Part of a series on
Evolutionary Biology
Key topics Introduction to evolution Common descent Evidence of common descent
Processes and outcomes Population genetics Variation • Mutation Natural selection • Adaptation Polymorphism (biology) Genetic drift • Gene flow Speciation • Adaptive radiation Co-operation • Coevolution Divergent • Convergent Parallel evolution Extinction
Natural history Origin of Life • History of life Timeline of evolution Human evolution Phylogeny Biodiversity • Biogeography Classification • Cladistics Transitional fossil Extinction event
History of evolutionary theory Overview Timeline of paleontology History of paleontology Renaissance and Enlightenment Before Darwin Darwin • On the Origin of Species Before the Synthesis Modern evolutionary synthesis Molecular evolution • Evo-devo Current research
Fields and applications Applications of evolution Artificial selection Biosocial criminology Ecological genetics Evolutionary aesthetics Evolutionary anthropology Evolutionary computation Evolutionary economics Evolutionary ethics Evolutionary game theory Evolutionary linguistics Evolutionary medicine Evolutionary neuroscience Evolutionary physiology Evolutionary psychology Experimental evolution Phylogenetics Systematics Universal Darwinism
Social implications Theory and fact Social effect Controversy Objections Level of support
Evolutionary Biology Portal Category • Related topics • Book
v t e

The eclipse of Darwinism was a phrase used by Julian Huxley to describe the state of affairs prior to the modern evolutionary synthesis when evolution was widely accepted in scientific circles but relatively few biologists believed that natural selection was its primary mechanism.^[1][2] Historians of science such as Peter J. Bowler have used it as a label for the period within the history of evolutionary thought from the 1880s through the first couple of decades of the 20th century when a number of alternatives to natural selection were developed and explored, as many biologists considered natural selection to have been a wrong guess on Charles Darwin's part, and others felt it was of relatively minor importance.^[3][4]

There were four major alternatives to natural selection in the late 19th century. Theistic evolution was the belief that God directly guided evolution. The idea that evolution was driven by the inheritance of characteristics acquired during the life of the organism was called neo-Lamarckism. Orthogenesis was the belief that organisms were affected by internal forces or laws of development that drove evolution in particular directions, and saltationism was the idea that evolution was largely the product of large mutations that created new species in a single step.

Theistic evolution largely disappeared from the scientific literature by the end of the 19th century as direct appeals to supernatural causes came to be seen as unscientific. The other alternatives had significant followings well into the 20th century; it wasn't until developments in genetics made them seem increasingly untenable, and the development of population genetics and the modern evolutionary synthesis demonstrated the explanatory power of natural selection that they were largely abandoned. Ernst Mayr wrote that as late as 1930 most textbooks still emphasized such non-Darwinian mechanisms.^[5]

Extent[link]

Evolution was widely accepted in scientific circles within a few years after the publication of On the Origin of Species, but acceptance of natural selection as its driving mechanism was much less.^[6] By the end of the 19th century criticism of natural selection had reached the point that in 1903 the German botanist, Eberhardt Dennart, wrote that "We are now standing at the death bed of Darwinism", and in 1907 the Stanford University entomologist Vernon Lyman Kellogg who supported natural selection had to admit "... the fair truth is that the Darwinian selection theory, considered with regard to its claimed capacity to be an independently sufficient mechanical explanation of descent, stands today seriously discredited in the biological world." ^[7] Though he added that there were problems preventing the widespread acceptance of any of the alternatives, as large mutations seemed too uncommon, and there was no experimental evidence of mechanisms that could support either Lamarckism or orthogenesis.^[8] Ernst Mayr wrote that a survey of evolutionary literature and biology textbooks showed that as late as 1930 the belief that natural selection was the most important factor in evolution was a minority viewpoint with only a few population geneticists being strict selectionists.^[5]

Motivation for alternatives[link]

There were a variety of different factors that motivated people to propose other evolutionary mechanisms as alternatives to natural selection. Natural selection, with its emphasis on death and competition, did not appeal to some naturalists because they felt it was immoral, and left little room for teleology or the concept of progress in the development of life.^[9][10] Some of these scientists and philosophers, like St. George Jackson Mivart and Charles Lyell, who came to accept evolution but disliked natural selection, raised religious objections.^[11] Others, such as Herbert Spencer, the botanist George Henslow (son of Darwin's mentor John Stevens Henslow also a botanist), and Samuel Butler, felt that evolution was an inherently progressive process that natural selection alone was insufficient to explain. Still others, including the American paleontologists Edward Drinker Cope and Alpheus Hyatt, had an idealist perspective and felt that nature, including the development of life, followed orderly patterns that natural selection could not explain.^[12]

Some felt that natural selection would be too slow, given the estimates of the age of the earth and sun (10–100 million years) being made at the time by physicists such as Lord Kelvin, and some felt that natural selection could not work because at the time the models for inheritance involved blending of inherited characteristics, an objection raised by the engineer Fleeming Jenkin in a review of Origin written shortly after its publication.^[12][13] Another factor at the end of the 19th century was the rise of new faction of biologists, typified by geneticists like Hugo DeVries and Thomas Hunt Morgan, who wanted to recast biology as an experimental laboratory science. They distrusted the work of naturalists like Darwin and Alfred Russel Wallace, dependent on field observations of variation, adaptation, and biogeography, as being overly anecdotal. Instead they focused on topics like physiology, and genetics that could be easily investigated with controlled experiments in the lab, and discounted things like natural selection and even the degree to which organisms were adapted to their environment, which could not easily be tested experimentally.^[14]

Theistic evolution[link]

British science developed in the early 19th century on a basis of natural theology which saw the adaptation of fixed species as evidence that they had been specially created to a purposeful divine design. The philosophical concepts of German idealism inspired concepts of an ordered plan of harmonious creation, which Richard Owen reconciled with natural theology as a pattern of homology showing evidence of design. Similarly, Louis Agassiz saw the recapitulation theory as symbolising a pattern of the sequence of creations in which humanity was the goal of a divine plan. In 1844 Vestiges adapted Agassiz's concept into theistic evolutionism. Its anonymous author Robert Chambers proposed a "law" of divinely ordered progressive development, with transmutation of species as an extension of recapitulation theory. This popularised the idea, but it was strongly condemned by the scientific establishment. Agassiz remained forcefully opposed to evolution, and after he moved to America in 1846 his idealist argument from design of orderly development became very influential.^[15] In 1858 Owen cautiously proposed that this development could be a real expression of a continuing creative law, but distanced himself from transmutationists. Two years later in his review of Darwin's On the Origin of Species Owen attacked Darwin while at the same time openly supporting evolution,^[16] expressing belief in a pattern of transmutation by law-like means. This idealist argument from design was taken up by other naturalists such as George Jackson Mivart, and the Duke of Argyll who rejected natural selection altogether in favor of laws of development that guided evolution down preordained paths.^[17]

Many of Darwin's supporters accepted evolution on the basis that it could be reconciled with design. In particular, Asa Gray considered natural selection to be the main mechanism of evolution and sought to reconcile it with natural theology. He proposed that natural selection could be a mechanism in which the problem of evil of suffering produced the greater good of adaptation, but conceded that this had difficulties and suggested that God might influence the variations on which natural selection acted to guide evolution.^[18] For Darwin and Thomas Henry Huxley such pervasive supernatural influence was beyond scientific investigation, and George Frederick Wright, an ordained minister who was Gray's colleague in developing theistic evolution, emphasised the need to look for secondary or known causes rather than invoking supernatural explanations: "If we cease to observe this rule there is an end to all science and all sound science."^[19]

A secular version of this methodological naturalism was welcomed by a younger generation of scientists who sought to investigate natural causes of organic change, and rejected theistic evolution in science. By 1872 Darwinism in its broader sense of the fact of evolution was accepted as a starting point. Around 1890 only a few older men held onto the idea of design in science, and it had completely disappeared from mainstream scientific discussions by 1900. There was still unease about the implications of natural selection, and those seeking a purpose or direction in evolution turned to neo-Lamarckism or orthogenesis as providing natural explanations.^[20]

Neo-Lamarckism[link]

Jean-Baptiste Lamarck

Jean-Baptiste Lamarck had originally proposed a theory on the transmutation of species that was largely based on a progressive drive toward greater complexity. Lamarck also believed, as did many others at the time, that characteristics acquired during the course of an organism's life could be inherited by the next generation, and he saw this as a secondary evolutionary mechanism that produced adaptation to the environment. Typically, such characteristics included changes caused by the use or disuse of a particular organ. It was this mechanism of evolutionary adaptation through the inheritance of acquired characteristics that much later came to be known as Lamarckism.^[21] Although Alfred Russel Wallace completely rejected the concept in favor of natural selection, Charles Darwin always included what he called Effects of the increased Use and Disuse of Parts, as controlled by Natural Selection in On the Origin of Species, giving examples such as large ground feeding birds getting stronger legs through exercise, and weaker wings from not flying until, like the ostrich, they could not fly at all.^[22]

In the late 19th century the term neo-Lamarckism came to be associated with the position of naturalists who viewed the inheritance of acquired characteristics as the most important evolutionary mechanism. Advocates of this position included the British writer and Darwin critic Samuel Butler, the German biologist Ernst Haeckel, the American paleontologists Edward Drinker Cope and Alpheus Hyatt, and the American entomologist Alpheus Packard. They considered Lamarckism to be more progressive and thus philosophically superior to Darwin's idea of natural selection acting on random variation. Butler and Cope both believed that this allowed organisms to effectively drive their own evolution, since organisms that developed new behaviors would change the patterns of use of their organs and thus kick-start the evolutionary process. In addition, Cope and Haeckel both believed that evolution was a progressive process. The idea of linear progress was an important part of Haeckel's recapitulation theory of evolution, which held that the embryological development of an organism repeats its evolutionary history. Cope and Hyatt looked for, and thought they found, patterns of linear progression in the fossil record.^[23][24] Packard argued that the loss of vision in the blind cave insects he studied was best explained through a Lamarckian process of atrophy through disuse combined with inheritance of acquired characteristics. Packard also wrote a book about Lamarck and his writings.^[23][25]

Many American proponents of neo-Lamarckism were strongly influenced by Louis Agassiz and a number of them, including Hyatt and Packard, were his students. Agassiz had an idealistic view of nature, connected with natural theology, that emphasized the importance of order and pattern. Agassiz never accepted evolution; his followers did, but they continued his program of searching for orderly patterns in nature, which they considered to be consistent with divine providence, and preferred evolutionary mechanisms like neo-Lamarckism and orthogenesis that would be likely to produce them.^[23][25]

In Britain the botanist George Henslow, the son of John Stevens Henslow who had been Darwin's mentor at the University of Cambridge, was an important advocate of neo-Lamarckism. He studied how environmental stress affected the development of plants, and he wrote that the variations induced by such environmental factors could largely explain evolution. The science historian Peter J. Bowler writes that, as was typical of many 19th century Lamarckians, Henslow did not appear to understand the need to demonstrate that such environmentally induced variations would be inherited by descendants that developed in the absence of the environmental factors that produced them, but merely assumed that they would be.^[26]

Critics of neo-Lamarckism pointed out that no one had ever produced solid evidence for the inheritance of acquired characteristics. The experimental work of the German biologist August Weismann resulted in the germ plasm theory of inheritance. This led him to declare that inheritance of acquired characteristics was flatly impossible, since the Weismann barrier would prevent any changes that occurred to the body after birth from being inherited by the next generation. Despite these criticisms, neo-Lamarckism remained the most popular alternative to natural selection at the end of the 19th century, and would remain the position of some naturalists well into the 20th century.^[24][27]

Baldwin effect[link]

As a consequence of the debate over the viability of neo-Lamarckism in the 1890s, James Mark Baldwin, Henry Fairfield Osborne and C. Lloyd Morgan all independently proposed a mechanism where new learned behaviors could cause the evolution of new instincts and physical traits through natural selection without resort to the inheritance of acquired characteristics. They proposed that if individuals in a species benefited from learning a particular new behavior, the ability to learn that behavior could be favored by natural selection, and the end result would be the evolution of new instincts and eventually new physical adaptations. This became known as the Baldwin effect and it has remained a topic of debate and research in evolutionary biology ever since.^[28]

Orthogenesis[link]

Henry Fairfield Osborn's 1918 book Origin and Evolution of Life claimed the evolution of Titanothere horns was an example of an orthogenetic trend in evolution.

Orthogenetic evolution was the hypothesis that life has an innate tendency to change, in a unilinear fashion in a particular direction. The term orthogenesis was popularized by a Theodor Eimer a German zoologist. Eimer also believed in Lamarckian inheritance of acquired characteristics, but he felt that internal laws of growth determine which characteristics would be acquired and guided the long term direction of evolution down certain paths.^[29]

Orthogenesis had a significant following in the 19th century, and its proponents included the Russian biologist Leo S. Berg, and Henry Fairfield Osborn, an American paleontologist.^[30] Orthogenesis was particularly popular among some paleontologists, who believed that the fossil record showed patterns of gradual and constant unidirectional change. Those who accepted this idea, however, did not necessarily accept that the mechanism driving orthogenesis was teleological (goal-directed). They also thought orthogenetic trends were not adaptive; in fact they felt that in some cases they led to developments that were detrimental to the organism, such as the large antlers of the Irish elk that they believed led to the animal's extinction.^[29]

Support for the orthogenesis hypothesis began to decline during the modern evolutionary synthesis in the 1940s when it became apparent that it could not explain the complex branching patterns of evolution revealed by statistical analysis of the fossil record by paleontologists. A few hung on to the idea of orthogenesis as late as the 1950s by claiming that the processes of macroevolution, the long term trends in evolution, were distinct from the processes of microevolution.^[12][13]

Saltationism and mutation theory[link]

Saltationism was the idea that new species arise as a result of large mutations. It was seen as a much faster alternative to the Darwinian concept of a gradual process of small random variations being acted on by natural selection. It was popular with early geneticists such as Hugo de Vries, who along with Carl Correns helped rediscover Gregor Mendel's laws of inheritance in 1900, William Bateson a British zoologist who switched to genetics, and early in his career Thomas Hunt Morgan. Some of these geneticists developed it into the mutation theory of evolution.^[31][32]

The mutation theory of evolution held that species went through periods of rapid mutation, possibly as a result of environmental stress, that could produce multiple mutations, and in some cases completely new species, in a single generation. Its originator was the Dutch botanist Hugo de Vries. De Vries looked for evidence of mutation extensive enough to produce a new species in a single generation and thought he found it with his work breeding the evening primrose of the genus Oenothera, which he started in 1886. The primroses de Vries worked with seemed to be constantly producing new vareties with striking variations in form and color, some of which appeared to be new species because plants of the new generation could only be crossed with one another, not with their parents. DeVries himself allowed a role for natural selection in determining which new species would survive, but some of those influenced by his work, including Morgan, felt that natural selection was not necessary at all. DeVries's ideas were very influential in the first two decades of the 20th century as some felt mutation theory could explain the sudden emergence of new forms in the fossil record and research on Oenothera spread all over the world. Though some of his critics, which included many field naturalists, wondered why no other organism seemed to show the same kind of rapid mutation.^[33]

Morgan was a supporter of de Vries's mutation theory and was hoping to gather evidence in favor of it when he started working with the fruit fly Drosophila melanogaster in his lab in 1907. However, it was a researcher in that lab, Hermann Joseph Muller, who determined in 1918 that the new varieties de Vries had observed while breeding Oenothera were the result of polyploid hybrids rather than rapid genetic mutation.^[34] While they were doubtful of the importance of natural selection, the work of geneticists like Morgan, Bateson, DeVries and others from 1900-1915 established Mendelian genetics linked to chromosomal inheritance, which validated August Weismann's criticism of neo-Lamarckian evolution by discounting the inheritance of acquired characteristics. The work in Morgan's lab with Drosphila also undermined the concept of orthogenesis by demonstrating the random nature of mutation.^[35]

End of the eclipse[link]

Biston betularia f. typica is the white-bodied form of the peppered moth.

Biston betularia f. carbonaria is the black-bodied form of the peppered moth. In 1924 J.B.S. Haldane published a statistical analysis of the evolution of industrial melanism in peppered moths as an example of natural selection in a real world population.^[36]

During the period 1916-1932, the discipline of population genetics developed largely through the work of the geneticists Ronald Fisher, J.B.S. Haldane, and Sewall Wright. Their work recognized that the vast majority of mutations produced small effects that served to increase the genetic variability of a population rather than creating new species in a single step as the saltationists assumed, and they were able to produce statistical models of population genetics that included Darwin's concept of natural selection as the driving force of evolution.^[37]

Developments in the field of genetics made many field naturalists such as Bernhard Rensch and Ernst Mayr abandon neo-Lamarckian ideas about evolution in the early 1930s.^[38] By the late 1930s biologists like Mayr and Theodosius Dobzhansky had synthesized the ideas of population genetics with the knowledge of field naturalists about the amount of genetic diversity in wild populations, and the importance of genetically distinct sub populations (especially sub populations partially or fully isolated from one another by geographical barriers) to begin the modern evolutionary synthesis.^[39] In 1944 George Gaylord Simpson integrated paleontology into the synthesis by statistically analyzing the fossil record to show that it was consistent with the branching non-directional form of evolution predicted by the modern synthesis, and in particular that the linear trends cited by earlier paleontologists in support of Lamarckism and orthogenesis did not stand up to careful analysis.^[40] Mayr wrote that by the end of the synthesis natural selection together with chance mechanisms like genetic drift had become the universal explanation for evolutionary change.^[5]

See also[link]

• History of evolutionary thought
• Objections to evolution
• Modern evolutionary synthesis

Notes[link]

References[link]

Look up eclipse in Wiktionary, the free dictionary.

An eclipse is an astronomical event.

Eclipse may also refer to:

Computing[link]

• ECLIPSE (reservoir simulator), a fluid logic simulator
• Eclipse (software), a software development platform
  • Eclipse Foundation, a nonprofit organization to develop Eclipse (Software) projects
• Eclipse (suite), ECSS Compliant Toolset for Information and Projects Support of Enterprises in Space
• ECLiPSe, a constraint logic programming system
• Eclipse Internet, an Internet service provider
• Alias Eclipse, a professional image-editing application
• Data General Eclipse, a line of minicomputers

Music[link]

Albums[link]

• Eclipse (Amorphis album)
• Eclipse (Autumn Tears album)
• Eclipse (CANO album)
• Eclipse (Five Star album)
• Eclipse (G.G.F.H. album)
• Eclipse (Journey album)
• Eclipse (Smokie album)
• Eclipse (Yngwie Malmsteen album)
• A Futuro Primitivo album
• A Veil of Maya album
• Esenciales: Eclipse, an album by Maná
• The Twilight Saga: Eclipse (soundtrack)

Other[link]

• "Eclipse" (Pink Floyd song), appearing on The Dark Side of the Moon
• Eclipse Records, a record label
• A song by John Denver on the album Back Home Again
• A song by Robyn on the album Robyn
• A song by Apoptygma Berzerk on the album Welcome to Earth

Sport[link]

• Eclipse (horse), an 18th-century racehorse
  • Eclipse Award, a horse racing award
  • Eclipse Stakes, a horse race
• Louisville Eclipse, a professional baseball team
• Phoenix Eclipse, a professional basketball team

Publications[link]

• Eclipse (Banville novel), a 2000 novel by John Banville
• Eclipse (Bedford novel), a 2005 science fiction novel by K. A. Bedford
• Eclipse (Meyer novel), a 2007 book in the Twilight series by Stephenie Meyer
• Eclipse (Warriors), a book in the Warriors series by Erin Hunter
• Eclipse Trilogy, a series of science fiction novels by John Shirley
• Eclipse Comics, an American comic book publisher
  • Eclipse Magazine, a black-and-white anthology published by Eclipse Comics
  • Eclipse Monthly, a full-color anthology published by Eclipse Comics
• The Eclipse: A Memoir of Suicide, a memoir by Antonella Gambotto-Burke
• L'Éclipse, a 19th-century French newspaper

Film and television[link]

• The Eclipse: Courtship of the Sun and Moon, a 1907 film by Georges Méliès
• Eclipse (1962 film), by Michelangelo Antonioni
• Eclipse (1994 film), by Jeremy Podeswa
• The Eclipse (2009 film), a 2009 film by Conor McPherson
• Eclipse (DVD), a line of DVD sets from the Criterion Collection
• The Twilight Saga: Eclipse, a 2010 film adaptation of the Meyer novel
• Eclipse Music TV, a TV show
• "The Eclipse" (Heroes), a television episode
• "Eclipsed" (The Penguins of Madagascar episode)
• Chief Eclipse, a character in the anime series Kiddy Grade
• "The Day of Black Sun Part 2: The Eclipse," an Avatar: The Last Airbender episode
• A French film production company founded in 1906 by Charles Urban
• A Star Destroyer spaceship in the Star Wars universe

Aircraft, cars, and ships[link]

• Eclipse Aviation, an aircraft manufacturer
  • Eclipse 500, a jet aircraft produced from 2006 to 2008
  • Eclipse 400, a jet aircraft developed but never produced
• Eclipse class cruiser, a 19th-century class of British Royal Navy cruisers
• HMS Eclipse, the name of several British Royal Navy ships
• Celebrity Eclipse, a cruise ship
• Eclipse (yacht), owned by Russian billionaire Roman Abramovich
• Mitsubishi Eclipse, a sports car
• Phase 3 Eclipse, ultralight aircraft
• Wright Eclipse, a bus body
• USS Eclipse (SP-417), a United States Navy patrol vessel in commission from 1917 to 1919

Places[link]

• Eclipse Island (Western Australia), a barren island near Albany
• Eclipse Island, Queensland, Australia, an island of the Great Palm Island group
• Eclipse Park, the name of two former baseball grounds in Kentucky, United States
• Eclipse Park (Milwaukee), a former baseball ground in Wisconsin, United States

Products[link]

• Eclipse (breath freshener), a Wrigley brand of chewing gum and breath mint
• Eclipse (cigarette), an American cigarette brand
• ESP Eclipse, an electric guitar model

Other uses[link]

• Eclipse (video game)
• Eclipse plumage, a phase in the coloring of some birds
• A caste in the roleplaying game Exalted
• A car audio and navigation brand by Fujitsu Ten

See also[link]

• Total Eclipse (disambiguation)
• Ellipsis
• Ellipse

This disambiguation page lists articles associated with the same title. If an internal link led you here, you may wish to change the link to point directly to the intended article.

Charles Darwin
Darwin, aged 45 in 1854, by then working towards publication of On the Origin of Species
Born	Charles Robert Darwin (1809-02-12)12 February 1809 Mount House, Shrewsbury, Shropshire, England
Died	19 April 1882(1882-04-19) (aged 73) Down House, Downe, Kent, England
Residence	England
Citizenship	British
Nationality	British
Fields	Naturalist
Institutions	Geological Society of London
Alma mater	(tertiary education): University of Edinburgh (medicine) University of Cambridge (ordinary Bachelor of Arts)
Academic advisors	John Stevens Henslow Adam Sedgwick
Known for	The Voyage of the Beagle On the Origin of Species evolution by natural selection, common descent
Influences	Alexander von Humboldt John Herschel Charles Lyell
Influenced	Joseph Dalton Hooker Thomas Henry Huxley George Romanes Ernst Haeckel Sir John Lubbock
Notable awards	Royal Medal (1853) Wollaston Medal (1859) Copley Medal (1864)
Spouse	Emma Darwin (1839-1896)
Signature

Part of a series on
Evolutionary Biology
Key topics Introduction to evolution Common descent Evidence of common descent
Processes and outcomes Population genetics Variation • Mutation Natural selection • Adaptation Polymorphism (biology) Genetic drift • Gene flow Speciation • Adaptive radiation Co-operation • Coevolution Divergent • Convergent Parallel evolution Extinction
Natural history Origin of Life • History of life Timeline of evolution Human evolution Phylogeny Biodiversity • Biogeography Classification • Cladistics Transitional fossil Extinction event
History of evolutionary theory Overview Timeline of paleontology History of paleontology Renaissance and Enlightenment Before Darwin Darwin • On the Origin of Species Before the Synthesis Modern evolutionary synthesis Molecular evolution • Evo-devo Current research
Fields and applications Applications of evolution Artificial selection Biosocial criminology Ecological genetics Evolutionary aesthetics Evolutionary anthropology Evolutionary computation Evolutionary economics Evolutionary ethics Evolutionary game theory Evolutionary linguistics Evolutionary medicine Evolutionary neuroscience Evolutionary physiology Evolutionary psychology Experimental evolution Phylogenetics Systematics Universal Darwinism
Social implications Theory and fact Social effect Controversy Objections Level of support
Evolutionary Biology Portal Category • Related topics • Book
v t e

Charles Robert Darwin, FRS (12 February 1809 – 19 April 1882) was an English naturalist.^[I] He established that all species of life have descended over time from common ancestors,^[1] and proposed the scientific theory that this branching pattern of evolution resulted from a process that he called natural selection.^[2]

Darwin published his theory with compelling evidence for evolution in his 1859 book On the Origin of Species, overcoming scientific rejection of earlier concepts of transmutation of species.^[3][4] By the 1870s the scientific community and much of the general public had accepted evolution as a fact. However, many favoured competing explanations and it was not until the emergence of the modern evolutionary synthesis from the 1930s to the 1950s that a broad consensus developed in which natural selection was the basic mechanism of evolution.^[5][6] In modified form, Darwin's scientific discovery is the unifying theory of the life sciences, explaining the diversity of life.^[7][8]

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.^[9] 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.^[10]

Puzzled by the geographical distribution of wildlife and fossils he collected on the voyage, Darwin began detailed investigations and in 1838 conceived his theory of natural selection.^[11] Although he discussed his ideas with several naturalists, he needed time for extensive research and his geological work had priority.^[12] 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.^[13] Darwin's work established evolutionary descent with modification as the dominant scientific explanation of diversification in nature.^[5] 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.^[14]

In recognition of Darwin's pre-eminence as a scientist, he was honoured by a major ceremonial funeral in Westminster Abbey, where he was buried close to John Herschel and Isaac Newton.^[15] Darwin has been described as one of the most influential figures in human history.^[16][17]

Life[link]

Childhood and education[link]

The seven-year-old Charles Darwin in 1816.

Charles Robert Darwin was born in Shrewsbury, Shropshire, England on 12 February 1809 at his family home, the Mount.^[18] 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.^[19]

Darwin spent the summer of 1825 as an apprentice doctor, helping his father treat the poor of Shropshire, before going to the University of Edinburgh Medical School with his brother Erasmus in October 1825. He found lectures dull and surgery distressing, so neglected his studies. He learned taxidermy from John Edmonstone, a freed black slave who had accompanied Charles Waterton in the South American rainforest, and often sat with this "very pleasant and intelligent man".^[20]

In Darwin's second year he joined the Plinian Society, a student natural history group whose debates strayed into radical materialism. He assisted Robert Edmond Grant's investigations of the anatomy and life cycle of marine invertebrates in the Firth of Forth, and on 27 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.^[21] 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.^[22]

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. As Darwin was unqualified for the Tripos, he joined the ordinary degree course in January 1828.^[23] He preferred riding and shooting to studying. His cousin William Darwin Fox introduced him to the popular craze for beetle collecting which Darwin 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 his own exams drew near, Darwin focused on his studies and was delighted by the language and logic of William Paley's Evidences of Christianity.^[24] In his final examination in January 1831 Darwin did well, coming tenth out of 178 candidates for the ordinary degree.^[25]

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.^[26] 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.^[27] 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.^[28] 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.^[29]

[edit] Voyage of the Beagle

The voyage of the Beagle

Beginning on 27 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.^[5][30] 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.^[31] 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.^[32] Despite suffering badly from seasickness, Darwin wrote copious notes while on board the ship. Most of his zoology notes are about marine invertebrates, starting with plankton collected in a calm spell.^[30][33]

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,^[II] and Darwin saw things Lyell's way, theorising and thinking of writing a book on geology.^[34] In Brazil Darwin was delighted by the tropical forest,^[35] but detested the sight of slavery.^[36]

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.^[37][38] 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.^[39][40] 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.^[41][42]

As HMS Beagle surveyed the coasts of South America, Darwin theorised about geology and extinction of giant mammals.

Three Fuegians on board, who had been seized during the first Beagle voyage and had spent a year in England, were taken back to Tierra del Fuego as missionaries. Darwin found them friendly and civilised, yet their relatives seemed "miserable, degraded savages", as different as wild from domesticated animals.^[43] To Darwin the difference showed cultural advances, not racial inferiority. Unlike his scientist friends, he now thought there was no unbridgeable gap between humans and animals.^[44] A year on, the mission had been abandoned. The Fuegian they had named Jemmy Button lived like the other natives, had a wife, and had no wish to return to England.^[45]

Darwin experienced an earthquake in Chile and saw signs that the land had just been raised, including mussel-beds stranded above high tide. High in the Andes he saw seashells, and several fossil trees that had grown on a sand beach. He theorised that as the land rose, oceanic islands sank, and coral reefs round them grew to form atolls.^[46][47]

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.^[48][49] 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.^[50] He found the Aborigines "good-humoured & pleasant", and noted their depletion by European settlement.^[51]

The Beagle investigated how the atolls of the Cocos (Keeling) Islands had formed, and the survey supported Darwin's theorising.^[47] FitzRoy began writing the official Narrative of the Beagle voyages, and after reading Darwin's diary he proposed incorporating it into the account.^[52] Darwin's Journal was eventually rewritten as a separate third volume, on natural history.^[53]

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".^[54] 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".^[55] He later wrote that such facts "seemed to me to throw some light on the origin of species".^[56]

Inception of Darwin's evolutionary theory[link]

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.^[57] 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.^[58]

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.^[59][38] These extinct creatures were related to living species in South America.^[60]

In mid-December Darwin took lodgings in Cambridge to organise work on his collections and rewrite his Journal.^[61] 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.^[62]

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,^[63] 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,^[64] 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.^[54]

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.^[65] The two rheas were also distinct species, and on 14 March Darwin announced how their distribution changed going southwards.^[66]

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.^[67]

Overwork, illness, and marriage[link]

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 2010.^[68] He stretched the funding to include his planned books on geology, and agreed unrealistic dates with the publisher.^[69] As the Victorian era began, Darwin pressed on with writing his Journal, and in August 1837 began correcting printer's proofs.^[70]

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.^[71]

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.^[72] 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.^[5][73] Over time his research drew on information from his relatives and children, the family butler, neighbours, colonists and former shipmates.^[74] 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.^[75]

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.^[76]

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.^[77]

Darwin chose to marry his cousin, Emma Wedgwood.

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."^[78] 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.^[79]

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..."^[80]

Malthus asserted that unless human population is kept in check, it increases in a geometric progression and soon exceeds food supply in what is known as a Malthusian catastrophe.^[5] 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.^[5][81] 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.^[5] 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",^[82] thinking this comparison "a beautiful part of my theory".^[83]

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.^[84] 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.^[85]

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.^[86]

Preparing the theory of natural selection for publication[link]

Darwin in 1842 with his eldest son, William Erasmus Darwin

Darwin now had the framework of his theory of natural selection "by which to work",^[87] as his "prime hobby".^[88] 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.^[5] 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.^[89]

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.^[90] 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".^[91]

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.^[92] To escape the pressures of London, the family moved to rural Down House in September.^[93] On 11 January 1844 Darwin mentioned his theorising to the botanist Joseph Dalton Hooker, writing with melodramatic humour "it is like confessing a murder".^[94][95] 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."^[96]

Darwin's "sandwalk" at Down House was his usual "Thinking Path".^[97]

By July, Darwin had expanded his "sketch" into a 230-page "Essay", to be expanded with his research results if he died prematurely.^[98] 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.^[99][100]

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.^[101] 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.^[102]

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.^[103] 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.^[104]

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.^[105] In 1853 it earned him the Royal Society's Royal Medal, and it made his reputation as a biologist.^[106] 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".^[107]

Publication of the theory of natural selection[link]

Charles Darwin, aged 46 in 1855, by then working towards publication of his theory of natural selection. He wrote to Hooker about this portrait, "if I really have as bad an expression, as my photograph gives me, how I can have one single friend is surprising."^[108]

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 Law which has Regulated the Introduction of New 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."^[109]

Darwin's book was only partly written when, on 18 June 1858, he received a paper from Wallace describing natural selection. Shocked that he had been "forestalled", Darwin sent it on that day to Lyell, as requested by Wallace ^[110][111] , and although Wallace had not asked for publication, Darwin 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. After some discussion, 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.^[112]

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.^[113] 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."^[114] 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.^[115]

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.^[116] In the book, Darwin set out "one long argument" of detailed observations, inferences and consideration of anticipated objections.^[117] His only allusion to human evolution was the understatement that "light will be thrown on the origin of man and his history".^[118] 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.^[119]

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.^[120]

Responses to publication[link]

During the Darwin family's 1868 holiday in her Isle of Wight cottage, Julia Margaret Cameron took portraits showing the bushy beard Darwin grew between 1862 and 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.^[121]

The book aroused international interest, with less controversy than had greeted the popular Vestiges of the Natural History of Creation.^[122] 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.^[123] Darwin had only said "Light will be thrown on the origin of man",^[124] but the first review claimed it made a creed of the "men from monkeys" idea from Vestiges.^[125] Amongst early favourable responses, Huxley's reviews swiped at Richard Owen, leader of the scientific establishment Huxley was trying to overthrow.^[126] In April, Owen's review attacked Darwin's friends and condescendingly dismissed his ideas, angering Darwin,^[127] but Owen and others began to promote ideas of supernaturally guided evolution.^[128]

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".^[129] 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".^[130] Asa Gray discussed teleology with Darwin, who imported and distributed Gray's pamphlet on theistic evolution, Natural Selection is not inconsistent with Natural Theology.^[129][131] 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.^[129][132]

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,^[129] 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.^[133]

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.^[134] Lobbying brought Darwin Britain's highest scientific honour, the Royal Society's Copley Medal, awarded on 3 November 1864.^[135] That day, Huxley held the first meeting of what became the influential X Club devoted to "science, pure and free, untrammelled by religious dogmas".^[136] 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.^[137]

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.^[138] Darwin's theory also resonated with various movements at the time^[III] and became a key fixture of popular culture.^[IV] 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.^[121]

[edit] Descent of Man, sexual selection, and botany

By 1878, an increasingly famous Darwin had suffered years of illness.

More detailed articles cover Darwin's life from Orchids to Variation, from Descent of Man to Emotions and from Insectivorous Plants to Worms

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.^[139] Admiring visitors included Ernst Haeckel, a zealous proponent of Darwinismus incorporating Lamarckism and Goethe's idealism.^[140] Wallace remained supportive, though he increasingly turned to Spiritualism.^[141]

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.^[142]

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.^[134] 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.^[143] 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."^[144] 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."^[145]

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.

Death and legacy[link]

He died at Down House on 19 April 1882. 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".^[146] He had expected to be buried in St Mary's churchyard at Downe, but at the request of Darwin's colleagues, after public and parliamentary petitioning, William Spottiswoode (President of the Royal Society) arranged for Darwin to be honoured by a major ceremonial funeral and burial in Westminster Abbey, close to John Herschel and Isaac Newton.^[15][147]

Darwin had convinced most scientists that evolution as descent with modification was correct, and he was regarded as a great scientist who had revolutionised ideas. Though few agreed with his view that "natural selection has been the main but not the exclusive means of modification", he was honoured in June 1909 by more than 400 officials and scientists from across the world who met in Cambridge to commemorate his centenary and the fiftieth anniversary of On the Origin of Species.^[148] During this period, which has been called "the eclipse of Darwinism", scientists proposed various alternative evolutionary mechanisms which eventually proved untenable. The development of the modern evolutionary synthesis from the 1930s to the 1950s, incorporating natural selection with population genetics and Mendelian genetics, brought broad scientific consensus that natural selection was the basic mechanism of evolution. This synthesis set the frame of reference for modern debates and refinements of the theory.^[6]

Children[link]

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.^[9] 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.^[149] Despite his fears, most of the surviving children and many of their descendants went on to have distinguished careers (see Darwin-Wedgwood family).^[150]

Of his surviving children, George, Francis and Horace became Fellows of the Royal Society,^[151] distinguished as astronomer,^[152] 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.^[153]

Views and opinions[link]

Religious views[link]

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.^[154]

Darwin's family tradition was nonconformist Unitarianism, while his father and grandfather were freethinkers, and his baptism and boarding school were Church of England.^[19] When going to Cambridge to become an Anglican clergyman, he did not doubt the literal truth of the Bible.^[24] He learned 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.^[26][27] On board the Beagle, Darwin was quite orthodox and would quote the Bible as an authority on morality.^[155] He looked for "centres of creation" to explain distribution,^[48] and related the antlion found near kangaroos to distinct "periods of Creation".^[50]

By his return he was critical of the Bible as history, and wondered why all religions should not be equally valid.^[155] 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.^[84] 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,^[156] 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.^[131] 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 was reluctant to give up the idea of God as an ultimate lawgiver. He was increasingly troubled by the problem of evil.^[157][158]

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,^[159] but from around 1849 would go for a walk on Sundays while his family attended church.^[154] He considered it "absurd to doubt that a man might be an ardent theist and an evolutionist"^[160][161] 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."^[84][160]

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.^[162]

Human society[link]

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.^[163] 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.^[164] Darwin was strongly against slavery, against "ranking the so-called races of man as distinct species", and against ill-treatment of native people.^[165][VI]

Darwin was intrigued 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.^[166] Francis Galton named this field of study "eugenics" in 1883.^[V]

Evolutionary social movements[link]

Caricature from 1871 Vanity Fair

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.

Thomas Malthus had 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.^[167] Evolution was by then 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.^[168]

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. 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.^[169] Darwin himself insisted that social policy should not simply be guided by concepts of struggle and selection in nature.^[170]

After the 1880s a eugenics movement developed on ideas of biological inheritance, and for scientific justification of their ideas appealed to some concepts of Darwinism. In Britain, most shared Darwin's cautious views on voluntary improvement and sought to encourage those with good traits in "positive eugenics". During the "Eclipse of Darwinism" a scientific foundation for eugenics was provided by Mendelian genetics. Negative eugenics to remove the "feebleminded" were popular in America, Canada and Australia, and eugenics in the United States introduced compulsory sterilization laws, followed by several other countries. Subsequently, Nazi eugenics brought the field into disrepute.^[V]

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.^[171][167]

Commemoration[link]

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,^[172] and the nearby Mount Darwin in the Andes was named in celebration of Darwin's 25th birthday.^[173] 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.^[174]

More than 120 species and nine genera have been named after Darwin.^[175] 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.^[176]

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.^[177]

Darwin has been commemorated in the UK, with his portrait printed on the reverse of £10 banknotes printed along with a hummingbird and HMS Beagle, issued by the Bank of England.^[178]

A life size seated statue of Darwin can be seen in the main hall of the Natural History Museum in London. ^[179]

Works[link]

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 The Expression of the 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.^[180][181]

See also[link]

Notes[link]

Citations[link]