|
CHARLES DARWIN BIOGRAPHY |
by John van Wyhe, Ph.D.
Few Victorians are as well-remembered today as Charles Robert Darwin. Born into a wealthy Shropshire gentry family, Darwin grew up amidst wealth, comfort and country sports. An unimpressive student, Darwin vacillated between the prospect of becoming a country physician, like his father, or a clergyman. The advantage to becoming a country parson, as Darwin saw it, would be the freedom to pursue his growing interest in natural history. However, an unforeseen opportunity precluded Darwin's plan of becoming a clergyman. After his student days in Edinburgh and Christ's College Cambridge, Darwin's connections in 1831 offered him the opportunity of travelling on a survey ship, H.M.S. Beagle, as naturalist and the captain's gentleman dining companion. The round-the-world journey lasted almost five years. Darwin spent most of these years investigating the geology and life of the lands he visited, especially South America, the Galapagos islands, and pacific coral reefs. Darwin also read the works of men of science like Alexander von Humboldt and the geologist Charles Lyell. Lyell's new book, Principles of Geology, was particularly influential for Darwin. Lyell argued that the world had been shaped not by great catastrophes like floods but by the gradual processes we see active around us: wind, erosion, volcanoes, earthquakes etc. Lyell offered not just a new geology but a new philosophy of science. Slow gradual cumulative change over a long period of time could produce great effects. Visible non-miraculous causes should be preferred when seeking explanations. Darwin had the opportunity to witness all of these forces himself during the Beagle voyage and he became convinced that something like Lyell's method was correct. Darwin also collected organisms of all sorts, as well as unearthing many fossils. He began to speculate on why it was that the species he found as fossils were often extinct in the same region today, but sometimes not. The evidence clearly showed that the environment had sometimes changed. Where had new species come from? Darwin did not hit on a solution during the Beagle voyage, but rather a few years later in London, while writing books on his travels and studying the specimens he had collected. He began to speculate on how species could arise by means still active around us. Darwin's idiosyncratic eclecticism led him to investigate some unconventional bodies of evidence. He made countless inquiries of animal breeders, both farmers and hobbyists like pigeon fanciers, trying to understand how they made distinct breeds of animals. Gradually Darwin decided that organisms were infinitely variable, and that the supposed limits or barriers to species were a myth. In modern terms we would say that Darwin came to accept the then very controversial and unorthodox view that life evolves. Darwin then sought to understand how evolution worked. Darwin was familiar with the evolutionary theories earlier proposed by his grandfather Erasmus Darwin and by the great French zoologist J.B. Lamarck. In 1838 Darwin read the Rev. Thomas Malthus's Essay on the Principle of Population (1798). Malthus had argued for a law-like relationship between population growth and food production in order to warn against what he feared was an immanent danger of human overpopulation. Malthus was widely believed to have conclusively demonstrated that population growth would necessarily outstrip food production unless population growth were somehow checked. The focus of this scheme inspired Darwin who applied it to his much wider field of concern. Surely all species could breed enough to fill the earth—yet did not. Clearly many offspring did not survive. Darwin, already concentrating on how new varieties of life might be formed, now thought in terms of the differences between those individuals who, for whatever reasons, left offspring and those who did not. As Darwin wrote in his autobiography in 1876: 'In October 1838, that is, fifteen months after I had begun my systematic inquiry, I happened to read for amusement Malthus on Population, 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 favourable variations would tend to be preserved, and unfavourable ones to be destroyed. The results of this would be the formation of a new species. Here, then I had at last got a theory by which to work'. Below is the famous passage from Darwin's personal notebook where these ideas were first recorded:
Therefore if checks killed off some individuals but not others, the survivors would pass on their own form and abilities. They would increase whilst other forms would decrease. Darwin did not know how inheritance worked—genes and DNA were totally unknown. More importantly he realized the crucial point that inheritance occurred. Darwin thought in terms of populations of diverse heritable things with no essence—not representatives of ideal types as many earlier thinkers had done. From his observations of domesticated plants and animals it seemed that there were no limits to the extent organic forms could vary and change through generations. Thus the existing species in the world were related not along a chain of being or in statically separate species categories but were all related on a genealogical family tree through 'descent with modification'. Darwin called his mechanism natural selection as it was similar to the way breeders modified populations by selecting desirable forms in domesticated plants and animals. Darwin also identified another means by which some individuals would have descendants and others would not. He later called this sexual selection. This theory explained why male birds often have bright plumage which might make them easier to spot by predators or why the males of some species, such as pea fowl, have enormously enlarged tail feathers used for mating displays but apparently costly in every other respect. The realization that collections of mockingbirds and finches that he and others had collected on the Galapagos Islands were specific to particular islands spurred Darwin to wonder why slightly different species inhabited each island. Darwin thought it too unlikely that each species had been generated or individually created on each island. With his ideas of inheritance and divergence from an ancestral stock Darwin could show that isolation provided by the Galapagos Islands allowed animal populations to diverge from the ancestral stock while adapting themselves to the local conditions on each island. Thus speciation, or the splitting into new species, could occur simply by ongoing variation, selection and inheritance in isolation from the ancestral population. Darwin, deeply studied in the sciences of his time, yet living somewhat removed from his colleagues as a closet theorist, was able to think in new ways and to conceive of worlds quite unimaginable to his orthodox friends. However, the legend of Darwin as a lone genius discovering evolution by natural selection on the Galapagos Islands is a legend whose fabrication we can reconstruct. Nevertheless, it seems to be so widespread today that nothing scholars say to the contrary can dislodge it. Perhaps the best antidotes are the excellent biographies of Darwin by Janet Browne (1995, 2002) and Desmond and Moore (1991). Many have argued that Darwin borrowed an idea of individual struggle from laissez-faire social theory and applied it to the natural world. Karl Marx was perhaps the first to observe that Darwin's theories of individual struggle resembled contemporary British theories of political economy. The logic of these social theories is powerful. Nevertheless, the specific causal connections between these social factors and Darwin's thought remain unclear. Although Darwin's theories were not isolated from the social environments in which he lived, we should remain open-minded when explaining Darwin's thought. Darwin spent most of his time thinking about the properties of organisms, how they all varied to some degree, how apparent lineages resembled one another, and how the rigours of nature meant that a vast quantity of life was constantly being snuffed out in a natural winnowing of forms. The important point for Darwin was not the survival of an individual, or as Herbert Spencer called it, the 'survival of the fittest', but success in creating offspring—in the perpetuation of a stock. After all, Darwin named his theory 'natural selection' not 'individual competition' or 'survival of the ruthless'. Darwin did not, at first, tell anyone about his secret speculations. Perhaps the first colleague to be told was his correspondent, the botanist J.D. Hooker on 14 January 1844: 'I am almost convinced, (quite contrary to opinion I started with) that species are not (it is like confessing a murder) immutable'. The unorthodoxy and anathema attached to the idea that species might not be fixed was a powerful force. Darwin told only a handful of other friends of his ideas during the succeeding years. Meanwhile Darwin married his cousin Emma Wedgwood in 1839 and continued to study and publish on a variety of scientific subjects achieving a great reputation as a naturalist and traveller. His eight years grueling work on barnacles, published 1851-4 established Darwin's reputation as an authority on taxonomy as well as geology and the distribution of flora and fauna as in his earlier works. Darwin conducted breeding experiments with animals and plants and corresponded and read widely for many years to refine and substantiate his views on evolution. In 842 he prepared an essay outlining his evolutionary theory but did not publish it. He waited until 1858 when a letter from an English naturalist and collector, Alfred Russel Wallace, in the Malay Archipelago moved him to action. In this fateful letter Wallace described his ideas 'On the Tendency of Varieties to Depart Indefinitely From the Original Type'. The similarity to Darwin's own notion of natural selection was striking. Darwin sent the letter on to Lyell and it was decided, to avoid competition for priority, to publicize abstracts by both men as soon as possible. The papers were read in the absence of Darwin and Wallace at a meeting of the Linnean Society of London in 1858. Darwin worked on creating an 'abstract' of his in work in progress on natural selection. This abstract became one of the most famous books of modern times On the Origin of Species (1859). It is the fact that Darwin possessed an impeccable scientific reputation that led to his fame as an evolutionist. Why is it that we consider Darwin as the originator or discoverer of evolution when so many others proposed similar ideas before him? Why do many still believe that a Darwinian revolution broke across the world like a thunderclap in 1859 when Darwin published The Origin of Species? A glance at Darwin's 'An historical sketch of the progress of opinion on the origin of species' shows that Darwin made no pretence to have originated or discovered evolution by descent with modification. We know that a wide popular literature such as George Combe's Constitution of Man (1828) and the anonymous Vestiges of the Natural History of Creation (1844) had already shocked and converted vast popular audiences to belief in the power of natural laws to control the development of nature and society. Historians of science now believe that Darwin's effect was, as James Secord put it, a 'palace coup' amongst elite men of science rather than a revolution. Darwin, as an unquestionably respectable authority in elite science, publicly threw his weight on the side of evolution, and soon young allies like Hooker, T.H. Huxley, and John Tyndall publicly threw their own weight towards the same position. Darwin's name is so linked with evolution because he was the high-status insider who made evolution acceptable, even respectable. Most of his contemporaries did not particularly like Darwin's primary mechanism of natural selection. Very often in subsequent years evolution was accepted but natural selection was not. In fact, a generation of biologists regarded Darwin as correct in uncovering the evolution of life but mistaken in stressing natural selection. Natural selection's canonization had to wait until the modern synthesis of Darwinism with Mendelian genetics in the 1930s. Like Combe, Babbage, Chambers, Spencer and countless other authors before him, Darwin represented his doctrine as furthering the domain of natural laws. We see this in the following epigraph chosen by Darwin for The Origin of Species:
W. WHEWELL: Bridgewater Treatise. Darwin even saw the power of his law of natural selection extending beyond life to what we would call psychology, linguistics, and to society and history (see for example Descent of Man chapter 3, 1871). In The Origin of Species Darwin first tried to convince his readers that organisms are utterly malleable and not fixed natural kinds. He showed that domestic plants and animals were well known to be highly malleable and to have changed as much under domestication as to be classified as different species by taxonomists. He then showed that the existence and abundance of organisms was dependent on many factors, many of which tended to hold their numbers in check such as climate, food, predation, available space etc. Only then did Darwin set about showing the effects of differential death and survival on reproduction and the persistence and diversification of forms—natural selection. In other words Darwin's theory of evolution has three main elements or requirements: variation, selection and descent or heredity. If all individual life forms are unique, as Darwin convincingly showed, and these differences could make a difference to which organisms lived to reproduce and which did not, then, if these differences could be inherited by offspring, subsequent generations would be descended more or solely from those which were lucky enough to survive. An illustrative example is seen in the recent work of biologists in the Galapagos Islands. During a drought season when no new seeds were produced for an island's finches to eat, the finches were forced to hunt for remaining seeds on the ground. Soon all the visible seeds had been devoured. It so happened that those with slightly thicker bills than average could turn over stones a little bit better than the rest to find the remaining seeds and so they managed to survive the famine. The others perished. When the drought ended and the birds again had young, this new generation was had the slightly thicker bill. This is an example of Darwinian evolution observed and measured in the field. (See Jonathan Weiner, The Beak of the Finch. 1994) Darwin's theory of genealogical evolution (as opposed to earlier theories by Lamarck or Chambers which entailed independent lineages unfolding sequentially because of an innate tendency towards progress) made sense of a host of diverse bodies of evidence such as the succession of fossil forms in the geological record, geographical distribution of life (biogeography), recapitulative appearances in embryology, homologies, vestigial organs, the taxonomic relationships observed throughout the world and so forth. The famous last paragraph of the Origin of Species is a concise and eloquent précis of Darwin's vision:
Modern commentators often misunderstand the meaning of the title of Darwin's book. They take the origin of species to mean the origin of life. Then it is pointed out that Darwin 'failed' to throw light on the origin of life. But this was not Darwin's project. Darwin argued that species—that is the different kinds of organisms we observe—come not from multiple unique creation events on each island or particular place—but instead that species are the modified descendants of earlier forms. Darwin demonstrated that the origination of species could be entirely explained in descent with modification and not spontaneous creations according to environmental circumstances or divine interventions. The reactions to Darwin's evolutionary theories were varied and pronounced. In zoology, taxonomy, botany, palaeontology, philosophy, anthropology, psychology, literature and religion Darwin's work engendered profound reactions—many of which are still ongoing. Most disturbing of all, however, were the implications for the cherished uniqueness of Man. Although Darwin cautiously refrained from mentioning Man in the Origin except for his famous cryptic sentence: 'Much light will be thrown on the origin of man and his history' most people who read the book could think only about what this genealogical view of life meant for Man. This is a subject Darwin later took up in The Descent of Man (1871) and The Expression of the Emotions in Man and Animals (1872). In these brilliantly original and seminal works Darwin showed that there is no difference of kind between Man and other animals, but only of degree. Rather than an unbridgeable gulf, Darwin showed there is a gradation of change not only between Man and other animals, but between all organic forms which is a consequence of the gradual change continuously and cumulatively operating over time. Darwin's massive achievements are not restricted to his early scientific works and his evolutionary works. His keen observation, imagination, curiosity and energy allowed him to make strikingly prescient contributions to ecology, botany and a dozen of what would later be distinct disciplines. Darwin was very impressed by the inter-relatedness of different species, climate and environment. He stressed that the life in any area was the outcome of an amazing history of struggle or war or 'great battle for life'. He proposed new solutions to how organisms spread across the globe. His numerous discoveries and theories are too numerous to list here. In his final book published the year before his death, The formation of vegetable mould through the action of worms (1881) Darwin again made an important contribution which, as was characteristic of Darwin, revealed the amazing complexity and importance of a natural process of gradual accumulation, which no one seemed to have grasped before, and that had all along been under our feet. Charles Darwin was a mild, kind, pleasant man, unassuming and sincerely modest. He suffered from an unexplained illness much of his adult life (perhaps picked up during the Beagle voyage). He nevertheless remained driven and ambitious to explore nature and examine it candidly and to remain part of the elite scientific world he respected and admired. Darwin died in 1882 and was buried in Westminster Abbey. A myth about Darwin still circulates today—that he repented of evolutionism or converted to Christianity on his deathbed. These stories are usually circulated by those who would like them to be true, but they are not. There are no mysteries surrounding Darwin's death; his relatives present at the time wrote detailed accounts of his last hours. The history of the legend, however, is very interestingly and fulsomely revealed in James Moore, The Darwin legend (1994). Darwin was not an atheist, but a deist; that is he believed that some creating intelligence had designed the universe and set up natural laws according to which all of nature was unwaveringly governed.
|
