Development of Darwin's theory

The Development of Darwin's theory began with a search for explanations of contradictions in current Creationist ideas, and lead him to formulate his theory of evolution which was eventually published in his book On the Origin of Species.

Influences - before Darwin's theory

In the 16th century discoveries showing the extinction of species were explained by catastrophism. This propounded the belief 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). The extinct organisms could then be observed in the fossil record and their replacements were considered to be immutable. This explanation agreed with the story of the Flood in the Bible, and with the observation that in the fossil record, species remained constant until replaced by others, and was supported by the English scientific establishment which was dominated by the Church of England.

By the early 19th century, several alternative and radical ideas started to emerge. Charles's grandfather Erasmus Darwin hypothesized that all warm-blooded animals sprang from a single living "filament" long, long ago. Another theory was developed by Jean-Baptiste Lamarck (1744—1829), who observed that every new generation inherits some characteristics of its ancestors. His suggested mechanism for this process was that an individual's traits or organs became enhanced with repeated use, and weakened or removed by disuse. These changes would then be passed directly on to its offspring. As well as being developed in France, these theories were supported by Radicals in Britain like Robert Edmund Grant and developed into the idea of Transmutation. Another important influence on radical thought was the work of Thomas Malthus on populations, which influenced the Whig Poor Law of the 1830s.

From 1830 to 1833, the eminent British geologist and clergyman Sir Charles Lyell released a three volume publication called Principles of Geology which effectively rejected the Catastrophism Theory. This gave additional support to the concept of uniformitarianism, which stated that the Earth's surface gradually altered over eons of time by the constant action of natural geological processes. In the second volume Lyell set out a gradualist variation of Creationism in which each species had its "centre of creation" and was designed for the habitat, but would go extinct when the habitat changed. To Lyell's delight these ideas were developed by John Herschel and by Charles Babbage with the concept that God set up laws that operated to produce species, as a divine programmer. Another theory was explained to Darwin by Richard Owen who followed Johannes Peter Müller in thinking that living matter had an "organising energy", a life-force that directed the growth of tissues and also determined the lifespan of the individual and of the species.

While the scientific establishment was buzzing with these theories, plant and animal breeders were developing practical knowledge and ideas. When Darwin investigated their knowledge he found a pamphlet by Sir John Sebright with a passage reading: "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. In cold or barren countries no animals can live to the age of maturity, but those who have strong constitutions; the weak and the unhealthy do not live to propagate their infirmities."

Development of Darwin's theory

During the Voyage of the Beagle Charles Darwin became convinced by Lyell's uniformitarianism, and puzzled over how various theories of creation fitted the evidence he saw. He returned with his reputation established as a theoretical geologist, and set about getting his huge collection of specimens properly assessed by experts as well as writing books based on his notes. Richard Owen showed that the fossils 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.

Transmutation

Early in 1837 Darwin was speculating on transmutation in his "Red Notebook" which he had begun on the Beagle. At this time, when the Revd. William Whewell recruited him to the establishment position of secretary of the Geological Society, Darwin was privately scorning Whewell's faith in a human-centred universe being perfectly adapted to man and writing of "my theory" which he thought "would give zest to recent & Fossil Comparative Anatomy", transforming the "whole metaphysics". In July 1837 as his speculation deepened he started the first of a series of secret notebooks on transmutation.

Darwin's ideas fitted with the radical Unitarianism of his brother Erasmus's circle including Harriet Martineau, but were heretical to his Anglican friends in the scientific establishment. Such "Materialist" ideas had been seized on by socialist agitators, red Lamarckians who stirred the mob to overthrow the social order and even demanded the vote for working men! The establishment and the Tory press was quick to crush such ideas, using the full force of the law at a time when blasphemy was a criminal offence. Many were denounced and overthrown for such scandalous ideas, including the surgeon William Lawrence who was forced to resign his post and lost copyright on his book Lectures on Man. This book was promptly pirated by the notorious agitator and pornography publisher William Benbow, then published in cheap editions such as the copy which Darwin now read. As a result Darwin was secretive and very cautious in even hinting about his ideas to the friends he was bursting to share discussions with.

Animal observations

By February 1838 Darwin was on to a new pocketbook, the maroon C notebook, and was investigating the breeding of domestic animals. He found the newspaper wholesaler William Yarrell at the Zoological museum a fund of knowledge, and questioned if breeders weren't going against nature in picking varieties. He was now writing of Descent rather than transmutation, and hinting at ideas of adaption to climate. After reading the pamphlet by Yarrell's friend Sebright, Darwin commented "excellent observations of sickly offspring being cut off".

At the zoo on 28 March he had his first sight of an ape, and was impressed at the orang-utan's antics "just like a naughty child" when the keeper held back an apple. In his notes he wrote "Let man visit Ourang-outang in domestication, hear expressive whine, see its intelligence.... let him look at savage...naked, artless, not improving yet improvable & let him dare to boast of his proud preeminence." Here Darwin was drawing on his experience of the natives of Tierra del Fuego and daring to think that there was little gulf between man and animals despite the theological doctrine that only mankind possessed a soul.

Malthus and Natural Law

On 21 June 1838 Darwin was elected to the establishment Athenaeum Club, and it was here in August that he read a review of Auguste Comte's Positive Pholosophy which bolstered Darwin's ideas of natural laws, making him remark "What a magnificent view one can take of the world" with everything synchronised "by certain laws of harmony". Then in late September he began reading the new 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. Malthus had softened from the bleakness of the earlier editions, now allowing that the population crush could be mitigated by education, celibacy and emigration.

Already Radical crowds were demonstrating against the harsh imposition of Malthusian ideas in the Poor Laws, and a slump was resulting in mass emigration. Lyell was convinced that animals were also driven to spread their territory by overpopulation, but Darwin went further in applying to his search for the Creator's laws the Whig social thinking of struggle for survival with no hand-outs. He did broach the subject with Emma around the time that he proposed to her in November, and when she wrote expressing concern about his faith, his warm reply eased matters but this tension would remain. 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".

Developments

On 19 December 1838 as secretary of the Geological Society of London Darwin witnessed the vicious interrogation by Owen and his allies of Darwin's old tutor Robert Edmund Grant which ridiculed Grant's Lamarckian heresy, a reminder of establishment intolerance of materialist theories.

In 1839, once married and settled in smoky London, Darwin continued to look to the countryside for information and began a Questions & Experiments notebook with ideas that would have seemed bizarrely mundane to the "philosophical" scientists of the time. He printed Questions about the Breeding of Animals and sent them out to gentlemen farmers, asking for information on animal husbandry from their nurserymen and gamekeepers on how they crossed varieties or selected offspring. Of only three who responded, one simply found the questions too overwhelming to answer. He found agreement with the visiting Swiss botanist de Candolle who had first mooted the idea of "nature's war". However, when he tried explaining his theory to Hensleigh Wedgwood, his cousin "seemed to think it absurd... that (a) tiger springing an inch further would determine his preservation".

The publication in May of Darwin's Journal and Remarks (The Voyage of the Beagle) brought reviews accusing him of theorising rather than letting the facts speak for themselves. He turned his attention to a book on coral atolls.

In December as Emma's first pregnancy progressed, Charles fell ill and got little done during the following year. He did accept a position on the Council of the Geographical Society in May 1840. In 1841 he became able to work for short periods a couple of days a week, and produced a paper on stones and debris being carried by ice floes, but his condition did not improve. Having consulted his father he began looking for a house in the countryside to escape a city suffering from economic depression and civil unrest. Owen was one of the few scientific friends to still visit Darwin at this time, but Owen's opposition to any hint of Transmutation made Darwin keep quiet about his theories.

First writings on the theory

In January 1842 Darwin 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".

Illness was a continuing problem, and as his books on Coral Reefs and Fish reached print he and Emma left London on 18 May, visiting her parents at Maer then moving on to Shrewsbury on 15 June for rest and quiet. Here Darwin formulated a 35 page "Pencil Sketch" of his theory. This discussed farmers breeding animals, gave the analogy of overpopulation and competition leading to "Natural Selection" through the "war of nature" and the mechanism of descent. Every living thing was related in a branching pedigree, not ascending up a Lamarckian ladder, and this pedigree was the proper basis for classification. He thought it "derogatory" to argue that God had made every kind of parasite and worm on an individual whim, believing that everything resulted from grand laws that should "exalt our notion of the power of the omniscient Creator" and concluding that "From death, famine, rapine and the concealed war of nature we can see that the highest good, which we can conceive, the creation of the higher animals has directly come."

Essay

They returned on 18 July to a London seething with Chartist unrest, and Darwin copied and scribbled changes to his "Sketch" until it was almost illegible. He returned to house hunting and found a former parsonage in the rural hamlet of Downe, Kent at a good price. A general strike led to huge demonstrations all over London, but was crushed by troops by the time they moved. On 17 September 1842 the family moved into Down House. After a series of alterations Darwin settled in, and in 1843 returned to writing his Volcanic Islands. In May he began a (mostly geological) country diary he called The General Aspect. Asked by George Robert Waterhouse for advice on classification, he wrote of "descent from common stocks" and "members of the series, which have not become extinct", cautiously asking for the letter to be returned, but Waterhouse was influenced by Owen and in print attacked such heresies, setting his species in symbolic circles, not hereditary trees.

Darwin found a new friend, the botanist Joseph Dalton Hooker, and on 11 January 1844 wrote to him of Transmutation, describing this as being like confessing "a murder", hinting at Transmutation's association with radicals and riots. Hooker's reply was cautious but friendly, saying that there may have been "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 this subject."

Darwin worked up his "Sketch" into a 189 page "Essay" and in July entrusted the manuscript to the local schoolmaster to copy. He then wrote a difficult letter to be opened by his wife in the event of his death requesting that the essay be published posthumously. He started his Geological Observations on South America, and corresponded with Hooker about this, feeding in questions related to his secret "Essay". The copied "Essay", now 231 pages, was returned to him for corrections in September. Then one day he brought it to Emma and asked her to read it. She went through the pages, making notes in the margins pointing out unclear passages and showing where she disagreed.

Consolidation

In October 1844 Transmutation became a middle class talking point with the anonymous publication of Vestiges of the Natural History of Creation by Robert Chambers presenting Lamarckian views. It was a best-seller and while attacked by the established church and naturalists, was liked by many Quakers and Unitarians. Darwin was critical of its geology and zoology, but scorned the response which showed "the dogmatism of the pulpit". It paved the way for discussion, but emphasised the need for secure mastery of awkward facts.

Darwin continued to gather "trifling facts". The Revd. Leonard Jenyns who he'd learnt from at the University of Cambridge became a useful source, particularly on bird mortality. Darwin explained his interest in finding reason behind a "grand body of facts", writing "The general conclusion at which I have slowly been driven from a directly opposite conviction is that species are mutable & that allied species are co-descendants of common stocks. I know how much I open myself, to reproach, for such a conclusion, but I have at least honestly & deliberately come to it." Jenyns rebuffed this deviation from Creation and never accepted an offer of reading the "Essay".

Hooker became Darwin's mainstay in the search to find and explain anomalous facts, though Darwin was greatly disappointed in February 1845 when Hooker was invited to teach botany at Edinburgh. Others helping included Captain Beaufort of the Admiralty who invited Darwin to list any facts he wanted checking, for investigation by ship's surgeons (naturalists) when their ship in the appropriate part of the world.

In March Darwin followed his father's investment advice and became owner of a farmhouse and estate in Lincolnshire. The publisher John Murray got Darwin to divert his attention from South America to a revised second edition of his Journal and Remarks to which he added the latest information and interpretation, now seeing the Galápagos Archipelago as "a little world within itself" where "we seem to be brought somewhat near to that great fact – that mystery of mysteries – the first appearance of new beings on this earth". He dedicated the new edition to Lyell, but having been horrified by Lyell's Travels in North America which saw no harm in slavery, he added a last section cataloguing atrocities starting with the words "I thank God, I shall never again visit a slave country."

Correspondence with Hooker continued, and later in 1845 Darwin offered his "rough Sketch" for comments, but when Hooker and a group of young naturalists visited Down in December Hooker, having no formed opinion of his own, stuck to the assumption that species were immutable. In the following year potato blight brought famine which impinged on the Darwin's servants and workmen, and lead to overthrow of the Corn Laws. Despite his own illness recurring, Darwin pressed on with South America, having to jointly subsidise it with the publisher when the Treasury grant ran out, and it was completed by October 1846.

Barnacles

A single barnacle species was left to describe, and Darwin began dissecting with the assistance of Hooker who was now at Kew. To compare this with other species he borrowed specimens, and soon became involved in a much needed comprehensive study of these peculiar creatures which had recently been found to be crustaceans rather than molluscs. To Hooker such an exhaustive study might dampen Darwin's tendency to speculative theorising, and to Darwin it would establish his credentials.

Hooker paid frequent visits, and 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. Their debates continued, sometimes argumentatively, and Darwin felt devastated by Hooker's intention to set off on a survey voyage. Darwin overcame illness to attend the British Association for the Advancement of Science meeting at Oxford in May, to discuss the "Sketch" with Hooker. Others at the meeting, including Bishop Wilberforce, attacked Chambers, and Darwin dissociated himself from the error-ridden Vestiges. For the rest of the year Darwin suffered increasing health problems, with fiercely inflamed boils, then in November Hooker set off to India.

Between then 1858, when he would present his theory to the Linnean Society of London, Darwin wrote his masterpiece, modifying his theory in a number of ways as he wrote.