Charles Darwin Page 13

In the sixth chapter I enumerated the chief objections which might be justly urged against the views maintained in this volume. One, namely the distinctness of specific forms, and their not being blended together by innumerable transitional links, is a very obvious difficulty. [But] the number of intermediate varieties, which have formerly existed, [must] be truly enormous. Why then is not every geological formation and every stratum full of such intermediate links? The explanation lies, as I believe, in the extreme imperfection of the geological record.16

  Now let us turn to our richest geological museums, and what a paltry display we behold! That our collections are imperfect is admitted by every one. … many fossil species are known and named from single and often broken specimens. Only a small portion of the surface of the earth has been geologically explored, and no part with sufficient care … .17

  It would not, therefore, have surprised Darwin to learn that more than a century and a half later ‘intermediate (or ‘missing’) links’ are still being discovered, virtually on a daily basis.

  Chapter 11: On the Geological Succession of Organic Beings

  On Extinction

  The extinction of species has been involved in the most gratuitous mystery. No one can have marvelled more than I have done at the extinction of species.18

  It is most difficult always to remember that the increase of every creature is constantly being checked by unperceived hostile agencies, and that these same unperceived agencies are amply sufficient to cause rarity, and finally extinction. So little is this subject understood, that I have heard surprise repeatedly expressed at such great monsters as the Mastodon and the ancient Dinosaurs having become extinct; as if mere bodily strength gave victory in the battle of life. Mere size, on the contrary, would in some cases determine, as has been remarked by Owen, quicker extermination from the greater amount of requisite food.19

  Thus, as it seems to me, the manner in which single species and whole groups become extinct accords well with the theory of natural selection. We need not marvel at extinction; if we must marvel, let it be at our own presumption in imagining for a moment that we understand the many complex contingencies on which the existence of each species depends.20

  The question of why dinosaurs, the most spectacular creatures ever to have walked the Earth, became extinct will be discussed shortly.

  Chapter 12: Geographical Distribution

  The question arose, wrote Darwin, as to

  whether species had been created at one or more points of the earth’s surface. Undoubtedly there are many cases of extreme difficulty in understanding how the same species could possibly have migrated from one point to the several distant and isolated points, where [that species is] now found.21

  However, he pointed out that there were many factors which influenced the means by which living creatures could be dispersed.

  Means of Dispersal

  Changes of climate must have had a powerful influence on migration. Changes of level in the land must have been highly influential. Where the sea now extends, land may at a former period have connected islands or possibly even continents together, and thus have allowed terrestrial productions to pass from one to the other.22

  Darwin’s own experiments indicated that seeds of certain plants might float on water for in excess of twenty-eight days, and yet still retain their power of germination. Seeds could also be spread by driftwood, via the carcasses of dead birds which floated on the sea with seeds contained in their crops; by living birds which may pass seeds through their intestines; or by seeds contained in soil which adheres to their claws and beaks.23 In the Arctic and Antarctic regions seeds could be carried by icebergs which ‘are sometimes loaded with earth and … brushwood …’.24 Alternatively, ‘Locusts are sometimes blown to great distances from the land; I myself caught one 370 miles from the coast of Africa.’25

  Chapter 14: Mutual Affinities of Organic Beings …

  In this chapter I have attempted to show, that the arrangement of organic beings throughout all time in groups under groups – all naturally follow if we admit the common parentage of allied forms, together with their modification through variation and natural selection.26

  Chapter 15: Recapitulation and Conclusion

  I have now recapitulated the facts and considerations which have thoroughly convinced me that species have been modified, during a long course of descent. This has been effected chiefly through the natural selection of numerous successive, slight, favourable variations …

  This, then, was the essence of Darwin’s great theory, which was based on the results of two decades of meticulous and painstaking research, fieldcraft, and experimentation. So far, so good. But Darwin went on to say that, in his opinion, the ‘modification’ (meaning, in this context, the transformation of an organism from its original anatomical form) of species, had also been

  aided in an important manner by the inherited effects of the use and disuse of parts; and in an unimportant manner, that is in relation to adaptive structures, whether past or present, by the direct action of external conditions and by variations which seem to us in our ignorance to arise spontaneously.27

  Is it possible that ‘modifications’ – i.e. variations – in an organism could be brought about in such ways, and also that such variations could be passed down from one generation to another? This will shortly be discussed in more detail.

  In an attempt (which proved unsuccessful, as will be seen) to pre-empt criticism and opprobrium from the Anglican Church, Darwin declared,

  I see no good reason why the views given in this volume should shock the religious feelings of any one. It is satisfactory, as showing how transient such impressions are, to remember that the greatest discovery ever made by man, namely, the law of the attraction of gravity, was also attacked by [German philosopher and mathematician Gottfried W.] Leibnitz ‘as subversive of natural, and inferentially, of revealed religion’.28

  [However] … the chief cause of our natural unwillingness to admit that one species has given birth to clear and distinct species, is that we are always slow in admitting great changes of which we do not see the steps. The mind cannot possibly grasp the full meaning of the term of even a million years; it cannot add up and perceive the full effects of many slight variations, accumulated during an almost infinite number of generations.29

  Analogy would lead me one step farther, namely to the belief that all animals and plants are descended from some one prototype.30

  This is the view commonly held today: that life on Earth first appeared about 3.8 billion years ago in the form of a single-celled organism.

  Darwin completed Origin on a note of optimism

  as natural selection works solely by and for the good of each being, all corporeal and mental endowments will tend to progress towards perfection.31

  In other words, as far as evolution was concerned, Darwin saw it as being applicable to the mind, as well as the body.

  Thus, from the war of nature, from famine and death, the most exalted object which we are capable of conceiving, namely, the production of the higher animals, directly follows. There is grandeur in this view of life, with its several powers, having been originally breathed by the Creator into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been and are being evolved.32

  So, surprisingly to Darwin’s way of thinking, his great theory of evolution did not preclude the existence of a ‘Creator’.

  In the autumn of 1864, almost five years after the publication of Origin, Darwin described to Ernst Haeckel, Professor Extraordinarius of Zoology, University of Jena, how he had arrived at his theory.

  As you seem interested about the origin of the Origin & I believe do not say so out of mere compliment, I will mention a few points. When I joined the Beagle as Naturalist I knew extremely little about Natural History, but I worked hard. In South America three classes of facts were broug
ht strongly before my mind: Istly the manner in which closely allied species replace species in going Southward [i.e. from Brazil towards Tierra del Fuego]. 2ndly the close affinity of the species inhabiting the Islands near to S. America to those proper to the Continent. This struck me profoundly, especially the difference of the species in the adjoining islets in the Galapagos Archipelago. 3rdly the relation of the living Edentata [mammals such as sloths, anteaters and armadillos] & Rodentia [rodents] to the extinct species. I shall never forget my astonishment when I dug out a gigantic piece of armour like that of the living Armadillo.

  Reflecting on these facts & collecting analogous ones, it seemed to me probable that allied species were descended from a common parent. But for some years I could not conceive how each form became so excellently adapted to its habits of life. I then began systematically to study domestic productions [i.e. species which had been deliberately bred by man], & after a time saw clearly that man’s selective power was the most important agent. I was prepared from having studied the habits of animals to appreciate the struggle for existence, & my work in Geology gave me some idea of the lapse of past time [i.e. the enormous amount of time which had elapsed since life on Earth began]. Therefore, when I happened to read ‘Malthus on population’ the idea of Natural selection flashed on me. Of all the minor points, the last which I appreciated was the importance & cause of the principle of Divergence.33

  Darwin defined ‘Divergence’ as ‘the tendency in organic beings descended from the same stock to diverge in character as they become modified’.34

  Finally, Darwin summarized his views thus:

  Although much remains obscure, and will long remain obscure, I can entertain no doubt, after the most deliberate study and dispassionate judgement of which I am capable, that the view which most naturalists until recently entertained, and which I formerly entertained – namely, that each species has been independently created – is erroneous. I am fully convinced the species are not immutable; but that those belonging to what are called the same genera are lineal descendants of some other and generally extinct species, in the same manner as the acknowledged varieties of any one species are the descendants of that species. Furthermore, I am convinced that Natural Selection has been the most important, but not the exclusive, means of modification.35

  * * *

  How was Origin received? Darwin told French zoologist and anthropologist J. L. Armand de Quatrefages de Bréau on 5 December 1859 that Lyell, Hooker, Huxley, and physician and naturalist William Benjamin Carpenter, amongst others, had all been converted to his way of thinking in respect of the ‘mutability of species’.36 Four days later Darwin’s cousin, Francis Galton, wrote to congratulate him ‘on the completion of your wonderful volume …’.37 And, on 21 December, Darwin told Asa Gray that

  the 1st Edit [Edition] of 1250 copies was sold on [the] first day, & now my publisher is printing off as rapidly as possible 3000 more copies.38

  Meanwhile, Origin had its detractors. For example, on the very day of its publication, Professor Sedgwick wrote disparagingly to Darwin to say

  I have read your book with more pain than pleasure. Parts of it I admired greatly; parts I laughed at till my sides were almost sore; other parts I read with absolute sorrow; because I think them utterly false & grossly mischievous … .39

  To which, on 26 November 1859, Darwin responded, ‘I cannot think a false theory would explain so many classes of facts, as the theory seems to me to do. But magna est veritas & thank God, prevalebit.’40 Sedgwick was an evangelical Christian but Darwin, in his letter, had demonstrated that he, too, had a good working knowledge of holy scripture: Magna est veritas, etprevalebit (‘great is truth, and it prevails’) being a quotation from the ‘Vulgate’, the commonly used Latin translation of the Holy Bible.41

  Darwin’s faith in his theory was unshakable. What the world now waited for with bated breath was for him to make a pronouncement on whether his theory applied to human beings and, if so, to what extent. The fact that Darwin believed that it did indeed apply to humans, and that he had come to this conclusion well before the publication of Origin, was revealed by him in his autobiography.

  As soon as I had become, in the year 1837 or 1838, convinced that species were mutable productions, I could not avoid the belief that man must come under the same law.42

  He also declared that ‘light would be thrown on the origin of man and his history’ as a result of this book,43 which was ‘no doubt the chief work of my life’.44

  For a full exposition by Darwin of his view on evolution in respect of man, however, the world would be obliged to wait more than a decade, until the publication of The Descent of Man in 1871.

  NOTES

  1. Darwin, Francis, op. cit., p.622.

  2. Darwin, Charles, The Origin of Species, p.x.

  3. Ibid, p.27.

  4. Ibid, pp.41–2.

  5. Ibid, p.55.

  6. Ibid, p.57.

  7. Ibid, p.59.

  8. Ibid, p.72.

  9. Ibid, pp.78–9.

  10. Ibid, p.111.

  11. Ibid, p. 122.

  12. Ibid, p. 131.

  13. Ibid, p. 194.

  14. Ibid, p.224.

  15. Ibid, p.256.

  16. Ibid, p.287.

  17. Ibid, p.293.

  18. Ibid, p.317.

  19. Ibid, p.318.

  20. Ibid, p.320.

  21. Ibid, p.343.

  22. Ibid, p.346.

  23. Ibid, pp.348–9.

  24. Ibid, p.351.

  25. Ibid, p.350.

  26. Ibid, p.423.

  27. Ibid, p.442.

  28. Ibid, p.443.

  29. Ibid, p.444.

  30. Ibid, p.446.

  31. Ibid, p.450

  32. Ibid, p.450.

  33. Darwin to Ernst Haeckel, [after 10] August – 8 October 1864, Cor. 12, p.302.

  34. Darwin, Francis, op. cit., p.57.

  35. Darwin, Charles, op. cit., p.30.

  36. Darwin to J. L. A. de Quatrefages de Bréau, 5 December 1859, Cor.7, p.415.

  37. Darwin to Francis Galton, 9 December 1859, Cor.7, p.417.

  38. Darwin to Asa Gray, 21 December 1859, Cor.7, p.440.

  39. Darwin to Adam Sedgwick, 24 November 1859, Cor.7, p.396.

  40. Darwin to Adam Sedgwick, 26 November 1859, Cor.7, p.404.

  41. Latin Vulgate Bible, 3 Esdras. 4:41.

  42. Darwin, Francis, op cit., p.66.

  43. Ibid, pp.66–7.

  44. Ibid, p.59.

  Chapter 16

  The Great Oxford Debate

  With the onset of the new year work continued apace. On the sixth day of 1860 Darwin enquired of Thomas Bridges, a missionary in the Falkland Islands, as to the body language and facial expressions of the Fuegians and Patagonians. For example, do they

  nod their heads vertically to express assent, and shake their heads horizontally to express dissent? Do they blush … ? Do they sneer … ? Do they frown … ? Do they ever shrug their shoulders to show that they are incapable of doing or understanding anything?1

  Darwin, in a letter of 18 January to Baden Powell, writer on theological topics and Savilian Professor of Geometry at Oxford University, quoted Sir John Herschel, who described the introduction of a new species as ‘a natural in contradistinction to a miraculous process’.2

  In April, wrote Darwin to Lyell,

  I can see no reason whatever for believing in such interpositions [of the Deity] in the case of natural beings, in which strange & admirable peculiarities have been naturally selected for the creature’s own benefit.3

  To Henslow, on 8 May, Darwin declared,

  I can perfectly understand Sedgwick or any one saying that nat. selection does not explain large classes of facts; but that is very different from saying that I depart from [the] right principles of scientific investigation.4

  On 14 May Darwin wrote again to Henslow to say:

  I must thank you from my heart for so generously defending me as far as you could
against my powerful attackers. Nothing which persons say hurts me for long, for I have entire conviction that I have not been influenced by bad feelings in the conclusions at which I have arrived. Nor I have I published my conclusions without long deliberation & they were arrived at after far more study than the [public] will ever know of or believe in. I am certain to have erred in many points, but I do not believe so much as Sedgwick & Co. think.5

  Here, Darwin was implying that although others may have been motivated by ‘bad feelings’ towards him, he entertained no such animosity towards them. This situation would change, however, particularly in respect of one individual, namely Richard Owen.

  Four days later Darwin informed Wallace that he [Darwin] was under the proverbial cosh from his critics.

  The attacks have been heavy & incessant of late. Sedgwick & Prof. [Clark] attacked me savagely at Cambridge [Philosophical Society] But Henslow defended me well, though [he is] not a convert [to Darwin’s theory].- Phillips has since attacked me in [a] Lecture at Cambridge. Sir W. Jardine in [Edinburgh New Philosophical Journal], Wollaston in [Annals and Magazine of Natural History]. A. Murray before [the] Royal [Society] of Edinburgh – Haughton at [Geological Society] of Dublin – Dawson in Canadian [Naturalist] Magazine, and many others.6

  The persons referred to above were William Clark, clergyman and Professor of Anatomy at Cambridge University; John Phillips, Professor of Geology at Oxford University; William Jardine, 7th Baronet, naturalist and founder in 1841 of the Annals and Magazine of Natural History; Thomas Vernon Wollaston, entomologist and conchologist; Andrew Murray, entomologist and botanist and Assistant Secretary to the Royal Horticultural Society; Samuel Haughton, clergyman and paleobotanist, Registrar of the Medical School, Dublin, and John William Dawson, Professor of Geology and Principal of McGill University, Montreal, Canada.