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British naturalist, Charles Darwin is certainly not the inventor of the theory of evolution but his work on'origin of species and his theory of natural selection gave a new dimension to evolutionism. He becomes the avatar of this scientific theory which considers that species evolve over time and gradually generate new species or disappear. The most emblematic case is obviously the common ancestor between Man and apes. Between scientific progress, spiritual questioning and ideological recovery, discover the genesis of the most overwhelming theory of the 19th century.
Charles Darwin inventor of the theory of evolution?
Charles Darwin was born February 12, 1809 in England. After unfinished medical studies, he became a pastor. Darwin frequented scientists such as geologist Adam Sedgwick and naturalist John Stevens Henslow and quickly developed a passion for the study of species. Many authors have supported the idea that species can transform. When Darwin studied this current, already very present, stood up to the fixists who considered that no species had appeared since the divine Creation. The most famous of evolutionists is then the French Lamarck who explains that by an internal will the living beings manage to develop new organs adapted to their needs such as for example the neck of the giraffe which would have stretched out to catch higher leaves.
Darwin is a pure product of the English scholarly bourgeoisie, his two grandfathers having been very involved in the anti-slavery society and his paternal grandfather Erasmus Darwin himself having published in 1794 a substantial work defending the evolutionist theses: Zoonomy or Laws of organic life. In the 1850s, even before Darwin's theory came out, biologist Huxley and paleontologist Owen openly clashed over the connection between man and ape. Their debate is relayed by the press and divides the public. However, if Darwin's work did not initiate the debate, it is clear that it has transformed our relationship with humans to this day. And yet nothing seemed to predestinate this mediocre student Darwin to surpass Lamarck in fame!
A student in the footsteps of Alexander Von Humboldt
Darwin received his own poor education at Shrewsbury School, where he entered at age 9. However, the child is already passionate about all kinds of experiments and even has a small laboratory at home. His often smelly experiences earned him the nickname “Gas”.
In 1825 he entered the Edinburgh medical school, where his older brother was already living. The medical branch becomes a family specialty. This faculty is very famous but in fact the level of the professors has fallen well below the reputation of the establishment, pushing some pupils to take additional courses in private establishments.
The results of his medical studies were mixed, he certainly acquired skills, even seeing a few patients during a family stay. But he is traumatized by the dissections and especially by two operations which he attends. Operations on children, without anesthesia. But Edinburgh is above all an opportunity for Darwin to better train himself in the natural sciences, which he chose as an option from the 2nd year. He also joined a student association, the “Plinian Natural History Society” which debates political and scientific issues. He especially met Robert Grant, a doctor and zoologist specializing in the anatomy of invertebrates who had studied in Paris with Cuvier and Geoffroy Saint-Hilaire. This man is passionate about Lamarck and an amateur of the works of Erasmus Darwin, he pushes Darwin to deepen the theme of the transmutation of species. Darwin will always remain distant from the idea of internal thrust peculiar to Lamarckism, but even if his grandfather's work seems very speculative to him, he will remain forever imbued with transmutation and its justification!
He left Edinburgh in 1827, made a brief trip to Paris and returned home where he spent his time hunting, to the chagrin of his father who sent him to Cambridge to become reverend. A situation which does not necessarily displease Darwin: if he can doubt the creed he is a believer and after all many naturalists were ecclesiastics. During this stay in Cambridge Darwin said he wasted his time, although two points made his stay at this school prolific:
- The excellent courses of botany of the Reverend Henslow with whom he binds a true friendship.
- A geological expedition in North Wales with Adam Sedgwick. This man is an ardent fixist but introduced Darwin to the true scientific process: gathering facts to draw laws or general conclusions.
Darwin is a fervent admirer of Alexander Von Humboldt (1769-1859) a great German explorer and theorist who among other things traveled extensively in South America and left scientific and biographical works. Darwin also wants to go on an expedition to the Canaries. He is helped in this by Henslow, contacts are even made with London merchants to try to find a ship. Then comes the opportunity to Beagle !
Captain Fitz Roy is looking for a naturalist and companion for a 2 year expedition to South America. At 22 Darwin introduces himself, is accepted and manages to convince his father. The expedition has three goals: to improve the maps of South America, survey the coasts of Patagonia, Tierra del Fuego and the Falkland Islands, and finally record weather conditions, tides and winds. All to identify the best trade routes and landing points in the context of the expansion of British maritime trade.
The Beagle is a small boat 27m long, Darwin's cabin is 3m x 3.5m and he shares it with 19-year-old John Lort Stokes Assistant Surveyor. Low ceiling, 3 chairs, 1 table and 2 hammocks. They have lunch in the captain’s cabin and benefit from a 245-volume library equipped with measuring instruments. In total 64 passengers including an artist, a doctor, an instrument maker, servants and 3 natives of Tierra del Fuego brought back by Fitz Roy from a previous trip, presented to the English sovereigns, educated at the captain's expense and that the 'we want to reintroduce them into their tribes to make them vectors of evangelization and civilization. The departure took place on December 27, 1831 for a trip that lasted 4 years and 9 months.
At each stopover Darwin sets out to explore and collects specimens of flora and fauna, fossil and lithic samples ... He observes the habits of animal species, describes them, compares them with similar species from other regions ... He studies the contents of their stomachs, naturalizes them… And keeps the metropolis informed by regularly sending reports and samples to Henslow who is responsible for making known the elements collected. He reads the Principles of geology of Charles Lyell who convinced him that the changes in fauna must have been gradual, over a long time, because of the geological changes of the earth's surface according to laws still in action. Darwin never stops looking for the origins of the mutations and progressive disappearances of species. He agrees with Lyell on the fact that simple changes like the introduction of a new species can be the cause of the disappearance of another species: the sheep in Latin America encroaches on the territory of the guanaco and threatens its survival by example.
The collection of determining elements in the career of the young naturalist
The study of atolls and their formation is a founding element in Darwin's scientific reputation. His explanations are still valid today. He explains the formation of atolls by the sinking of volcanic islands around which a coral reef continues to proliferate. The barrier survives as the volcano disappears, the coral does not proliferate in the center of the atoll where the water is too calm. In this he contradicts Lyell who recognizes Darwin's theory.
On his return, Darwin would make various publications on this subject which established his reputation and opened the doors to the Geological Society of which he became secretary. But it is with the Galapagos Islands that he will find the key elements that will forge his theory. He notes that on these recent volcanic islands (resulting from a hot spot, estimated at 5 Ma) there are animal populations that are very close and yet easily differentiated and above all endemic.
Darwin will describe and bring back several specimens of turtles. But above all, he will study and collect many finches which diverge from those present on the continent, and which differ from each other, by the shape of their beak. A great variety of form induced by a diversity of food following the colonization of many ecological niches in these virgin islands. It is not known whether Darwin immediately understood that he was dealing with the results of the radiation of the same species and its transmutation into several different species.
Perhaps at this point in his journey Darwin saw only variation of the same species to adapt as was already agreed by Lyell. But the fact is that on his return these birds will be studied by John Gould who will affirm that these are different species, which proved to be decisive in the maturing of the Darwinian theory!
Darwinism and natural selection
The Beagle landed on the English coast on October 2, 1836. On his return Darwin entrusted almost all of his samples to the people most qualified to study them: Henslow for the plants, Owen for the fossils, John Gould for the birds… They are the object multiple publications that Darwin had gathered in a book, Zoology of the Beagle Voyage whose volumes appeared from 1838 to 1843. It was also in 1838 that he became secretary of the Geological Society for his work on the atolls. In addition to his theory on transmutation Darwin will take care to make a few other scientific publications so that his skills cannot be questioned when he publishes his main thesis. He thus worked on earthenware but also and above all on cirripeds, with a new species that he had brought back from Latin America. His work on corals and cirripeds earned him the Royal Medal!
On his return he also wrote his travel journal which was published in 1839 and was part of his celebrity. He also wrote his famous notebooks where he gradually worked out his theory. A geology notebook, 4 on the transmutation of species and 2 on Man and the spirit.
Darwin is obsessed with the mutation of species, for his study he breeds plants and pigeons of all kinds and takes a keen interest in their behavior and variations. He learns a lot about artificial selection, how humans choose between variations of the same species. He sends out printed questionnaires to breeders and gardeners. Finally, reading Malthus makes him realize that any species could grow indefinitely if it were not for the barrier of food availability that induces a struggle between individuals. Malthus used Nature to justify a social system rejecting the welfare state which only fuels pauperization. Taking up the concept, Darwin retransposes this social doctrine in the natural sciences. The struggle between individuals must regulate the population. He deduced his theory on the principles of natural selection:
- All species naturally have random variations.
- If this variation is bothersome for the animal, there is a good chance of dying early or not finding a sexual partner. Thus his descendants are minimal or zero and the variation disappears with him.
- If a variation allows animals to survive an ecological crisis or have more sexual partners then their offspring will be more numerous and the variation is diffused.
- From variation to variation, a population may move further and further away from the parent species to the point of forming a new species.
But Darwin does not yet have all the elements to make his theory infallible. He does not know, for example, the origin of the variations and does not have a typical line, fossil or living, proving the progressive differentiation from one species to another.
However, he tests his theory by debating it with learned friends whom he meets at his home in Downe, Kent, two hours outside London. Among this knowledge is Alfred Rund Wallace, naturalist and rare species hunter on behalf of collectors. The latter also wonders about the evolution of species and is preparing an article which he sends to Darwin in 1858. Wallace's theory, which is indeed his work, is very similar to Darwin's! To avoid being cut off from under his feet in the field of scientific publication, Darwin was forced to prematurely publish an extract from his work on July 1, 1858. But the elements presented passed into general indifference and we had to wait for the full publication on November 24, 1859 for the debate to rise!
If Darwin has made the choice not to deal with Man, it is all the same around him that the whole debate is tied since Darwin's theory considers all living things coming from a common ancestor, gradually differentiated. into various species by natural selection. Darwin will not feel capable of holding an oratorical contest and will generally be satisfied with responding to attacks in reissues of his work. But others will take it upon themselves to defend it in public, in learned societies but also in academia as in the person of Huxley, old enemy of the old paleontologist Owen! He will be "Darwin's Bulldog"! If the theory provokes an outcry among creationists, it is notable that evolution was already a notion that was beginning to take root in scientific circles and that it was the mechanism that was no longer subject to debate.
So when the theory arrives in France, Darwin's theory leads above all to a strengthening of Lamarckism! Aware of the interest aroused by the place of Man in the animal kingdom, Darwin devotes a book to him published in 1871: Male descent and selection linked to sex. Its goal is then to desecrate Man considered by many, even among evolutionists, as apart because endowed with a consciousness of divine essence. Darwin's work will be to study the physical expressions of feelings, to find that they are the same between the different human races (he sends numerous questionnaires to missionaries and governors throughout the Empire) and to compare them with his work on the expression of emotions in animals. He deduces that in animals as in humans there is the same range of emotions, often physically expressed in close proximity. Its aim is to show that many behaviors, even social ones, are inherited, resulting from the instinct acquired at a very early stage of our evolution. More than the origin of species, this work is the real motif of the many caricatures of Darwin as a man ape which circulated at the end of the 19th and the beginning of the 20th century.
Darwin and the theory of the origin of species
Darwin's theory implies in fact that only the lineage survives those who are most able to survive in times of crisis (natural selection) and / or the most able to reproduce (sexual selection). Inspired by the sociology of Malthus, this theory returns to sociology through authors like Galton (cousin of Darwin) who in 1908 founded a "society of eugenic education" with Leonard Darwin (eldest son of Darwin). Eugenics is the desire to allow higher beings the possibility to supplant, socially and even sexually, the weaker ones. And thus not to stop the complexification of living things at work from the beginning. Darwin himself seems to subscribe in part to this movement.
Although Darwin sometimes tended to temper these remarks by specifying that social cohesion is one of the forces developed by the species to survive, only these lines remain in Male descent and sexual selection are one of the bases of social Darwinism.
Eugenics can take various forms according to two trends still present today: "positive" eugenics which consists in valuing superior beings (sperm bank, equal opportunities at school, etc.) and "negative" eugenics. Which consists in neutralizing the defects of the species (authorization in France of abortion for medical reasons; during totalitarian regimes: sterilization of patients, regulation of sexual relations between races, elimination of races considered the most inferior, etc.)
Alas as Nietzche wrote in Twilight :
The struggle for existence " unfortunately ends in a way that is contrary to what Darwin's school wanted, to what one would perhaps dare to desire with it: I mean at the expense of the strong, the privileged, the happy exceptions. Species do not grow in perfection: the weak always end up mastering the strong - this is because they have the great number, they are also more cunning ».
The eternal question is who are the strong ones to select?
Denis Buican, author on the subject, concludes on the great massacres of Hitler and Stalin:
« It was the selection of the worst ... and the worst torturers ... and, moreover, often to the applause of the weak in spirit, even more numerous than the sadists. »
In conclusion, it emerges that the work of Darwin (died April 19, 1882), while it does not inaugurate the theory of evolution, gives it credibility by providing a rational explanation of its mechanisms. A judicious theory largely confirmed and completed today thanks to advances in genetics. But a theory which leads to the desacralization of man. Theory born out of sociological studies which returns to the sphere of sociology with a desire to improve humanity but which unfortunately often only materializes for the benefit of the capitalist spheres profiting from the struggle for work, or for the benefit of totalitarian regimes based on a struggle between races or between classes.
• Gayon Jean, Darwin and after Darwin: a history of the natural selection hypothesis, Paris, Editions Kimé, 1992.
• Lecointre Guillaume (ndd), Critical Guide to Evolution, Paris, Belin, 2009.
• Darwin Charles (edition and choice of texts by Jérôme Picon), the origin of species, Paris, Flammarion, 2009.