Darwin, Charles (1809–1882)

Charles Darwin was the British naturalist who first formulated the theory of biological evolution by natural selection, widely regarded as the most significant scientific achievement of the 19th century. Darwin's paternal grandfather was the 18th-century physician and freethinker Erasmus Darwin, who wrote a speculative work on biological evolution, titled Zoönomia, in the 1790s. His maternal grandfather was Josiah Wedgwood, founder of the famous pottery. Darwin grew up in Shropshire and later attended Edinburgh University to study medicine, but soon discovered he did not have the stomach for it. Transferring to Christ's College, Cambridge, he came under the influence of John Stevens Henslow, professor of botany. 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 5 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.

During his long trip, 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 a novel theory of the origin of coral reefs, but by this time Darwin had also privately rejected 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 being that evolution is the result of natural selection, whereby 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 challenging 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 1839, the independently wealthy 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, Darwin was in poor health, which some have speculated was exacerbated by his intellectual anxieties.

Darwin did not go public until 1858, after learning that the 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 individuals with desired traits to reproduce. In the natural world, a population of organisms can become better and better adapted to its environment over time, and the characteristics of its members at the end of the process may be very different from those of their ancestors. Darwin goes 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.

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