together, so that the works of God teach us how to interpret the word of God.[4] From the second to sixth editions, a third quotation is included, from the Analogy of Revealed Religion by the eighteenth century bishop Joseph Butler. This describes natural as meaning "stated, fixed or settled" by "an intelligent agent" who can equally carry out single supernatural miracles.[12]
These quotations relate theology to nature, and in the book Darwin includes various comments aiming to harmonise science and religion, in line with Isaac Newton's belief in the glory of a rational God who established a law-abiding cosmos rather than a capricious deity.[13] The quotations are followed by the title page (as illustrated above), then the index. The book then begins with the Introduction, though in the 6th edition this is preceded by An Historical Sketch giving due credit to his predecessors in ideas of evolution and natural selection.
[edit] Introduction
WHEN on board H.M.S. 'Beagle,' as naturalist, I was much struck with certain facts in the distribution of the inhabitants of South America, and in the geological relations of the present to the past inhabitants of that continent. These facts seemed to me to throw some light on the origin of species—that mystery of mysteries, as it has been called by one of our greatest philosophers.[14]
Darwin starts with a reference to the distribution of rheas, Galapagos tortoises and mockingbirds inspiring doubts in species being fixed, and the close relationship of the giant fossils he found to their small modern relatives on the same continent. He then cites the question which John Herschel had raised in correspondence with Charles Lyell just before Darwin met Herschel in South Africa.[15] Darwin mentions his years of work on his theory, and Wallace arriving at the same conclusion leading him to "publish this Abstract" of his incomplete work. He then outlines his ideas, and sets out its essence of his theory:
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.[16]
[edit] Variation under domestication and under nature
Chapter I discusses the considerable amount of variation of plants and animals in conditions of domestication.[17] Darwin partly attributes this to different conditions of life, and (incorrectly) to domestication itself se well as to changed habits producing an inherited effect. He discusses how domestication has been going on since the neolithic period, then turns in detail to his studies of domestic pigeons. "The diversity of the breeds is something astonishing", yet all show evidence of being descendants of the same species of rock pigeons. He describes breeding methods, and introduces the term artificial selection (though environmental changes, such as more food and protection from predators, were also factors).
In chapter II Darwin considers variation under nature,[18] and shows that the nineteenth-century definition of species was chiefly a matter of opinion, since the discovery of new linking forms often degraded species to varieties.
[edit] Struggle for existence, and natural selection
At the start of chapter III on struggle for existence Darwin reiterates how this results in varieties, "which I have called incipient species", becoming distinct species, grouped into genera.[19]
Owing to this struggle for life, any variation, however slight and from whatever cause proceeding, if it be in any degree profitable to an individual of any species, in its infinitely complex relations to other organic beings and to external nature, will tend to the preservation of that individual, and will generally be inherited by its offspring.... I have called this principle, by which each slight variation, if useful, is preserved, by the term of Natural Selection, in order to mark its relation to man's power of selection.[20]
In the 5th and 6th editions he added "But the expression often used by Mr. Herbert Spencer, of the Survival of the Fittest, is more accurate, and is sometimes equally convenient." [21]
He discusses the universal struggle for existence as shown by De Candolle and Lyell, emphasising that he uses the term "in a large and metaphorical sense, including dependence of one being on another". The rate of increase in population which would follow if all offspring survived leads to a Malthusian struggle: "It is the doctrine of Malthus applied with manifold force to the whole animal and vegetable kingdoms". In reviewing checks to such increase he discusses the complex interdependencies which we now term ecology, including the effects of the introduction of new species by colonists. He notes that competition is most severe between closely related forms, "which fill nearly the same place in the economy of nature".
Chapter IV then turns in detail to natural selection under the "infinitely complex and close-fitting.. mutual relations of all organic beings to each other and to their physical conditions of life".[22] Darwin takes as an example a country where a change in conditions leads to extinction of some species, possibly immigration of others more suited and, where suitable variations occur, descendants of species becoming increasingly adapted to the changing conditions. He does not suggest that every variation and every character must have a selection value, though it would be extremely rash to set down any characters as valueless to their owners. Importantly, he does not suggest that every individual with a favourable variation must be selected, or that the selected or favoured animals are better or higher, but merely that they are more adapted to their surroundings. Having no knowledge of Mendelian genetics, he tries to deal with anticipated blending of inherited characteristics.
Darwin then introduces what he calls sexual selection to explain seemingly non-funcional differences between sexes, as in beautiful plumage of birds. He draws attention to cross-breeding between varieties giving "vigour and fertility to the offspring", with close interbreeding having the opposite effect, in what he thinks may be a universal law. This explains features found in flowers which avoid self-fertilisation and attract insects to cross-pollinate.[23] He thinks that natural selection leading to new species is most favoured by isolation of a population, or by open areas with large populations leading to increased numbers of variations. The effect of natural selection in forming species is expected to be very slow, and often intermittent, but given the effectiveness of artificial selection, he "can see no limit to the amount of change, to the beauty and infinite complexity of the coadaptations between all organic beings, one with another and with their physical conditions of life, which may be effected in the long course of time by nature's power of selection." With the aid of a tree diagram and calculations he indicates the "divergence of character" from one original species into multiple new species and genera, branches stopping or falling off as extinction occurs, while fresh buds form new branches in "the great Tree of Life... with its ever branching and beautiful ramifications."[24]
[edit] Variation and heredity
One of the chief difficulties for Darwin and other naturalists in his time was that there was no agreed-upon model of heredity — in fact, the idea of heredity had not been completely separated conceptually from the idea of the development of the organism. Darwin himself saw variation and heredity as two essentially antagonistic forces, with most heredity working to preserve the fixity of a type rather than acting as the agent of species variability. Darwin's own model of heredity worked out in later works, which he dubbed "Pangenesis", was a mixture of a number of different ideas about heredity at the time. It contained what are now considered to be essentially Lamarckian aspects, whereby the effects of use and dis-use of different parts of the body in the parent could be transmitted to the child. Beyond this, it was essentially a model of "blended" heredity, by which the contributions of two parents (in the form of particles he called "gemmules") were roughly equal. Darwin was confident that even in this model, over long periods of time species would still be able to evolve.
It was not until the early 20th century that a model of heredity would become completely integrated with a model of variation, with the advent of the modern evolutionary synthesis known as neo-Darwinism. It is a common trope in the history of evolution and genetics written by scientists, rather than historians, to claim that Darwin's lack of an adequate model of heredity was the source of suspicion about his theory, but later historians of science have adequately documented the fact that this was not the source of most objections to Darwin, and that later scientists, such as Karl Pearson and the biometric school, could develop compelling models of evolution by natural selection with even a relatively simple "blending" model of heredity such as that used by Darwin.[25]
[edit] Compatibility with Lamarckian inheritance
Contrarily to a common opinion, Darwin did not rule out at first the possibility of inherited acquired traits, and even mentions it explicitly in chapter 7:
"When the first tendency was once displayed, methodical selection and the inherited effects of compulsory training in each successive generation would soon complete the work; and unconscious selection is still at work, as each man tries to procure, without intending to improve the breed, dogs which will stand and hunt best. On the other hand, habit alone in some cases has sufficed; no animal is more difficult to tame than the young of the wild rabbit; scarcely any animal is tamer than the young of the tame rabbit; but I do not suppose that domestic rabbits have ever been selected for tameness; and I presume that we must attribute the whole of the inherited change from extreme wildness to extreme tameness, simply to habit and long-continued close confinement".
Nevertheless, there is a distinction between Lamarck's theory and Darwin's one: while Darwin's theory stays valid whether acquired traits are transmitted or not, Lamarck's theory becomes inoperative if acquired traits cannot be transmitted.
