Darwin’s revolutionary ideas
February 12 is the 200th anniversary of Charles Darwin's birth.explains the significance of his ideas, and why they still spark controversy today.
CHARLES DARWIN'S ideas revolutionized biology in the 19th century, but they also had a profound and lasting impact far outside narrow scientific circles, challenging religious dogmas and affecting almost every field of human knowledge.
Yet Darwin himself was a reluctant revolutionary--a man who shunned the limelight, hated controversy and became physically ill worrying that his ideas would shock Victorian England.
Darwin was a child of the rising liberal bourgeoisie. His paternal grandfather, Erasmus Darwin, was a prominent doctor and freethinker who wrote a speculative work on biological evolution in the 1790s. His mother was the daughter of Josiah Wedgwood, founder of the famous pottery.
Darwin grew up in Shropshire in England, and later attended Edinburgh University to study medicine, but soon discovered he did not have the stomach for it. He transferred to Cambridge with ideas of becoming a country parson, but instead, the botanist John Stevens Henslow ignited his interest in science.
In 1831, Henslow arranged for Darwin to join a surveying voyage on HMS Beagle as personal companion to the ship's captain, Robert FitzRoy. The voyage lasted nearly five years and was the turning point in Darwin's life.
The Beagle took him to South America, the Galapagos Islands, Tahiti, New Zealand, Australia and southern Africa, before returning to England in 1836. Darwin made detailed geological, botanical and zoological observations and accumulated a large collection of specimens. Back in England, he gained respect for his work as a geologist, including proposing a novel theory for the origin of coral reefs.
Much more radically, however, by the time of his return, Darwin had come to privately reject orthodox accounts of the origin of biological species, which viewed them as having been created in pretty much their present forms.
His observations of the similarities between living and fossil mammals, and between the distinct species of plants and animals on the Galapagos Islands and their counterparts on the South American mainland, persuaded him that biological evolution had taken place, even though he was not yet sure how.
WITHIN A few years, Darwin had elaborated his entire theory of evolution. The crucial idea is that evolution is the result of natural selection--organisms that are better adapted to their environments are more likely to survive and reproduce, thus passing on their advantageous traits to the next generation.
Although Darwin formulated his theory as early as 1837, it was to be more than 20 years before he finally made it public.
The main reason for this delay was his nervousness about the materialist implications of his views and the challenge they posed to the dogmas of orthodox religion, regarded by the upper classes as a bulwark of the status quo during a period of social unrest in early Victorian Britain.
In Darwin's account, evolutionary change was largely the result of the random, ultimately purposeless process of natural selection. This suggests a thoroughly materialist picture of the world that banishes vital forces and preordained purposes from nature, and which implies that mental phenomena emerge when matter is arranged in complex ways.
Such ideas undermine not only traditional religious views of divine creation, but also more sophisticated versions of theism, which claim that God works through evolution.
"Love of the deity effect of organization [of the brain], oh you materialist!" he wrote privately in the late 1830s. "Why is thought being a secretion of brain more wonderful than gravity a property of matter? It is our arrogance, our admiration of ourselves."
Darwin confided to his friends that going public with his ideas about evolution would be like "confessing to a murder." In 1839, Darwin married his cousin, Emma Wedgwood, who, unlike him, was devoutly religious, adding a personal dimension to this conflict.
Darwin and his wife moved to Down House in Kent, and from this period onwards, he was in poor health, probably caused at least in part by his intellectual anxieties. But Darwin's family inheritance allowed him to devote his time to science and to accumulate a mass of evidence supporting his views.
Darwin finally went public with his ideas in 1858, after learning that a young Welsh naturalist, Alfred Russel Wallace, had reached similar conclusions. The following year Darwin published his masterpiece, The Origin of Species, which makes a methodical case for evolution.
Darwin argues that natural selection is a real process, analogous to the way in which plant and animal breeders can dramatically alter the characteristics of a group of organisms over a series of generations by permitting only those with desired traits to reproduce.
In the natural world, a population of organisms can become better and better adapted to its environment over a period of time, and the characteristics of its members at the end of the process may be very different from those of their ancestors.
Darwin went on to argue that natural selection is capable of giving rise not simply to new varieties, but to new species, and that it can in principle account for all the characteristics of existing organisms, even "organs of extreme perfection" like the human eye.
In the Origin, Darwin presents an enormous quantity of evidence that natural selection is not only a possible explanation of the origin of species, but that it is the only reasonable one. The data ranges from the pattern of development revealed in the fossil record, to facts about the geographical distribution of organisms, to anatomical and developmental similarities between otherwise very different living things.
Darwin demonstrates that his view can provide satisfying explanations of such matters, while from the point of view of those who believe in divine creation, they remain conundrums.
For instance, the forelimbs of humans, cats, bats, porpoises and horses perform very different functions and have very different forms, but remarkably share the same underlying bone structure. This only makes sense if all these creatures had a common ancestor in the distant past.
EVEN THOUGH Darwin avoided the issue of human evolution in the Origin (a subject he was later to discuss at length in The Descent of Man), its publication inevitably sparked intense controversy. The eminent geologist Adam Sedgwick condemned Darwin's views for their "unflinching materialism," and figures such as Samuel Wilberforce, the Bishop of Oxford, attacked evolution from a religious perspective.
But it was precisely Darwin's materialism that explains the enthusiasm of his contemporaries Karl Marx and Frederick Engels for his new theory. Less than a month after the Origin was published, Engels remarked in a letter to Marx: "Darwin, whom I am just now reading, is splendid."
Marx himself read the Origin the following year and commented to Engels, "Although it is developed in the crude English style, this is the book which contains the basis in natural history for our own view." Several years later, Marx sent Darwin an inscribed copy of Das Kapital (although the story that he wanted to dedicate the second edition of this work to Darwin is a myth).
Although Darwin didn't engage in the public debate around The Origin, several younger scientists, including Joseph Hooker and Thomas Huxley, came to his defense. Within less than a decade, the bulk of the scientific establishment had been won over to evolution, although it took longer for natural selection to be accepted as the central mechanism.
Darwin's ideas were initially viewed as a challenge to the existing social order, but attempts were soon being made to use them in its support. The political theorist Herbert Spencer formulated the doctrine of Social Darwinism, defending laissez-faire economics on the grounds that it represented the principle of the "survival of the fittest" applied to human society.
Darwin's cousin, Francis Galton, founded the eugenics movement, which viewed social inequalities as having a biological basis and advocated intervention to "improve" the human stock.
But while there have been many attempts to link Darwin's ideas to the claim that social inequalities are biologically determined, and while Darwin undoubtedly shared many of the prejudices of his era, there is evidence of the opposite--that his biological theories were shaped by a commitment to human equality.
Darwin was horrified by slavery, and from an early age was a committed abolitionist who believed that all men are brothers. According to a new book by Adrian Desmond and James Moore, his convictions played an important role in leading him to the idea of the common descent of all organisms.
New attempts to use Darwinian ideas to explain social inequality have emerged in recent decades, including sociobiology and evolutionary psychology, which argue that evolution has shaped human beings to live in hierarchical, competitive societies.
But the history of human evolution reveals that the distinctive characteristic of our species is its flexibility, and that for most of human history, our ancestors lived in societies based on common ownership, cooperation and equality.
While Darwin's ideas have been misused by defenders of the status quo, they continue to come under attack from religiously motivated critics who advocate creationism or its somewhat more sophisticated variant the theory of "intelligent design."
The truth is, however, that Darwin had already refuted such ideas 150 years ago. Today, they are utterly without merit, and represent an attack not just on evolutionary biology but on scientific rationality itself. Although Darwin did not get everything right, the evidence for evolution has only increased since his death in 1882.
Darwin's ideas represent one of the great achievements of humanity's efforts to understand the natural world. Properly understood, they should be part of the arsenal of everyone fighting for progressive social change today.