Darwin's Life
Charles Darwin was born in Shrewsbury, England, in 1809. His father was a Whig (liberal) physician and he was the grandson of Erasmus Darwin, also a physician and evolutionist. Darwin was sent to Edinburgh to study medicine in 1825–27, but he was repelled by the sight of blood and bored by rote learning. So, he gravitated toward a radical natural history club called the Plinian Society, whose meetings he attended. There, he studied invertebrate zoology informally with the radical evolutionist, Robert Grant. While studying marine animals with Grant, he was introduced to the idea that all animals have similar organs, suggesting a common descent. It was also in Edinburgh that Darwin learned stratigraphic geology, the then new idea that different layers of rock represent different geological periods, with deeper layers predating higher layers.
In 1827 his father sent him to Cambridge to study for the Anglican ministry, because it was rather common in those days for a young man with an inclination toward natural history like Darwin to seek a rural vicarate and combine (in Darwin’s case) beetle collecting with a secure income. The only thing he did at Cambridge that was memorable was to form a friendship with the botanist (and minister) John Stevens Henslow, whom he accompanied on botanizing walks around Cambridge. After completing a theology degree at Cambridge in 1831, he received an invitation instigated by Henslow to serve as unpaid naturalist on the HMS Beagle on a voyage to survey the coasts of Argentina, Chile, and Peru from 1831 to 1836.
During the voyage, Darwin took notes on the geology, fossils, and living species of all the places they visited. He also collected numerous samples, which he sent back to Cambridge. The trip established his reputation as a naturalist. When he departed on the Beagle, Darwin had never questioned the literal truth of the Bible; an alternative way of looking at the world had never presented itself. Somewhere near the end of his trip he began to record notes of a speculative nature in a notebook, the Red Notebook, a practice that continued for about a decade after he returned to England in 1836. Because he wrote something or other in a notebook practically every day, the development of Darwin’s theory is perhaps the best documented of any great scientific or philosophical idea, and historians have poured over the notebooks trying to reconstruct how his theory developed.
While in South America, Darwin made a number of observations that caused him to wonder whether the received view of the fixity of species was correct. The first was the existence in the same locality of fossil species and of currently living species, closely related but not the same. His favorite example was that of the Megatherium, a gigantic fossil armadillo, and present-day armadillos. The second was the observation that on the vast expanse of the pampas (flat lowland plains), with no intervening topographical barriers, the range of one species could grade off into that of another, different, but closely related species. The example he uses is that of two ostriches, the greater rhea and a smaller one, now called Darwin’s rhea. He was obsessed by the analogy between the two cases, one of which suggested change over time (descent)—the other, change over space (geographical distribution), as evidence of descent. He later wrote in his species notebook, "I look at two ostriches as strong possibility of such change—as we see them in space, so might they in time."
The third observation had to do with species he observed in the Galapagos Islands. According to the theory of perfect adaptation, the flora and fauna of the Galapagos should have resembled those of the Cape Verde Islands, off the coast of Africa, which he had visited on the way down. Under the received theory, places with similar climates and habitats should have similar species. They didn’t. The species of the Cape Verdes resembled those of continental Africa—and those of the Galapagos, South America. He began to think how plants and animals could migrate from one place to another.
When Darwin returned, his family connections and fortune allowed him to become a gentleman scientist. He returned to Cambridge and began working on organizing and interpreting his notes from the voyage. Darwin had brought back huge collections from the voyage of the Beagle, and rather than study them himself, he farmed them out: Richard Owen, an anatomist, was given the fossil mammals; and John Gould, an ornithologist, the birds. By mid-February 1837, Owen had ascertained that virtually all of the fossil mammals were extinct prototypes of smaller forms currently inhabiting the South American continent. Then, in March, Darwin met Gould on the street in London and learned the astounding news that finches that Darwin had collected on the Galapagos were not of the same species, but differed from island to island. Darwin was astounded because such a conclusion put the fixity of species in doubt. We know Darwin had still not guessed at these results when he was in the islands because he had failed to label his specimens by island; Gould had to use birds collected by other members of the crew to make this finding. On March 14, Darwin and Gould read papers on the two ostrich species whose ranges were contiguous, and on the 15th, approximately, he wrote the first evolutionary note in the Red Notebook. At that point he became an evolutionist and in July of that year he opened his species notebook. "Since the past March," he wrote in another notebook, "I’ve been impressed with respect to the nature of South American fossils and the species of the Galapagos archipelago. These facts are the origin of all my concepts."
Gould’s revelation not only convinced Darwin of the reality of evolution, but also converted him to gradualism. He had speculated that the smaller rhea of the pampas had originated by a single saltation (mutation, we would now say). The Galapagos birds—with different, but closely related species on different islands—could not be the result of a single saltation. In his Species Notebook C, Darwin notes that "The changes in species must be slow, owing to physical changes slow." That notion is in part owing to the ideas of Charles Lyell (1797–1875), who published the first edition of his Principles of Geology in 1830. Darwin had a copy with him on the Beagle, and it was instrumental in his developing views on the gradual elevation of the southern part of South America. Darwin and Lyell met and became friends soon after Darwin returned to England, and Lyell welcomed his views as supporting his own doctrine of uniformitarianism: that is, the doctrine that the order of nature of the past (with regard to geological phenomena, in the first place) was uniform with that in the present, and so geologists should attempt to explain the geological history of the Earth by analogy with present-day processes and conditions. Since catastrophic, sudden change had not been observed in historical time, geological changes must have occurred over very long periods of time and could be explained by the kind of processes (like erosion or volcanic activity, for example) as we currently observe them. Darwin’s geological observations on his voyage confirmed Lyell’s ideas, as he saw evidence of ancient seabeds on mountain tops and other phenomena suggesting that geology was no more fixed in time than species were.
Darwin moved to London to be closer to scientific circles and continued to work on his journals and secret notebooks. Although he was now convinced of the gradual transmutation of species, he still had not worked out the mechanism that causes evolution, which he didn’t get until about a year later, on September 28, 1838, when he read Thomas Malthus. In a famous passage in his autobiography, he described the event as follows:
In October 1838, that is, fifteenth months after I had begun my systematic inquiry, I happened to read for amusement Malthus I, and being well prepared to appreciate the struggle for existence which everywhere goes on from long-continued observation of the habits of animals and plants, it at once struck me that under these circumstances favorable variations would tend to be preserved, and unfavorable ones to be destroyed. The result of this would be the formation of a new species. Here, then, I had at last got a theory by which to work . . .
Malthus filled Darwin’s head with all kinds of new ideas for research in order to prove his theory. In a pencil sketch written in 1842 there is cryptic paragraph that in part reads:
But considering the enormous geometrical power of increase in every organism and as every country, in ordinary cases, must be stocked to full extent, reflection will show that this is the case. Malthus on man—in animals no moral restraint—they breed in time of year when provision most abundant, or season most favorable . . . —calculate robins—the pressure is always ready . . . a thousand wedges are being forced into the economy of nature. This requires much reflection; study Malthus and calculate rates of increase . . . In the course of a thousand generations infinitesimally small differences must inevitably tell.
For Darwin, conflict and struggle have a positive outcome: they encourage adaptive traits and lead to the strengthening of species and the creation of new ones.
By 1837 the pressure of working on preparing his journal and other manuscripts for publication took their toll on his health and Darwin was forced to recuperate at the home of his Wedgwood relatives in Shrewsbury during the fall. He recovered somewhat in the spring, but came down with a serious illness in June 1838 and suffered from incapacitating episodes of illness for the rest of his life. During this time he became close with his cousin Emma Wedgwood, whom he married in January 1839. For the next few years Darwin continued to progress his ideas on evolution, but put most of his efforts toward publishing the scientific results of his Beagle voyage. He also spent much of the 1840s studying barnacles, both fossil and living. This study required hours of tedious microscopic work and it was this research (published in three volumes) that established his recognition as a superior naturalist among British scientists.
Darwin worked for many years on his theory. But even though he had worked out the principles of natural selection by 1844, he refrained from publishing. It is common among present-day historians to claim that Darwin "delayed" publishing his theory because he feared the wrath of the Anglican establishment. Darwin, however, was a compulsive researcher, and did not want to publish a book about his theory until he had tied up as many loose ends as possible. He spent more than a decade gathering evidence from fields as diverse as animal husbandry and marine biology to provide irrefutable support for the idea of transmutation of species. Although he and Emma had moved to Down House, an estate in the Sussex countryside, he was in frequent contact with his colleagues through voluminous correspondence. He discussed his ideas with select colleagues, generally receiving encouragement to continue his studies. Neither he nor any of his contemporaries described his actions as constituting a "delay."
Nevertheless, he was forced into publicly announcing his ideas by the simultaneous discovery of the mechanism of evolution, natural selection, by another English naturalist, then in Malaya, Alfred Russel Wallace. The theory of speciation by means of natural selection was presented to the Linnean Society on July 1, 1858, with joint credit given to Wallace and Darwin. Darwin then hurriedly completed his book and published On the Origin of Species in 1859. In spite of the deficiencies in the fossil record and the lack of an adequate explanation for heredity, Darwin’s theory was accepted rather quickly by the majority of English biologists because of the sheer mass of data he offered as evidence, the logic of his argument, and the lack of any other satisfying explanation for speciation.
The first chapter of the Origin of Species was on artificial or methodical selection, the kind of selection practiced by plant and animal breeders to secure the traits that they desired. "Natural" selection was thus a natural process that accomplished the adaptation of an organism to its environment by an analogous process. The main idea of the book is that the constant struggle for individual survival leads to individuals with traits favorable to a given environment to be more likely to survive and reproduce than those individual without those traits. Over time this natural selection leads to the development of new species deriving from common ancestors. Darwin had deliberately omitted human evolution from the Origin of Species, hoping thereby to minimize opposition to this theory. But in 1871, he brought out the Descent of Man, in which he drew humans into the same organic world that he accounted for in the Origin. The second part of Descent was devoted to sexual selection among animals: the rules that evolved that govern courtship and mating. Read more on Darwin’s Ideas.
Darwin closely followed the reception of his theories and the controversy that ensued, though he chose to stay out of the spotlight as much as possible. His natural reticence, his frequent illnesses, and the devastating deaths of three of his ten children kept him confined to Down House. He had, however, numerous followers who avidly defended his ideas in public debates and lectures. The young biologist Thomas Henry Huxley was so fierce in his defense of evolution that he earned the nickname "Darwin’s bulldog." The acceptance of evolution by the young scientific crowd and liberal clergy, and their victory over the old guard, led by Richard Owen and Bishop Samuel Wilberforce, presaged a change in the scientific establishment. The change corresponded to the rise of the professional scientist in contrast to the clergyman/naturalist and amateurs of previous generations.
For the rest of his life Darwin continued working on numerous topics, especially botany, often with the goal of producing explicit evidence for evolution and in order to explain the occurrence of seemingly useless traits. One of his great interests was in the complicated "contrivances" one finds in plant flowers that induce bees to pollinate them. There was a similar "contrivance" among barnacles where he identified a "complemental male," a male reduced only to its sex organ, whose sole role was to fertilize females. Such contrivances were important to Darwin because they illustrated the complexity that develops in organisms as part of the process whereby they adapt to their environments.
Darwin died at the age of 73 at his house in 1882. He was buried along with other great figures of English history at Westminster Abbey.
