The Origin of Species

By Charles Darwin

Ussher-ing in Evolution

It is hard to think of a single book that has had greater impact on science and society than The Origin of Species. At the time George Eliot remarked that it "makes an epoch", and today Neo-Darwinism's great champion Richard Dawkins is of the opinion that it did nothing less than unlock the meaning of life; that it started the process that has enabled science to replace the constant human search for 'why?' with the question of 'how?' A bold claim perhaps, but there is no doubt that Darwinism and Neo-Darwinism have done an enormous amount to unravel many of humanity's myths of its place in nature. Equally, it is a mistake to assume that Darwin's theories proposed in The Origin of Species were entirely revolutionary. Like all scientific discoveries, Darwin was drawing on a tradition of thought that question the orthodox view of the nature of the world.

It is useful at this stage to summarise briefly the theory at the heart of The Origin of Species. The full title of the book when published was the snappy On the Origin of Species by means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life. In extreme summary, it maintained that species had not been independently fabricated by a Creator, but had arisen from a single common ancestor (or at least very few common ancestors) and had changed their form through "descent with modification". The chief agent of this change, according to Darwin, was the process of Natural Selection. Natural selection refers to the process by which environmental pressures lead to varying degrees of survival and reproductive success among individuals of a population of organisms with different hereditary characteristics. Those individuals with characters that are better suited to existence and reproduction in a particular environment and with relation to the other organisms in that environment (i.e. that are beneficial in what Darwin referred to as "The Struggle for Existence") are more likely to survive and produce offspring. This is often referred to (though not initially by Darwin) as "the survival of the fittest", a phrase which will be examined later. Given that there is differential survival of differentiated individuals, the slow change of individuals over many generations under sustained environmental pressure will lead to the differentiation - i.e. origin - of different species. A range of geographical, physical and behavioural factors will either increase or decrease the likelihood of speciation.

With the discovery of the laws of heredity, genetics, and developments in evolutionary theory, the term 'natural selection' has taken on a different hue and a more refined definition than that proposed by Darwin. However, much has been discovered since the time of Darwin, and one cannot conduct a scientific appraisal of Origin purely in the light of what has been established since, any more than it is possible to criticise the political writings of the nineteenth century for not taking into account twenty-first century statistics and opinions. Origin must be approached largely as a historical document, and as a scientific development on what was known at the time. Today there are countless books discussing modern evolutionary theory (see Missing Links and Further Reading).

Just as much has been learned about evolution since Origin, so Darwin represented an established (but still controversial) tradition of evolutionary thinking. There was, however, much dogma to overcome. The notion of Creationism - that the universe had been bought into being by Divine force - was, and still is, imbedded at the heart of religious belief the world over. For Western European thought, this 'fact' was enshrined in the bible, and in the mid-seventeenth century, Archbishop James Ussher (1581 - 1656) had calculated, through the Old Testament series of 'begattings' and some spurious mathematics, that the world was created in 4004 BC. The English biblical scholar John Lightfoot was so stimulated by this revelation that he additionally calculated that the exact time was October 26 at 9.00am. Absurd as this all seems now, Ussher's date was widely accepted and included in the page margins of many editions of the King James Bible. Indeed, the term 'prehistoric' did not exist until the mid-nineteenth century, and until the notion that the history of the universe was a short period of time sandwiched between endless tracts of eternity was replaced by the recognition of the enormous age of the earth, evolutionary theories stood no chance of being seriously entertained. Moreover, a central tenet of Christian faith was the infallibility of God, and the world must be an unaltered replica of that which God had created. No species could be lost or altered - both change and extinction were impossibilities. Fossils, therefore, posed an awkward problem, one that was overcome by the notion that God had destroyed forms of life in disasters such as the Biblical Great Flood. As more and more fossils in distinct geological layers and of increasing complexity came to light, this Catastrophism gave rise to the idea of Progressionism. Progresionism held that each level of fossilised remains represented a separate act of creation. In other words, there was no question of descent or transition from one stage to another. Each form represented a rung on the Great Chain of Being - an imaginary ladder that ran from inanimate matter to the peak of the divine being and encompassed the various ranks of living things. Man was conveniently positioned halfway up this flight of stairs, as Alexander Pope put it in his Essay on Man 'Placed on this isthmus of a middle state... In doubt to deem himself a god, or beast... Created half to rise, and half to fall.' Such a Great Chain of Being was also convenient for those who sought to uphold the traditional hierarchical structure of human society. Later the concepts of Darwinism would both help to undermine this traditional structure as well as be misinterpreted in attempts to bolster it.

Far from opposition to evolutionary theories being purely religious or political dogma, the evidence of science seemed to give strong clues to the truth of Creationism - principally the notion of intelligent design. The world was full of organisms so efficiently and perfectly adapted to their environments, with features so perfectly adapted to their functions that this alone was seen as evidence of design. This was most famously encapsulated by Bishop William Paley (1743-1805), with his argument that Nature was the living record of intelligent design and thus the existence of God. His metaphor was that if one had never seen a watch but had stumbled across one, the only way to account for its complexity and efficiency of mechanism was that it had to have been deliberately designed, and this automatically implied the existence of an intelligent designer. Applying this argument to natural complex structures such as the eye, the only conclusion that could be reached was that it had been created by an intelligent designer. Richard Dawkins brilliantly subverts this metaphor in his book The Blind Watchmaker in arguing for the evidence of evolution by natural selection, and the argument that 'you can't have an eighth of an eye' has become a favourite challenge to evolutionists in explaining biological complexity. (See Objecting to the Evidence and Further Reading). However, before the formulating of his own theory, Charles Darwin was fully persuaded by Paley's logic, thinking it the most plausible explanation for the efficiency of nature. Another hurdle that evolutionary thought was forced to negotiate was the Platonic notion of Essentialism. According to Plato, the physical world was a reflection of changeless ideal forms - permanent stereotypes that outlasted change and transcended variation. Essentialism had long been countered by the theory of Nominalism which held that abstractions or 'universals' were without essential or substantive reality, and that only individual objects had real existence. The universals - woodpecker, goat, snake - were held to be merely names, hence Nominalism. The conflict between Essentialism and Nominalism that became prominent in the eleventh and twelfth century was one of theology and philosophy, but Essentialism was later picked up by biologist seeking an explanation for the development of organisms from sperm and egg: a 'finished' organism was perceived as the expression of the 'idea' or 'model' of that organism contained in the sperm (or the egg, or both, depending on who you listened to.) Rarefied and unscientific though this sounds, there remained shadows of the debate between Essentialism and Nominalism in Darwin's discussion in Origin as to what constituted a species. His conclusion that in many cases 'species' becomes an arbitrary distinction and sometimes indistinguishable from 'variety' owed much to the Nominalist camp: an individual organism can be said to belong to one or other named species, but the constant action of natural selection ensures that there is constant potential to transcend the 'ideal type' of that species. (Again the notion of selection at a genetic level paints Darwin's views in a slightly different light.)

Discussion of ideas that were losing favour even before Darwin published Origin may seem a little irrelevant, but throughout Origin he not only seeks to prove his own theory but also shows why matters in nature could not be so if the various theories of special creation were to be true. But it was not nearly enough to say that creatures had evolved. Indeed this was not in itself a revolutionary theory. The most famous of pre-Darwinian evolutionists was the French biologist Jean Baptiste Pierre Antoine de Monet, Chavalier de Lamarck (1744 - 1829). He had outlined a system of evolution some fifty years before Darwin's, based on the idea of the inheritance of acquired characteristics. This 'just-so' approach to evolution in which animal pass on traits they acquire during their life was based on the principle of an inherent drive towards increasing complexity and the shaping power of the environment. A giraffe that spent its life stretching to reach the highest branches would pass to the next generation the longer neck it had spent its life developing. Such a mechanism has been comprehensively disproved, first by the German biologist August Weismann (1834 - 1914), though it remained credible long enough to plague Darwin and his theories. (see The Spectre of Lamarck).

Lamarck was not the only scientist to conceive of a system of evolution, or a connection between mankind and the animals. At the end of the eighteenth century Lord James Burnett Monboddo in Of the Origin and Progress of Language, (1773-92) had insisted (to much mockery) that the orang-utan was a brother to Homo sapiens at an earlier point in his development. 1844 saw the anonymous publication (it was later revealed to be the publisher Robert Chambers) of Vestiges of the Natural History of Creation, which maintained that the fossil record was evidence of the continuous transformation of God's original creation. And in 1852, Herbert Spencer, who was later to take up the Darwinian baton for political purposes (see Natural Selection and 'The Survival of the Fittest'), had proposed a general theory of evolution.

But, any evolutionary theory, however credible, would only be possible given a sufficient time-span for it to operate in, and it was not until the late eighteenth century that geologists began to recognise the true age of the earth. Not only this, but the evidence of geological change was crucial for the notion of concomitant biological change. The doctrine of Uniformitarianism, that held that the Earth had undergone gradual change over millions of years through the processes that were still evident - wind, rain, erosion, subsidence, volcanic activity and so on - was first proposed in 1788 by geologist James Hutton (1726 - 97). Though largely overlooked at the time, these ideas were taken up and popularised by Charles Lyell (1797 - 1875). Though Lyell had trouble accepting the broadening of his theories of geological change to biological evolution, he was to prove a crucial influence on Darwin who had Lyell's Principles of Geology with him during the voyage of the Beagle. Origin contains no less than fifteen references to the work of Lyell, and Huxley later wrote, "I cannot but believe that Lyell was for others, as for me, the chief agent in smoothing the road for Darwin."