Charles Darwin is centrally important in the development of scientific and humanist ideas because he first made people aware of their place in the evolutionary process when the most powerful and intelligent form of life discovered how humanity had evolved. The theory of evolution by natural selection was first put forward by Darwin in On the Origin of Species, published in 1859, and his theory is still generally accepted as the best available explanation of the way life on this planet developed.
Darwin’s father was a country doctor in and around Shrewsbury, and the young Charles grew up in an extended family who knew the countryside and its pursuits well. His grandfather was Erasmus Darwin, an eminent naturalist and poet. As a boy he collected beetles, moths and other objects of curiosity, and he and his brother did simple chemistry experiments in the attic of their large house. He attended Shrewsbury School where he did not do particularly well – he was more interested in beetles than in Latin grammar. Neither was he a very successful university student. He was persuaded by his father to study medicine, but did not complete his medical studies at Edinburgh, because he found it “intolerably dull” and could not stand the sight of blood. So he went to Cambridge University to study theology, but here too there were more interesting pursuits than his studies. At Cambridge he met a prime mover in the developing science of Geology, Adam Sedgwick, whom he accompanied on field trips to North Wales and other places. He also met and learned a great deal from Professor Henslow, a wonderful teacher and friend, with whom he chased moths and butterflies across the fens with a big net, and learned to classify plants.
In 1830, when Darwin was only 22, Henslow learned of the imminent departure of a Royal Navy survey ship, HMS Beagle, which was in need of a naturalist. Would Charles like to go? Charles jumped at the opportunity. His father reluctantly gave permission, and the ship sailed from Plymouth on 27 December 1831. The main object was to make good naval charts of parts of South America, which was the speciality of Captain Fitzroy, who was also rather fundamentalist in his religious views. It was while they were surveying the Galapagos Islands that Darwin made many observations which eventually led to his theory of evolution by natural selection, although he barely grasped the significance at the time. “The natural history of these islands is eminently curious,” he wrote in his journal. And so it was: the ten rocky islands were home to many plants and animals that were like those of neighbouring South America , but with distinct differences. Half the species of birds living on these islands occurred nowhere else on the planet. Each island had its own species. How had this come about? Could this extraordinary variety really be explained by the idea that God had created all the species on Earth in six days? Could the variations he saw on the Galapagos have anything to do with the huge scale of geological time he had learnt about from geologists such as Sedgwick? In a tentative way, Darwin argued about these issues with Captain Fitzroy, whose dogmatic religious belief acted as a useful stimulant, though neither knew it at the time. Darwin thought that the unique species of the Galapagos could not have been specially created for each island, but must have evolved from similar ancestors carried from the mainland and washed up on the islands. But how had this evolution occurred?
Darwin worked on this question over the years after his return, during which he married and settled down. He observed that offspring from any species resembled their parents but also varied from them. Any variation that was an advantage for survival would enable those offspring that had it to live longer and to breed more successfully, passing on that advantage to some of their offspring. Even very tiny advantages – a slightly different colouring, for instance, or a better turn of speed, or greater lung capacity – could be passed on, and over long periods of time, successful adaptations would dominate. This process is known as natural selection, summed up by Darwin as: ”Multiply, vary, let the strongest survive and the weakest die”. It explains how species change and why some flourish and others die out. It includes human beings, of course, as part of the natural world, closely related to the smaller apes.
This was (as Darwin well understood) a theory bound to offend established opinion in early Victorian England. (It was also unpopular with his wife.) It meant that there was no need for a creator-god and it placed mankind firmly within the animal kingdom. It was a controversial theory, and Darwin had no taste for public controversy, much preferring quiet research. Though he was probably an agnostic, he was always polite to and about religious believers, and did not want to antagonise them. He wrote uncontroversial studies of barnacles which are still standard texts today. Although his theories on evolution were well known to a small circle of scientific friends in London, he preferred not to publish them. But, one day in 1858, he received a letter from Alfred Russell Wallace, a biologist he hardly knew, who had worked out a similar explanation for the origin of species and wanted Darwin ’s opinion. Darwin ‘s friends insisted that he should publish his ideas and claim joint credit for them with Wallace. A brief joint paper was published, followed by Darwin ‘s revolutionary classic of scientific thought, On the Origin of Species, in 1859.
Darwin observed social feelings in animals and thought that they could be natural and instinctive in humans, not something imposed from outside. “Ultimately a highly complex sentiment, having its first origin in the social instincts, largely guided by the approbation of our fellow men, ruled by reason, self-interest, and in later times by deep religious feelings, confirmed by instruction and habit, all combined, constitute our moral sense or conscience,” he wrote in The Descent of Man (1871), putting forward the idea that morality existed before religion.
Darwin speculated that our moral sympathies could evolve, as human society evolved:
“As man advances in civilisation, and small tribes are united into larger communities, the simplest reason would tell each individual that he ought to extend his social instincts and sympathies to all the members of the same nation, though personally unknown to him. This point being once reached, there is only an artificial barrier to prevent his sympathies extending to the men of all nations and races.” Humanists today tend to think that moral values must have evolved because they are useful to our species.
Darwin was an independent thinker, a great scientist and the most influential biologist in history. The Darwinian theory of evolution caused massive controversy, and is still condemned by some religious people as it contradicts the biblical creation story and undermines claims about the literal truth of the Bible. His friend T H Huxley defended the theory in a famous debate with Archbishop Wilberforce. In many subsequent books and papers Darwin, and biologists after him, developed his ideas and uncovered more evidence from the fossil record, establishing evolution by natural selection as a central explanatory force, a linchpin of modern science.