Darwin, Charles, 1809-1882
Charles Robert Darwin (February 12, 1809 – April 19, 1882) was an English naturalist whose revolutionary theory laid the foundation for both the modern theory of evolution and the principle of common descent by proposing natural selection as a mechanism. He published this proposal in 1859 in the book The Origin of Species, which remains his most famous work. A worldwide sea voyage aboard HMS Beagle and observations on the Galapagos Islands in particular provided inspiration and much of the data on which he based his theory.
A. Biography
i)Early life
ii)Journey on the Beagle
iii)Darwin shapes his theory
iv)First writings
v)Marriage and children
vi)The Origin of Species
vii)Later works and death
viii)Views on religion
ix)Legacy
x)Social Darwinism
B. Charles Darwin's views
on religionii)Journey on the Beagle
iii)Darwin shapes his theory
iv)First writings
v)Marriage and children
vi)The Origin of Species
vii)Later works and death
viii)Views on religion
ix)Legacy
x)Social Darwinism
i) Darwin's religious background
ii) Edinburgh — medical studies and Lamarckian evolution theory
iii) Cambridge — theology and geology
iv) Relevance
v) Darwin's views expressed in his writings
vi)The Lady Hope story
ii) Edinburgh — medical studies and Lamarckian evolution theory
iii) Cambridge — theology and geology
iv) Relevance
v) Darwin's views expressed in his writings
vi)The Lady Hope story
C.History of Darwinism
i) Science before Darwin
ii) The Origins of Darwinism
iii) Victorian Darwinism
iv) Post-Darwinian Developments
ii) The Origins of Darwinism
iii) Victorian Darwinism
iv) Post-Darwinian Developments
D. Darwin, Genes and Determinism
E. Darwin and Darwinism
A. Biography
Early life
Charles Darwin was born in Shrewsbury, Shropshire, England, on February 12, 1809 at the family home, The Mount House. He was the fifth of six children of Robert and Susannah Darwin (née Wedgwood), and the grandson of Erasmus Darwin, and of Josiah Wedgwood, a family of the Unitarian church. See also Darwin–Wedgwood family.
His mother died when he was only eight and the next year he became a boarder at the Shrewsbury School. After finishing school, Darwin went to Edinburgh University in 1825 to study medicine.
At Edinburgh his disgust at the anatomy lectures of professor Alexander Munro III and his revulsion at the brutality of surgery at the time led him to neglect his medical studies, but in his second year he became active in student societies for naturalists. In the Plinian society he became an avid student of Robert Edmund Grant, learning from Grant's enthusiasm for the theories of Lamarck and Charles' grandfather Erasmus about evolution by acquired characteristics. He joined Grant in pioneering investigations of the life cycle of marine animals on the shores of the Firth of Forth where Grant found evidence for homology, the radical theory that all animals had similar organs differing only in complexity. In March 1827 Darwin made a presentation to the Plinian society of his discovery that black spores often found in oyster shells were the eggs of a skate leech. Darwin also sat Robert Jameson's natural history course, learning about stratigraphic geology and getting to assist with the collections of the Museum of Edinburgh University, then one of the largest in Europe. At professor Robert Jameson's Wernerian Natural History Association Charles saw John James Audubon give a demonstration of his method of using wires to prop up birds to draw or paint them in natural positions.
His father, unhappy that his younger son would not become a physician and fearing that Charles would become a "ne'er do well", enrolled him at Christ's College, Cambridge in 1827 on a BA course to qualify as a clergyman. This was a sensible career move at a time when a "living" as an Anglican parson provided a comfortable income and when most naturalists in England were clergymen who saw it as part of their duties to explore the wonders of God's creation.
At Cambridge Charles preferred riding and shooting to studying, and along with his cousin William Darwin Fox became engrossed in the current craze for the (competitive) collecting of beetles. Fox introduced him for advice on this to the Revd. John Stevens Henslow, professor of botany, and Charles subsequently joined his natural history course. Henslow's outings were attended by 78 men including the Revd. William Whewell and Charles became the 'favourite pupil', known as "the man who walks with Henslow". When exams loomed Charles focused on his studies, becoming particularly enthused by the set texts by Paley which included the argument of divine design in nature. He got private tuition from Henslow whose subjects were maths and theology, and in his finals in January 1831 he shone in theology and scraped through in classics, maths and physics, coming 10th out of a pass list of 178.
Although he had gained his degree, residence requirements kept Darwin at Cambridge till June and following Henslow's example and advice he was in no rush to take holy orders. Inspired by Alexander von Humboldt's Personal Narrative he wanted to study natural history in the tropics and planned to visit Madeira with some class-mates upon graduation. Knowing the need for geological skills, Henslow introduced Charles to the great geologist the Revd. Adam Sedgwick and Darwin joined his course, then that summer worked with him at mapping strata in Wales.
Darwin was surveying strata in Wales on his own when he received a message that his intended companion had died, dashing his plans to visit Madeira, but on his return home he received another letter. Henslow had recommended Darwin for the position of gentleman's companion to Robert FitzRoy, the captain of HMS Beagle which was departing in December on a two-year expedition to chart the coastline of South America and would give him opportunities as a naturalist. His father objected to the voyage, thinking it a waste of his son's time, but was eventually persuaded by Josiah Wedgwood to agree to Charles going and to pay for his son's expedition which eventually stretched to five years.
Journey on the Beagle
Darwin's work during the Beagle expedition allowed him to study both the geological properties of continents and isles and a multitude of living organisms and fossils. He collected an enormous number of specimens new to science in a very methodical way, and his specimens sent back to the University of Cambridge were by themselves a significant contribution to science, and made him one of the precursors of ecology. No other collector has rivalled his work since. He also took many detailed notes on everything he observed, which would form the basis for his later work. Others on board, including FitzRoy, also made significant collections which were deposited in the British Museum by the Admiralty.
Before they left England FitzRoy had given Darwin a copy of the first volume of Charles Lyell's Principles of Geology which explained features as the outcome of a gradual process over huge periods of time, and Darwin wrote home that he was 'seeing' land-forms as if he had the eyes of Lyell. During his voyage, he visited the Cape Verde Archipelago, the Falkland Islands, the South American coast, the Galapagos Islands, New Zealand and Australia, meeting native peoples, seeing natural wonders, and above all, collecting considerable quantities of specimens which were sent back at intervals during the voyage. Quite apart from the wealth of detailed biological accounts they give, Darwin's published accounts also provide us with social, political, and anthropological insights into the areas he visited. For instance his account of how the Gaucho of Argentina lived is particularly interesting. Further, the journals reveal him to be a very active and intrepid adventurer who thought nothing of embarking on 200 mile journeys across dangerous territories, in marked contrast to the better known image of an elderly country gentleman.
While in South America, he contracted Chagas' disease from insect bites. Although not fatal, it recurred several times during his life, and prevented him from being particularly active.
On the Beagle's return on October 2, 1836, Darwin was invited by FitzRoy to contribute the natural history section to the captain's account of the Beagle's voyage, and used his field notes as the basis of the third volume of this account, published in 1839. Darwin's Journal and Remarks was very popular and later that year was published on its own becoming the best-seller nowadays known as "The Voyage of the Beagle", establishing Darwin as an author.
Darwin shapes his theory
After returning from the voyage, Darwin analysed the specimens he collected, and considered similarities between fossils and living species within the same geographic area. In particular, every island in the Galapagos Archipelago had its own kind of tortoises and birds that were all slightly different in appearance, favoured food etc., but otherwise similar.
In the spring of 1837 ornithologists at the British Museum informed Darwin that the several very different species of birds he had taken in the Galapagos were all finches, and from FitzRoy's collection he was able to relate the finches to separate islands. This, coupled with a re-reading of Thomas Malthus' 1798 essay on populations, triggered a chain of thought that would culminate in the theory of evolution by natural and sexual selection. He developed the hypothesis that, for example, all the different turtles had originated from a single turtle species, and had adapted to life on the different islands in different ways.
Based on these thoughts, he formulated his ideas about the changes and developments of species in his Notebook on the Transmutation of Species, which was in accordance with Lyell's Principles of Geology involving gradual change over a long time, and Thomas Malthus' Essay on the Principle of Population which stated that the size of a population is limited by the food resources available. Realizing the potential of this understanding, Darwin undertook extensive experiments with pigeons and plants, and extensive consultation with pig breeders and other animal husbanders, in an attempt to discover holes in the hypothesis. He took his time with careful research until he had enough evidence, knowing that a great deal of opposition would likely erupt when he presented his theory.
First writings
Following his account of The Voyage of the Beagle, Darwin's Zoology of the Voyage of H.M.S. Beagle was published between 1839 and 1843 in five volumes. Darwin published scientific treatises, including an explanation for the life-cycle of coral atolls in the South Pacific published in 1842.
In 1842, Darwin formulated a short "Pencil Sketch" of his theory and by 1844 had written a 240 page "Essay" which provides an expanded version of his early ideas on natural selection. Between 1844 and 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.
Marriage and children
Darwin married his cousin Emma Wedgwood in 1839. After living for a number of years in London, the couple eventually moved to Down House, in Downe, Kent (which is now open to public visits, south of Orpington). The Darwins had ten children, three of whom died early. Many of these and their grandchildren would later achieve notability themselves (see Darwin–Wedgwood family)
William Erasmus Darwin (27
December 1839 – 1914)
Anne Elizabeth Darwin (2 March 1841 – 22 April 1851)
Mary Eleanor Darwin (23 September 1842 – 16 October 1842)
Henrietta Emma "Etty" Darwin (25 September 1843 – 1929)
George Howard Darwin (9 July 1845 – 7 December 1912)
Elizabeth "Bessy" Darwin (8 July 1847 – 1926)
Francis Darwin (16 August 1848 – 19 September 1925)
Leonard Darwin (15 January 1850 – 26 March 1943)
Horace Darwin (13 May 1851 – 29 September 1928)
Charles Waring Darwin (6 December 1856 – 28 June 1858)
Anne Elizabeth Darwin (2 March 1841 – 22 April 1851)
Mary Eleanor Darwin (23 September 1842 – 16 October 1842)
Henrietta Emma "Etty" Darwin (25 September 1843 – 1929)
George Howard Darwin (9 July 1845 – 7 December 1912)
Elizabeth "Bessy" Darwin (8 July 1847 – 1926)
Francis Darwin (16 August 1848 – 19 September 1925)
Leonard Darwin (15 January 1850 – 26 March 1943)
Horace Darwin (13 May 1851 – 29 September 1928)
Charles Waring Darwin (6 December 1856 – 28 June 1858)
The Origin of Species
Announcement of theory
Darwin's work brought him a correspondence relationship with Alfred Russel Wallace, working in the islands of the South Pacific and Indonesia. Wallace had been one of Darwin's numerous providers of natural history specimens, and was considerably lower in social status than Darwin himself. On June 18th 1858, Wallace sought Darwin's ideas on a theory Wallace had developed which almost exactly mirrored Darwin's own work. Darwin was himself horrified at the prospects of being scooped, but also felt bound to respect Wallace's claim to priority. Seeking advice from his scientific friends, he was encouraged to announce his theory along with Wallace's contribution, and to establish that he had in fact started developing the theory ten years before Wallace did. On July 1, 1858, Darwin's announcement of his theory was read to the Linnean Society, in London, jointly with Wallace's paper. Neither men were present at the reading, Darwin was at home with his dying son, and Wallace was in the Far East somewhere. The paper was entitled On the Tendency of Species to form Varieties; and on the Perpetuation of Varieties and Species by Natural Means of Selection. Fortunately for Darwin, Wallace was satisfied with the arrangement: though he would always be second-string to Darwin (his role reduced to that of catalyst), to be linked to a well-respected naturalist of high social standing like Darwin was still a fantastic career opportunity, perhaps more than he could have accomplished himself in the tight-knit circle of Victorian-era science.
The initial announcement of the theory garnered little immediate attention. It was mentioned briefly in a few small reviews but did not yet command much further thought, and was not yet fully distinguishable to most people from other varieties of evolutionary thought. For the next thirteen months, Darwin would labour to produce what was originally to be an abstract of his "big book on species". Receiving constant promotion and encouragement from his scientific friends, Darwin finally finished On the Origin of Species by Means of Natural Selection and arranged to have it published. Through his network of social connections and correspondents, Darwin's book was given a great deal of initial attention, marketed by his scientifically respectable friends as being a worthy contribution to scientific thought, and with reviews placed in prominent periodicals. As attention and controversy gathered, the book was translated into numerous languages and went through a number of reprints, becoming a staple scientific text accessible to a newly curious middle class. It would prove to be the most controversial and discussed scientific book ever written.
Reaction
Caricature of Darwin as an ape in the Hornet magazine
It provoked an outraged response from the Church of England. At a meeting of the British Association for the Advancement of Science in Oxford, 'Soapy Sam' Wilberforce, the Bishop of Oxford, and Robert FitzRoy (the Captain of HMS Beagle) argued against Darwin, and Thomas Huxley established himself as "Darwin's bulldog" – the fiercest defender of evolutionary theory on the Victorian stage. On being asked by Wilberforce, whether he was descended from monkeys on his grandfather's side or his grandmother's side, Huxley, recognizing his opportunity, apparently muttered to himself: "The Lord has delivered him into my hands", and then replied that he "would rather be descended from an ape than from a cultivated man who used his gifts of culture and eloquence in the service of prejudice and falsehood" (several alternative versions of this supposed quote exist, see Wilberforce and Huxley:
A Legendary Encounter (http://users.ox.ac.uk/~jrlucas/legend.html)).
The story spread around the country: Huxley had said he would rather be an ape than a Bishop.
Darwin himself did not personally defend his theories in public, though he watched the ongoing debates eagerly. He was constantly in ill health, and preferred to garnish support by means of his letters and correspondence. A core circle of scientific friends–Huxley, Charles Lyell, Joseph Dalton Hooker, and Asa Gray–actively pushed his work onto the fore of the scientific and public stage, and defended him against his many mounting critics. Unexpectedly to Darwin, his theory became not only a key scientific controversy of the era, but was also resonated with many anti-Victorian sentiments at the time, becoming a key fixture of popular culture of the period (and beyond).
Later works and death
In several of his later books The Variation of Animals and Plants Under Domestication (1868), The Descent of Man and Selection in Relation to Sex (1871) and The Expression of Emotions in Animals and Man (1872), Darwin expanded on many topics introduced in Origin of Species. The Descent of Man, in particular, aroused even greater argument since it theorized that humanity was descended from apes. Forever afterward, Darwin would be characterized as "the monkey man", and cartoons often depicted him as part ape.
Darwin's life work provoked continuing discussions in the scientific community, and established more than anything else that "evolution" itself had occurred: not necessarily that it was by natural or sexual selection (this particular recognition would not become fully standard until the rediscovery of Gregor Mendel's work in the early 20th century). He became a member of the Royal Society of London in 1839 (on the basis of his collecting during his voyages) and of the French Academy of Sciences (l'Académie des Sciences) in 1878.
Darwin died in Downe, Kent, England, on 19 April 1882 and was given a state funeral. William Spottiswoode, President of the Royal Society arranged for Darwin to be buried in Westminster Abbey near Isaac Newton, despite Darwin's wishes that he be buried in Downe.
Views on religion
Charles Darwin came from a Non-conformist background, then studied Anglican theology with the aim of becoming a clergyman, at a time of religious and political turmoil in England. Though he recalled that "Whilst on board the Beagle I was quite orthodox" he later struggled with faith and became increasingly agnostic.
A popular Christian urban legend falsely claims (variously) that he "converted" to Christianity on his deathbed
Legacy
Charles Darwin's theory of evolution based upon natural selection changed the thinking of countless fields of study from biology to anthropology. His work was extremely controversial by the time he published it and many during his time didn't take it seriously. Darwin's theory of evolution was a significant blow to creationism and notions of intelligent design prevalent among 19th century Europe.
As a humorous celebration of the theory of evolution, the annual Darwin Award is bestowed on individuals who "aid the process of evolution by demonstrating their unfitness" through fatally stupid actions.
In Australia's Northern Territory, the capital city (originally Palmerston) was renamed Darwin to commemorate the author's 1839 visit there, and the territory now also boasts Charles Darwin University and Charles Darwin National Park.
Darwin was given particular recognition in 2000 when his image appeared on the Bank of England ten pound note, replacing Charles Dickens. His impressive and supposedly hard-to-forge beard was reportedly a contributing factor in this choice.
Darwin came fourth in the 100 Greatest Britons poll sponsored by the BBC and voted for by the public.
Social Darwinism
A version of natural selection was also applied to human society (politics, economics, etc.). The most famous of these doctrines is Social Darwinism, a term that first appeared in about 1900, where the rule of the strong is justified by claims that it merely reproduces in society Nature's rule that the fittest survive. It is clear that Darwin never advocated this extension of Herbert Spencer's philosophy. He reacted strongly against the slavery he saw in South America, causing a dramatic though brief dispute with FitzRoy who thought slavery justifiable, and while Darwin contrasted the miserable condition of savages with civilised society, he was clear that the difference was due to learning and culture rather than being innate. He evinced great sympathy for enslaved or oppressed people and looked forward to a day when his 19th century concept of knowledge and enlightenment would bring civilization to all men.
B. Charles Darwin's views on religion
These have been the subject of much interest. His work was pivotal in the development of evolution theory which some argue helps show that God is unnecessary, while others feel that attacking Darwin and restricting teaching of evolution helps to evangelise their faith.Darwin's religious background
Charles Darwin was born during the Napoleonic Wars and grew up in their aftermath, a conservative time when Tory dominated government closely associated with the established High Church of England repressed Radicalism, but when family memories recalled the 18th century Enlightenment and a multitude of Non-conformist churches held differing interpretations of Christianity. His Whig supporting extended family of Darwins and Wedgwoods was strongly Unitarian, though one of his grandfathers, Erasmus Darwin, was a freethinker even less restrained by religious dogma. While his parents were open enough to changing social pressures to have Charles baptised in the Church of England, his pious mother took the children to the Unitarian chapel. After her death when he was only eight he became a boarder at the (Church of England) Shrewsbury School public school.
Edinburgh — medical studies and Lamarckian evolution theory
The two universities in England, Oxford and Cambridge, were under the Church of England and required students to sign the Thirty-nine Articles of the Anglican faith, so many English Non-conformists sent their children to the Scottish universities which had a better reputation in fields like medicine. Charles initially attended the University of Edinburgh, and while he was put off medicine because of the gore and the poor quality of professors corruptly appointed by the Tory town council, in his second year he became active in the Plinian student society which was a hotbed of Radical naturalists. Here he met Robert Edmund Grant, joining him on field trips and learning from Grant's enthusiasm for Lamarck's theory of evolution by acquired characteristics.
Natural history had grown from the idea that the different kinds of plants and animals showed the wonder of God's creation, making their study and cataloguing into species worthwhile. In Darwin's day it was common for clergymen to be naturalists, but scientific findings had already opened up ideas on creation and evolution. The established churches (of England and Scotland) and the English universities remained insistent that species were miraculously created and man was distinct from the "lower orders", but the Unitarian church rejected this dogma and even proclaimed that the human mind was subject to physical law. Erasmus Darwin went further and his Zoönomia asks ..would it be too bold to imagine that all warm-blooded animals have arisen from one living filament, which the great First Cause endued with animality....possessing the faculty of continuing to improve by its own inherent activity, and of delivering down these improvements by generation to its posterity, world without end!, anticipating Lamarck's thesis. Many were outraged at such sacrilege, and after his death in 1802 he was attacked for doubting the Bible and a story was started that he had called for Jesus on his deathbed. Charles would thus have had a perception of Christianity comfortable with ideas of evolution while being very aware of the outrage of the establishment and the patriotic mob.
Cambridge — theology and geology
While Charles' father Robert had followed his own father Erasmus in medical practice and freethinking, he kept the latter quiet. When Charles proved unable to persevere at medical studies an option was for his father to purchase at auction a country parish "living" as an Anglican parson. Charles overcame his initial uncertainty by reading divinity books and then followed his father's bidding by enrolling at Christ's College, Cambridge for the required BA course.
He joined the natural history course of the Revd. John Stevens Henslow who gave him tuition in theology, and Charles became particularly interested in the writings of the Revd. William Paley. Paley's Evidences of Christianity and Moral and Political Philosophy were set texts, and after doing well in his theology finals Charles read Paley's Natural Theology which saw a rational proof of God's existence in the complexity of living beings exquisitely fitted to their places in a happy world, proving their design by a Creator. While this was a odds with the ideas of Grant and Erasmus Darwin, it convinced Charles and encouraged his interest in science. During this time Cambridge was briefly visited by the Radicals Richard Carlile and the Revd. Robert Taylor on an "infidel home missionary tour", causing a stir before being banned, and Taylor would be remembered by Charles as "the Devil's Chaplain", a warning example of an outcast from society who had challenged Christianity and had been imprisoned for blasphemy.
Before leaving Cambridge, Charles studied geology with the Revd. Adam Sedgwick, then got the opportunity to join a survey expedition as gentleman's companion to captain Robert FitzRoy on HMS Beagle. Before they left England FitzRoy gave Darwin a copy of the first volume of Charles Lyell's Principles of Geology.
The developing science of geological strata and the finding of extinct fossils appeared to contradict the Biblical account of Noah's flood, but this was reconciled by the generally accepted theory of Catastrophism postulating a series of catastrophic floods each followed by the creation of new species ex nihilo. Lyell's book explained features as the outcome of a gradual process over huge periods of time, though he also thought that extinctions were explained by a "succession of deaths" with new species then being created. Darwin later wrote home that he was 'seeing' land-forms as if he had the eyes of Lyell. FitzRoy evidently shared this view at the time, but on the return of the Beagle he wrote a section for his account of the voyage recanting this and earnestly explaining his renewed commitment to a literal reading of the Bible, with rock layers high in the mountains containing sea shells interpreted as proof of Noah's Flood and ideas of the six days of creation extending over aeons dismissed because the grass, herbs and trees would have died out during the long nights. In contrast, Darwin by then had developed a convincing new theory on the formation of coral atolls which supported Lyell's arguments.
Charles Darwin then went on to develop his theory On the Origin of Species by Means of Natural Selection and to increasingly doubt the validity of a literal reading of the Bible.
Relevance
The theory of evolution tends to oppose one of the arguments for belief in supernatural creation by a god(s), by providing an explanation for the appearance of the organized complexity and diversity of life on Earth. (See argument from evolution.) Because of this, many from both sides of the atheism/theism debate would like to think that Charles Darwin shared their position, even though following Darwin would be an appeal to authority, which is generally considered fallacious. Darwin contributed little, if any, to metaphysics and there have been advances in that subject since then (see philosophy of science, rationalism), so Darwin's authority is questionable. Darwin's religious views are also irrelevant to the accuracy of the theory of evolution by means of natural selection which stands or falls on its evidence, and not who first published it. The theory of evolution as the central unifying paradigm of biology is not doubted by the scientific community, but is fiercely opposed by religious sects in some countries, particularly the USA, who promote creationism as having equal or greater validity.
Darwin's views expressed in his writings
From: The Descent of Man
In the introduction of The Descent of Man (1871), Darwin wrote:
"Ignorance more frequently begets confidence than does knowledge: it is those who know little, and not those who know much, who so positively assert that this or that problem will never be solved by science."
Later on in the book he dismisses an argument for religion being innate:
"Belief in God- Religion.- There is no evidence that man was aboriginally endowed with the ennobling belief in the existence of an Omnipotent God. On the contrary there is ample evidence, derived not from hasty travellers, but from men who have long resided with savages, that numerous races have existed, and still exist, who have no idea of one or more gods, and who have no words in their languages to express such an idea. The question is of course wholly distinct from that higher one, whether there exists a Creator and Ruler of the universe; and this has been answered in the affirmative by some of the highest intellects that have ever existed."
"The belief in God has often been advanced as not only the greatest, but the most complete of all the distinctions between man and the lower animals. It is however impossible, as we have seen, to maintain that this belief is innate or instinctive in man. On the other hand a belief in all-pervading spiritual agencies seems to be universal; and apparently follows from a considerable advance in man's reason, and from a still greater advance in his faculties of imagination, curiosity and wonder. I am aware that the assumed instinctive belief in God has been used by many persons as an argument for His existence. But this is a rash argument, as we should thus be compelled to believe in the existence of many cruel and malignant spirits, only a little more powerful than man; for the belief in them is far more general than in a beneficent Deity. The idea of a universal and beneficent Creator does not seem to arise in the mind of man, until he has been elevated by long-continued culture."
From: a letter in 1860
In a letter to his collaborator Asa Gray Darwin expressed his doubts about the existence of god:
"With respect to the theological view of the question: This is always painful to me. I am bewildered. I had no intention to write atheistically, but I own that I cannot see as plainly as others do, and as I should wish to do, evidence of design and beneficence on all sides of us. There seems to me too much misery in the world. I cannot persuade myself that a beneficent and omnipotent God would have designedly created the Ichneumonidae with the express intention of their feeding within the living bodies of caterpillars or that a cat should play with mice... On the other hand, I cannot anyhow be contented to view this wonderful universe, and especially the nature of man, and to conclude that everything is the result of brute force. I am inclined to look at everything as resulting from designed laws, with the details, whether good or bad, left to the working out of what we may call chance."
From: a letter in 1873
In a letter to a correspondent at the University of Utrecht in 1873, Darwin clearly expresses agnosticism:
"I may say that the impossibility of conceiving that this grand and wondrous universe, with our conscious selves, arose through chance, seems to me the chief argument for the existence of God; but whether this is an argument of real value, I have never been able to decide. I am aware that if we admit a first cause, the mind still craves to know whence it came from and how it arose. Nor can I overlook the difficulty from the immense amount of suffering through the world. I am, also, induced to defer to a certain extent to the judgment of many able men who have fully believed in God; but here again I see how poor an argument this is. The safest conclusion seems to me to be that the whole subject is beyond the scope of man's intellect; but man can do his duty."
From: 1958 Autobiography
Darwin's own struggle with faith got sharper the older he became, and his posthumously-published autobiography contained quotes about Christianity that were omitted by Darwin's wife Emma and his son Francis because they were deemed dangerous for Charles Darwin's reputation. Only in 1958 Darwin's granddaughter Nora Barlow published a revised version which contained the omissions. This included statements such as:
"Whilst on board the Beagle (October 1836-January 1839) I was quite orthodox, and I remember being heartily laughed at by several of the officers (though themselves orthodox) for quoting the Bible as an unanswerable authority on some point of morality. I suppose it was the novelty of the argument that amused them. But I had gradually come, by this time, to see that the Old Testament; from its manifestly false history of the world, with the Tower of Babel, the rainbow as a sign, etc., etc., and from its attributing to God the feelings of a revengeful tyrant, was no more to be trusted than the sacred books of the Hindoos, or the beliefs of any barbarian." (Charles Darwin: The Autobiography of Charles Darwin with original omissions restored. New York, Norton, 1969. p.85) (note that the rainbow as a sign of the covenant implies that the physics of light discovered by Francis Bacon and Isaac Newton did not apply before the Biblical flood)
"By further reflecting that the clearest evidence would be requisite to make any sane man believe in the miracles by which Christianity is supported, --that the more we know of the fixed laws of nature the more incredible, do miracles become, --that the men at that time were ignorant and credulous to a degree almost incomprehensible by us, --that the Gospels cannot be proved to have been written simultaneously with the events, --that they differ in many important details, far too important as it seemed to me to be admitted as the usual inaccuracies of eyewitness; --by such reflections as these, which I give not as having the least novelty or value, but as they influenced me, I gradually came to disbelieve in Christianity as a divine revelation. The fact that many false religions have spread over large portions of the earth like wild-fire had some weight with me. Beautiful as is the morality of the New Testament, it can hardly be denied that its perfection depends in part on the interpretation which we now put on metaphors and allegories." (p.86)
"Thus disbelief crept over me at a very slow rate, but at last was complete. The rate was so slow that I felt no distress, and have never since doubted even for a single second that my conclusion was correct." (p.87) "I can indeed hardly see how anyone ought to wish Christianity to be true; for if so the plain language of the text seems to show that the men who do not believe, and this would include my Father, Brother and almost all my best friends, will be everlastingly punished. And this is a damnable doctrine." (p. 87) "The old argument of design in nature, as given by Paley, which formerly seemed to me so conclusive, fails, now that the law of natural selection had been discovered. We can no longer argue that, for instance, the beautiful hinge of a bivalve shell must have been made by an intelligent being, like the hinge of a door by man. There seems to be no more design in the variability of organic beings and in the action of natural selection, than in the course which the wind blows. Everything in nature is the result of fixed laws." (p.87)
"At the present day (ca. 1872) the most usual argument for the existence of an intelligent God is drawn from the deep inward conviction and feelings which are experienced by most persons. But it cannot be doubted that Hindoos, Mahomadans and others might argue in the same manner and with equal force in favor of the existence of one God, or of many Gods, or as with the Buddists of no God...This argument would be a valid one if all men of all races had the same inward conviction of the existence of one God: but we know that this is very far from being the case. Therefore I cannot see that such inward convictions and feelings are of any weight as evidence of what really exists." (p.91)
"Nor must we overlook the probability of the constant inculcation in a belief in God on the minds of children producing so strong and perhaps as inherited effect on their brains not yet fully developed, that it would be as difficult for them to throw off their belief in God, as for a monkey to throw off its instinctive fear and hatred of a snake." (p.93)
The Lady Hope story
It has been falsely claimed that Charles Darwin underwent a deathbed conversion to Christianity. Beyond being a common myth frequently applied to famous non-believers including Darwin's grandfather Erasmus, the claim can be dismissed by his never having left the church. This claim is discussed in The Survival of Charles Darwin: A Biography of a Man and an Idea, by Ronald W. Clark (Weidenfeld & Nicholson 1985), p. 199:
"Shortly after his death, Lady Hope addressed a gathering of young men and women at the educational establishment founded by the evangelist Dwight L. Moody at Northfield, Massachusetts. She had, she maintained, visited Darwin on his deathbed. He had been reading the Epistle to the Hebrews, had asked for the local Sunday school to sing in a summerhouse on the grounds, and had confessed: 'How I wish I had not expressed my theory of evolution as I have done.' He went on, she said, to say that he would like her to gather a congregation since he 'would like to speak to them of Christ Jesus and His salvation, being in a state where he was eagerly savouring the heavenly anticipation of bliss.'
"With Moody's encouragement, Lady Hope's story was printed in the Boston Watchman Examiner. The story spread, and the claims were republished as late as October 1955 in the Reformation Review and in the Monthly Record of the Free Church of Scotland in February 1957. These attempts to fudge Darwin's story had already been exposed for what they were, first by his daughter Henrietta after they had been revived in 1922. 'I was present at his deathbed,' she wrote in the Christian for February 23, 1922. 'Lady Hope was not present during his last illness, or any illness. I believe he never even saw her, but in any case she had no influence over him in any department of thought or belief. He never recanted any of his scientific views, either then or earlier. We think the story of his conversion was fabricated in the U.S.A.... The whole story has no foundation whatever.'" (Ellipsis original)
C. History of Darwinism
By: Peter J. Bowler is
Professor of History and Philosophy of Science at the Queen's
University of Belfast.
‘Why do we remember Charles Darwin? There are two reasons for celebrating the theory he proposed in his Origin of Species (1859), although they are not connected in the way a modern scientist might expect. Darwin persuaded Victorian scientists (and almost everyone else) to take evolution seriously. He also discovered what we now accept as the best explanation of how evolution works, the mechanism of natural selection. But historians know that the Victorians didn't welcome evolutionism because they thought Darwin had got the right explanation. In fact the selection theory was rejected by most scientists for 50 years after Darwin published, and only became widely accepted in the early twentieth century.
So why did the Victorians convert to evolutionism, and what happened in the twentieth century to make natural selection seem more plausible? We can explain these developments at two levels, scientific and cultural. there are scientific arguments for evolution that don't depend on natural selection, and there were major scientific developments in the post-Darwinian period (e.g. the emergence of genetics). But there were also cultural developments that made first evolution and then natural selection acceptable to a wider range of people.
Science before Darwin
Darwin and Genesis
Darwin himself didn't have to fight a battle over the literal interpretation of the Genesis creation story. the geologists had shown that a recent creation for the earth was implausible long before the Origin was published. High profile public opposition based on a return to Genesis only began in the 1920s, especially in America. It was in 1925 that John Thomas Scopes was put on trial in Dayton, Tennessee for teaching evolution. the "Monkey trial" was ridiculed by scientists and in the liberal press, but marked the start of a Fundamentalist backlash against evolutionism that still continues.
Evolution before Darwin.
The basic idea of evolution had been suggested by several writers, including Darwin's own grandfather, Erasmus Darwin, and by J. B. Lamarck. Lamarck proposed a mechanism known as the inheritance of acquired characteristics which even Darwin accepted. This supposes that characters acquired by an individual's efforts (e.g. the weightlifter's big muscles) are transmitted to the next generation. On this model, the giraffe's long neck is a product of thousands of generations of animals stretching up to reach the leaves of trees. Lamarckism was widely debated, but the theory was high-jacked in the 1820s (just as Darwin was beginning his career) by radicals and materialists, and was rejected by a scientific community still dominated by conservative thinkers.
In 1844 the Edinburgh writer Robert Chambers published his Vestiges of Creation in an attempt to convince the middle classes that progressive evolution is God's plan of creation unfolding through geological time. He saw social progress as the continuation of natural progress. Chambers' science was implausible, but Darwin eventually gave his political agenda a more scientific foundation and paved the way for wider acceptance of evolution.
The Origins of Darwinism
Darwin was converted to evolutionism by the results of his voyage on H.M.S. Beagle (1831-36) several years before he discovered the principle of natural selection. there were several key scientific influences on his thinking:
Geology Charles Lyell's uniformitarian geology suggested that changes on the earth's surface were slow and gradual, implying gradual changes in species adapting to new environments.
Natural theology the clergyman William Paley claimed that adaptation revealed design by God, prompting Darwin to focus on adaptation as a natural process.
Biogeography the Beagle voyage, especially the visit to the Galapagos islands, showed Darwin that isolated populations adapt and evolve in different directions. Several species of finch had evolved on different islands, each with a beak adapted to a different way of feeding. Unless each tiny species was the product of a miracle, populations separated by isolation on the islands had each adapted in their own way. This insight taught Darwin that evolution is a branching process, not the ascent of a ladder of progress toward humanity.
Artificial Selection the animal breeders showed Darwin that populations exhibit random variation from which useful characters can be selected.
Social Metaphors Thomas Malthus' principle of population-expansion convinced him there must be a "struggle for existence" in which the fittest variants survive and breed. Natural selection or the "survival of the fittest" offered a new explanation of how the giraffe got its long neck: in each generation those individuals born with longer than average necks had survived and reproduced. Note the social input here -- Malthus' theory was a product of free-enterprise capitalism, based on the assumption that society consists of competing individuals. Darwin showed that individual struggle will generate progress (or at least better adaptation). If he could put an optimistic spin on Malthus, this idea of "progress through struggle" would be just what the middle classes were looking for in their search for an ideology stressing the benefits of effort and initiative.
Wallace, the Co-discoverer Darwin was eventually persuaded to publish his idea when Alfred Russel Wallace developed a similar idea independently. But Wallace was twenty years behind Darwin, and his thinking on evolution never overlapped completely with Darwin's.
Victorian Darwinism
There was much initial opposition to the Origin from religious thinkers and from some scientists. But it was soon overcome, and by the 1870s most educated people accepted evolutionism. Why was there such a rapid change in scientific and public opinion?
Darwinism in Science In science, the general idea of evolution helped to explain a number of facts, including the relationships between species, their geographical distribution, and the trends shown in the fossil record. But what about natural selection? This was more problematic -- most scientists thought it was an interesting new idea but they were not convinced that it was the main driving force. Even T. H. Huxley -- known as "Darwin's bulldog" -- didn't accept natural selection. What modern biologists see as Darwin's most original insight was ignored by many early evolutionists. the theories they did accept -- including Lamarckism -- tell us a lot about the wider public reaction to Darwin. Most scientists, like most ordinary people, wanted evolution to be a purposeful, progressive force -- mere "trial and error" was not enough.
Evolution and Humankind Evolution was accepted as part of the ideology of progress. Religious opposition was strong at first, especially over the presumed link between humans and an animal ancestry. Asked to decide whether man was an ape or an angel, the Conservative politician Disraeli declared "I am on the side of the angels." But this level of opposition soon died down (until revived in the America of the 1920s). Evolution was accepted by the middle classes because it was seen as a progressive driving force in nature and society. the human race, as the highest product of evolution, was now at the cutting edge of progress toward higher things.
Social Darwinism But what about the "struggle for existence," with its apparently harsh implications? the Victorians welcomed Darwin's emphasis on struggle because they saw it as the stimulus to individual and racial progress -- this is "social Darwinism." the "invisible hand" which economists saw coordinating individual selfishness for the benefit of society could now be seen as generating an advance toward higher things. But it was not just a question of struggle eliminating the unfit. Many scientists and social thinkers were Lamarckians, including Herbert Spencer, the philosopher who coined the term "survival of the fittest" -- widely regarded as the greatest social Darwinist. Struggle forced individuals to improve themselves as well as weeding out the few totally unfit to survive, a view that many would see reincarnated in modern Thatcherism. the original social Darwinism was as much Lamarckism as Darwinism.
Darwinism and Race the same point can be made about those who applied Darwinism at the level of race. Natural selection was seen as merely a negative process weeding out the less successful forms produced by a purposeful upward trend. the German Darwinist Ernst Haeckel welcomed the subordination of "less advanced" races, which he saw as relics of earlier stages in the advance from the apes, preserving a child-like mentality. His ideas have been linked to the subsequent emergence of Nazism, and there can be no doubt that evolutionism offered many opportunities for those who wished to see the white race as the pinnacle of progress. Yet Haeckel adopted a Lamarckian view of the origin of races, while the Nazis were uncomfortable with the evolutionary view of human origins precisely because it proclaimed a common origin for all races. they wanted no blood relationship between Aryans and the inferior types. Evolutionism was widely applied to develop an ideology of struggle, but Darwinism as we know it today was only one component of Victorian -- and later -- right wing values.
Post-Darwinian Developments
The early twentieth century saw a backlash against Victorian Darwinism, although many aspects of the ideology of progress were adapted to the modern scientific and social environment. Developments in science have focussed attention on heredity and brought the theory of natural selection to the fore. But outside science there has been a polarization of views, especially on the question of human nature, some social thinkers welcoming the new Darwinism while others reject it.
Evolution without Darwin the most extreme reaction against Darwinism is the Fundamentalist return to the Genesis creation story. But some evolutionists reject the Victorian emphasis on struggle. Many early twentieth-century thinkers insisted that the Victorians had been blinded by the ideology of competition. Nature was not dominated by struggle, and progressed by developing increasing levels of cooperation. the author Samuel Butler dismissed Darwinsm as a "nightmare of waste and death," while the playwrite Bernard Shaw wrote that if the selection theory were true "only fools and rascals could bear to live." their revulsion is shared by many modern opponents of the selection theory who find its emphasis on trial and error impossible to square with the development of purposeful structures. Butler and Shaw both saw Lamarckism as the most plausible alternative -- but in the 1920s Lamarckism was eliminated from science by modern genetics.
The Rise of Genetics Darwin's theory was surprisingly modern except in his ideas about variation and heredity. the notion of the unit gene was popularized soon after 1900 and showed that characters are inherited as undiluted units. Lamarckism was discredited because the genes cannot be influenced by the body carrying them. After some controversy, it was realized that genetic mutation provided a new explanation of the random variation that Darwin saw in every population. With Lamarckism gone, the genetical theory of natural selection emerged in the 1930s and 40s, explaining adaptive evolution in terms of the changing genetic composition of populations. Many biologists now regard the synthesis of Darwinism and genetics as the only plausible explanation of evolution.
Genetic Determinism the development of genetics coincided with a strongly articulated social policy based on the view that heredity determines human characters. In the early twentieth century, many countries (not just Nazi Germany) had policies to restrict the breeding of the "unfit," often by compulsory sterilization. Artificial selection replaced natural selection in the human population -- the social policy known as eugenics. But who decides which characters are desirable? After the excesses of the Nazi regime, eugenics went underground, but our modern fascination with genes as the determinants of human characters may be reintroducing it through the back door.
Socio-biology the most controversial aspect of modern Darwinism links the genetic determination of human character to natural selection as the explanation of behavioural instincts. Richard Dawkins and others insist that natural selection explains not only the development of animals species, but also the development of the human mind. Socio-biology, based on what Dawkins calls the "selfish gene", accounts for animal behaviour in terms of genetically programmed instincts shaped by natural selection. Many Darwinians insist that this programme can be applied to human behaviour: we are what our genes determine us to be. Most social scientists resist this, arguing that the human brain (admittedly developed by evolution) has acquired a capacity to learn from experience so strong that it overrides all but the most basic biological instincts. Unlike the nineteenth-century version, modern "social Darwinism" really is based on Darwinian natural selection, coupled with a strong (but highly controversial) faith in the power of the genes to determine human nature.
By: Steven Rose is
Professor of Biology and Director of the Brain and Behaviour Research
Group
at the Open University.
at the Open University.
Darwin is everywhere these days. We have Darwinian cosmology, Darwinian medicine, Darwinian psychology, Darwinian psychiatry, Darwinian economics, Darwinian computing, 'neural Darwinism,' even Darwinian models for cultural change and the history of science. And we have genes for everything too. Not just things we all know about, like eye colour, or diseases like sickle cell anaemia or Huntingtons. there are, we are told, genes for intelligence, sexual orientation, depression, criminal violence, alcoholism, even 'compulsive shopping.' Whether we vote Labour or Tory, are happily married or go in for mid-life divorce, are all claimed to be somehow 'in our genes.' We are, the story goes, lumbering robots programmed by our genes, which 'created us, body and mind' (the phrases are Richard Dawkins'). Individual genes, 'naked replicators,' have become the basic building blocks of life, and chickens merely the egg's way of making more eggs. I doubt very much whether either Charles Darwin himself, or William Bateson, who invented the term genetics, would recognise their ideas or theories in the way the terms are being bandied about today.
Why this extraordinary upsurge? What we might call fundamentalist Darwinism, in the hands of its popular exponents, has become a sort of all purpose explanation for every aspect of our lives - indeed the philosopher Daniel Dennett called it a 'universal acid' that eats through every area of human thought. Perhaps it is because the deep fatalism which lies behind the belief that our human nature is for good or ill somehow 'fixed,' determined by our genes, suits a society in which we have lost the belief that it is possible to create a more socially just world, and where that other great 19th century explanatory principle, Marxism, has been almost fatally damaged by the experience of the collapse of communism. If we seek certainty in the world, the choices seem to lie between fundamentalist religions like Christianity and Islam, and the seemingly scientific fundamentalism of this version of Darwinism. Indeed there is something of the religious in the way fundamentalist Darwinians cling to their certainties. Invoking the name of Darwin to talk about changes in cosmology, culture, or economic modelling, almost always misunderstands and trivialises what remains one of the most important principles in biology.
How can I as a biologist possibly sound so hostile? It is because I want to rescue both Darwin and the ideas about evolutionary and developmental change, the nature of living processes, from the arms of the fundamentalists who in my view abuse them.
That species have evolved is not a theory: it is a central fact of biology. What is at issue is the mechanism of that evolution. Darwinian natural selection is based on three simple and irrefutable propositions:
Like begets like, with minor variations
Some of these varieties are fitter - better able to survive - than others
All creatures produce more offspring than can survive to breed in their turn
It follows that:
• the fitter varieties are thus
more likely to breed than the less fit, and hence to spread in
successive generations.
• and therefore that species
evolve over time.
However, whilst this is a mechanism of evolution, it is, as Darwin himself recognised, not the only one. It is good at explaining how species get better at doing their species thing, but bad at explaining how new species emerge. For this one needs other factors, like founder effects, and above all sheer contingency - chance. Evolution cannot predict the future, and the future may contain the asteroid which wiped out the dinosaurs, or the catastrophes that overwhelmed the weird and wonderful creatures found fossilised in the Burgess shale, which Steven Jay Gould writes about so well in his book Wonderful Life. Fundamentalist Darwinism sees individual genes as distinct, selfish units, beans in a bag. Yet selection can occur at many levels: gene and genome, population and entire ecosystem, all evolve. And there are constraints given by the laws of physics and chemistry. No assembly of genes can produce a human with wings to fly, not because we aren't capable of angelic behaviour but because you can't build a flesh, muscle and bone structure capable of providing enough lift.
Furthermore, fundamentalist Darwinism operates as if there is a simple linear relationship between 'a gene' and 'a phenotype.' Not so. You can't read off the complex four dimensions of a living organism (three of space and one of time) from the single dimension of DNA. Modern molecular biology knows that genes are not beads on the chromosome chain. they are segments of DNA, separated by intervening nucleotide sequences without known function, 'read' by the RNA and protein synthesizing machinery in complicated ways, with alternative splicing, different reading frames, editing and post-translational modification to produce the dynamic constituents of the living cell. in fact DNA is rather an inert substance. It is not the 'master molecule,' the 'blueprint of life,' the 'code of codes' or whatever other grandiose metaphor has been proposed. It is brought to life only in the context of the cellular orchestra of enzymes, energy flow and the membranes which contain them, the properties studied so painstakingly by generations of biochemists and now swept to one side by theoreticians who prefer to model life on a computer than study the real thing. the DNA egg definitely needs the cellular chicken to function.
Understanding life in four dimensions means that we need to appreciate the rules of development, why it is that no-one mistakes a human for a chimpanzee even though we are said to share over 98% of our genes. Development, by which the single fertilised egg becomes the fully formed adult, requires that we understand process and dynamism rather than just the static properties of models. Every molecule in our bodies is synthesised, broken down and replaced at rates varying from thousands of times a second to a few times a year, and yet you will instantly recognise a friend that you saw many weeks ago, and your brain will store memories of events that occurred decades past. This is why as opposed to the term homeostasis, a physiological principle you will find in almost every biology text book, I prefer homeodynamics, to capture this sense of movement through life's trajectory, which I call a lifeline. the paradox of development is that at every instant an organism is both being and becoming. An example: a new born baby has a suckling reflex, by which it draws milk from its mothers breast. Within months it turns into a child, with teeth, and eats solid food by chewing. Chewing isn't simply grown-up suckling. It involves a quite different set of muscles, and the food needs different enzymes to digest it. Thus the baby has both to be a competent suckler, and to be at the same time on its developmental way to becoming a capable chewer. This process of self-construction, sometimes called autopoiesis, is the antithesis of beanbag theories of genes 'for' this or that - one of those shorthand phrases which is so easily misunderstood.
The great evolutionary biologist theodosius Dobzhansky once said 'Nothing in biology makes sense except in the light of evolution.' I think he was absolutely right, but I want to extent his claim. Nothing, I argue, makes sense in biology except in the context of history - by which I mean evolutionary history, developmental history, personal history, and for our own human species, social and cultural history as well. And in order to understand it at all we must take into account the history and presuppositions of our own science, biology.
Don't get me wrong. Take as an example the claim that there are genes 'for' criminal behaviour. there can be no doubt that there is a relationship between a person's behaviour and what is going on inside their bodies and brains. A person committing a crime will experience particular surges of hormones, particular patterns of neural activity, and these will differ from person to person and type of act to type of act. Part of this difference will be accounted for by any person's unique genotype. But what makes a particular act 'criminal' depends on social conventions, context, the state of the law and many other features. Was private Lee Clegg, shooting a teenage joyrider in Ulster when she crossed an army roadblock, a murderer (as the court found him) or a soldier doing his duty (as those who argued for his pardon insisted) ? Whichever he was, the genetic, hormonal and brain processes involved in his aiming and shooting his rifle were the same. And if we want to know why there are so many vodka-soaked drunks on the streets of Moscow, it is more relevant to enquire into the poverty and desperation of living conditions in that society than to study the molecular genetics of alcoholism.
Good science requires that we ask appropriate questions, which relate to the determining level for any phenomenon we want to understand. Genes are not selfish, and cells don't have memory. These are properties that belong to individuals, not molecules, and the metaphors that pretend otherwise serve only to confuse.
E. Darwin and Darwinism
By: Richard Dawkins
To most people through history it has always seemed obvious that the teeming diversity of life, the uncanny perfection with which living organisms are equipped to survive and multiply, and the bewildering complexity of living machinery, can only have come about through divine creation. Yet repeatedly it has occurred to isolated thinkers that there might be an alternative to supernatural creation. the notion of species changing into other species was in the air, like so many other good ideas, in ancient Greece. It went into eclipse until the 18th century, when it resurfaced in the minds of such advanced thinkers as Pierre de Maupertuis, Erasmus Darwin and the man who styled himself the Chevalier de Lamarck. In the first half of the 19th century the idea became not uncommon in intellectual circles, especially geological ones, but always in a rather vague form and without any clear picture of the mechanism by which change might come about. It was Charles Darwin (Erasmus's grandson) who, spurred into print by Alfred Russel Wallace's independent discovery of his principle of natural selection, finally established the theory of evolution by the publication, in 1859, of the famous book whose title is usually abbreviated to the Origin of Species.
We should distinguish two quite distinct parts of Darwin's contribution. He amassed an overwhelming quantity of evidence for the fact that evolution has occurred, and, together with Wallace (independently) he thought up the only known workable theory of the reason why it leads to adaptive improvement – natural selection.
Some fossil evidence was known to Darwin but he made more use of other evidence, less direct but in many ways more convincing, for the fact that evolution had taken place. the rapid alteration of animals and plants under domestication was persuasive evidence both for the fact that evolutionary change was possible and for the effectiveness of the artificial equivalent of natural selection. Darwin was particularly persuaded by the evidence from the geographical dispersion of animals. the presence of local island races, for example, is easily explicable by the evolution theory: the creation theory could explain them only by unparsimoniously assuming numerous 'foci of creation' dotted around the earth's surface. the hierarchical classification into which animals and plants fall so naturally is strongly suggestive of a family tree: the creation theory had to make contrived and elaborate assumptions about the creator's mind running along themes and variations. Darwin also used as evidence for his theory the fact that some organs seen in adults and embryos appear to be vestigial. According to the evolution theory such organs as the tiny buried hind-limb bones of whales are remnants of the walking legs of their terrestrial ancestors. In general the evidence for the fact that evolution has occurred consists of an enormous number of detailed observations which all make sense if we assume the theory of evolution, but which can be explained by the creation theory only if we assume that the creator elaborately set out to deceive us. Modern molecular evidence has boosted the evidence for evolution beyond Darwin's wildest dreams, and the fact of evolution is now as securely attested as any in science.
Turning from the fact of evolution to the less secure theory of its mechanism, natural selection, the mechanism that Darwin and Wallace suggested, amounts to the nonrandom survival of randomly varying hereditary characteristics. Other British Victorians, such as Patrick Matthew and Edward Blyth, had suggested something like it before, but they apparently saw it as a negative force only. Darwin and Wallace seem to have been the first to realise its full potential as a positive force guiding the evolution of all life in adaptive directions. Most previous evolutionists, such as Darwin's grandfather Erasmus, had inclined towards an alternative theory of the mechanism of evolution, now usually associated with Lamarck's name. This was the theory that improvements acquired during an organism's lifetime, such as the growth of organs during use and their shrinkage during disuse, were inherited. This theory of the inheritance of acquired characteristics has emotional appeal (for example to George Bernard Shaw in his Preface to Back to Methuselah) but the evidence does not support it. Nor is it theoretically plausible. In Darwin's time the matter was more in doubt, and Darwin himself flirted with a personalised version of Lamarckism when his natural selection theory ran into a difficulty.
That difficulty arose from current views of the nature of heredity. In the 19th century it was almost universally assumed that heredity was a blending process. On this blending inheritance theory, not only are offspring intermediate between their two parents in character and appearance, but the hereditary factors that they pass on to their own children are themselves inextricably merged. It can be shown that, if heredity is of this blending type, it is almost impossible for Darwinian natural selection to work because the available variation is halved in every generation. Darwin knew this, and it worried him enough to drive him in the direction of Lamarckism. It may also have contributed to the odd fact that Darwinism suffered a temporary spell of unfashionableness in the early part of the 20th century. the solution to the problem which so worried Darwin lay in Gregor Mendel's theory of particular inheritance, published in 1865 but unfortunately unread by Darwin, or practically anyone else until after Darwin's death.
Mendel's research, rediscovered at the turn of the century, demonstrated, what Darwin himself had at one time dimly glimpsed, that heredity is particulate, not blending. Whether or not offspring are bodily intermediate between their two parents, they inherit, and pass on, discrete hereditary particles – nowadays we call them genes. An individual either definitely inherits a particular gene from a particular parent or it definitely does not. Since the same can be said of its parents, it follows that an individual either inherits a particular gene from a particular grandparent or it does not. Every one of your genes comes from a particular one of your grandparents and, before that, from a particular one of your great grandparents. This argument can be applied repeatedly for an indefinite number of generations. Discrete single genes are shuffled independently through the generations like cards in a pack, rather than being mixed like the ingredients of a pudding.
This makes all the difference to the mathematical plausibility of the theory of natural selection. If heredity is particulate, natural selection really can work. As was first realised by the British mathematician G H Hardy and the German scientist W Weinberg, there is no inherent tendency for genes to disappear from the gene pool. If they do disappear, it will be because of bad luck, or because of natural selection – because something about those genes influences the probability that individuals possessing them will survive and reproduce. the modern version of Darwinism, often called Neodarwinism, is based upon this insight. It was worked out in the 1920s and 1930s by the population geneticists R A Fisher, J B S Haldane and Sewall Wright, and later consolidated into the synthesis of the 1940s known as Neodarwinism. the recent revolution in molecular biology, beginning in the 1950s, has reinforced and confirmed, rather than changed, the synthetic theory of the 1930s and 40s.
the modern genetic theory of natural selection can be summarised as follows. the genes of a population of sexually interbreeding animals or plants constitute a gene pool. the genes compete in the gene pool in something like the same way as the early replicating molecules competed in the primeval soup. In practice genes in the gene pool spend their time either sitting in individual bodies which they helped to build, or travelling from body to body via sperm or egg in the process of sexual reproduction. Sexual reproduction keeps the genes shuffled, and it is in this sense that the long-term habitat of a gene is the gene pool. Any given gene originates in the gene pool as a result of a mutation, a random error in the gene-copying process. Once a new mutation has been formed, it can spread through the gene pool by means of sexual mixing. Mutation is the ultimate origin of genetic variation. Sexual reproduction, and genetic recombination due to crossing over see to it that genetic variation is rapidly distributed and recombined in the gene pool.
Any given gene in a gene pool is likely to exist in the form of several duplicate copies, either all descended from the same original mutant, or descended from independent parallel mutants. therefore each gene can be said to have a frequency in the gene pool. Some genes, such as the albino gene, are rare in the gene pool, others are common. At the genetic level, evolution may be defined as the process by which gene-frequencies change in gene pools.
there are various reasons why gene-frequencies might change: immigration, emigration, random drift, and natural selection. Immigration, emigration, and random drift are not of much interest from the point of view of adaptation, although they may be quite important in practice. It is natural selection which accounts for the perfection of adaptation, for the complex functional organisation of life, and for such progressive qualities as evolution may (controversially) exhibit. Genes in bodies exert an influence on the development of those bodies. Some bodies are better at surviving and reproducing than others. Good bodies, i.e. bodies that are good at surviving and reproducing, will tend to contribute more genes to the gene pools of the future than bodies that are bad at surviving and reproducing: genes that tend to make good bodies will come to predominate in gene pools. Natural selection is the differential survival and differential reproductive success of bodies: it is important because of its consequences for the differential survival of genes in gene pools.
Not all selective deaths lead to evolutionary change. On the contrary, much natural selection is so-called stabilising selection, removing genes from the gene pool that tend to cause deviation from an already optimal form. But when environmental conditions change, either through natural catastrophe or through evolutionary improvement of other creatures (predators, prey, parasites, and so on), selection may lead to evolutionary change.
Evolution under the influence of natural selection leads to adaptive improvement. Evolution, whether under the influence of natural selection or not, leads to divergence and diversity. From a single ultimate ancestor, many hundreds of millions of separate species have, at one time or another, evolved. the process whereby one species splits into two is called speciation. Subsequent divergence leads to ever wider separation of taxonomic units – genera, families, orders, classes, etc. Even creatures as different as, say, snails and monkeys, are derived from ancestors who originally diverged from a single species in a speciation event.
Since the 1940s it has been widely accepted that the first step in the origin of species is normally geographical separation. A species is accidentally divided into two geographically separated populations. Often there may be sub-populations isolated on islands, where the word is generalised to include islands of water in land (lakes), islands of vegetation in deserts (oases) etc. Even trees in a meadow may be effective islands to some of their small inhabitants. Geographical isolation means no gene flow, no sexual contamination of each gene pool by the other. Under these conditions the average gene frequencies in the two gene pools can change, either because of different selection pressures or because of random statistical changes in the two areas, After sufficient genetic divergence while in geographical isolation, the two sub-populations are no longer capable of interbreeding even if later circumstances chance to re-unite them. When they can no longer interbreed, speciation is said to have occurred and a new species (or two) is said to have come into being. It is controversial whether geographical separation is always necessarily implicated in speciation.
Darwin made a distinction between natural selection, which favours organs and devices for survival, and sexual selection which favours competitive success in gaining mates, either by direct combat with members of the same sex, or by being attractive to the opposite sex (these are sometimes called intrasexual selection and intersexual selection, respectively, but the usage is misleading). Darwin was impressed by the fact that qualities of sexual attractiveness were often the reverse of qualities leading to individual survival. the gaudy and cumbersome tails of birds of paradise are a notorious example. they must hamper their possessors in flight, and certainly they are conspicuous to predators, but Darwin realised that this could be 'worth it' if the tails also attractive females. A male who manages to persuade a female to mate with him rather than with a rival is likely to contribute his genes to future gene pools. Genes for sexually attractive tails willy-nilly have an advantage that compensates for their admitted disadvantages.
the philosopher Daniel Dennett has written: "Let me lay my cards on the table. If I were to give an award for the single best idea anyone has ever had, I'd give it to Darwin, ahead of Newton and Einstein and everyone else." Comparative judgments like that are hard to make. But on one criterion Darwin's contribution surely heads the field. the sheer power of the idea, measured as the amount of explanatory work that it does, divided by the extreme simplicity of the idea itself, leaves one astonished that humanity had to wait till the mid nineteenth century before one of us thought of it.