The Advantages of Obscurity: Charles Darwin's Negative Inference from the Histories of Domestic Breeds

Summary

In The Origin of Species, Charles Darwin famously accounted for the lack of fossil evidence in support of species evolution on the grounds that the fossil record is naturally incomplete. This essay examines a similar argument that Darwin applied to his analogy between natural and artificial selection: the scarcity of data about the historical backgrounds of domestic breeds was the natural by-product of an extremely gradual change process. The point was to enhance the ability of the artificial selection analogy to suggest that nature's species had undergone a similar transformation. Darwin did not depend on this negative inference alone, however, for in his writings he included whatever information he could find about the actual histories of particular breeds. A comparison with Darwin's treatment of the fossil record suggests the reasonableness of this combined use of opposite kinds of evidence to establish a single point. The comparison also suggests the unique qualities of negative inference as applied to the breeding analogy.

Notes

¹M. Rudwick, ‘Darwin and Glen Roy: A “Great Failure” in Scientific Method?’, Studies in History and Philosophy of Science, 5 (1974), 97–185, 124–28, 164–67; H.E. Gruber, Darwin on Man (Chicago, 1974), 107; J. Browne, Charles Darwin: Voyaging (New York, 1994), 376–78, 438, 440.

²C. Darwin, On the Origin of Species (1859, Cambridge, MA, 1964), ch. 9.

³For examinations of Darwin's breeding analogy, see J.F. Cornell, 1984, ‘Analogy and Technology in Darwin's Vision of Nature’, Journal of the History of Biology, 17: 303–44; L.T. Evans, 1984, ‘Darwin's Use of the Analogy between Artificial and Natural Selection’, Journal of the History of Biology, 17: 113–40; R.A. Richards, 1997, ‘Darwin and the Inefficacy of Artificial Selection’, Studies in History and Philosophy of Science, 28: 75–97; and S. Sterrett, 2002, ‘Darwin's Analogy between Artificial and Natural Selection: How Does it Go?’ Studies in History and Philosophy of Biological and Biomedical Sciences, 33: 151–68.

⁴The various components of Darwin's argument in the Origin are analysed in C.K. Waters, 2003, ‘The Arguments in the Origin of Species’, in M.J. S. Hodge and G. Radick, eds, The Cambridge Companion to Darwin (Cambridge, 2003), 116–39. Pp. 123–27, especially, deal with Darwin's use of the breeding analogy.

⁵C. Darwin (note 2, 1859), 35.

⁶C. Darwin (note 2, 1859), 40.

⁷C. Darwin, Variation of Animals and Plants under Domestication, 2 vols (1868; New York, 1988), II: 200, emphasis added.

⁸See S. Herbert, ‘The Place of Man in the Development of Darwin's Theory of Transmutation, Part II’, Journal of the History of Biology, 10 (1977), 155–227; and J. Hodge, ‘The Notebook Programmes and Projects of Darwin's London Years’, in M.J.S. Hodge and G. Radick, eds, The Cambridge Companion to Darwin (Cambridge, 2003), 40–86.

⁹The larger innovation was the distinction between ‘methodical’ and ‘unconscious’ selection, which made its first appearances in Darwin's unpublished ‘Pencil Sketch’ of 1842 and ‘Essay’ of 1844. See C. Darwin, The Foundations of the Origin of Species: Two Essays Written in 1842 and 1844 (New York, 1986), 2–3, 51–53; also: Darwin (note 2, 1859), 34–39.

¹¹J. Sebright, The Art of Improving the Breeds of Domestic Animals (London, 1809), 11; J. Wilkinson, Remarks on the Improvement of Cattle, etc. in a letter to Sir John Sauders Sebright (Nottingham, 1820), 32–33, emphasis added. We can date Darwin's initial reading of Sebright and Wilkinson in late May of 1838, according to C. Darwin, Charles Darwin's Notebooks, 1836–1844, eds. P.H. Barrett, et al (Cambridge, 1987), C133 (‘C’ stands for the ‘C’ notebook in the series). M. Ruse, ‘Charles Darwin and Artificial Selection’, Journal of the History of Ideas, 36 (1975), 339–50, 345, argues that Darwin annotated these pamphlets on the first reading, although this is difficult to verify. Further details about Darwin's reading of Sebright and Wilkinson appear in Ruse 1975, and Evans (note 3, 1984), 123–24, 131.

¹⁰C.J. Bajema, ed., Artificial Selection and the Development of Evolutionary Theory (Stroudsburg, PA, 1982), 68–70; Evans (note 3, 1984), 122–23.

¹²Sebright 1809, Darwin Pamphlet Collection, G63, Darwin Collection, Cambridge University Library (hereafter CUL). Darwin added his own comment (written twice on the same page) beside the Wilkinson text (note 11): ‘A constant principle of change’. Darwin Pamphlet Collection, G62, CUL, emphasis in the original.

¹³Darwin found a similar problem when he tried to assess Yarrell's hypothesis that the older of two crossed breeds exerted the dominant influence on the character of the offspring, for Yarrell could give no real evidence as to which of the breeds was older. See Darwin's Notebooks, C121 (note 11, 1987).

¹⁴Darwin (note 11, 1987), 429, n. 113-3. Darwin (note 6, 1986, 55–77) fleshed out this point concerning Dahlias in his 1844 ‘Essay’, in the section entitled ‘Whether Our Domestic Races have Descended from One or More Wild Stocks’. He argued for the ‘probable’ common origins of many breeds, based on what was certain in a few cases. He admitted that this was a matter of inference: ‘Whether we consider our races as the descendants of one or several wild stocks, we are in far the greater number of cases equally ignorant what these stocks were’. Darwin (note 2, 1859, 16–19) repeated the same essential material in the Origin.

¹⁵Rudwick (note 1, 1974), 124–28, 164–65.

¹⁷The sources of this analogy in Lyell's writings are examined in Darwin (note 9, 1986), 21, n. 17; and in Darwin (note 11, 1987), 352–53n. Darwin made an early note on the imperfection of the fossil record, which preceded his (late June) Glen Roy trip by several weeks: ‘The areas of subsidence marked out by animals of same genera is not equal to areas of elevation: marked out by existence of elevated (extinct?) genera of shells’. Darwin (note 11, 1987), C220; see also ibid., T63.

¹⁶Darwin's paper was ‘Observations on the Parallel Roads of Glen Roy’ (1839).

¹⁸Darwin (note 6, 1986), 18–20, 106–8.

¹⁹Rudwick (note 1, 1974), 129, 173–74.

²⁰For a detailed analysis of Darwin's early theorizing, see M.J.S. Hodge and D. Kohn, ‘The Immediate Origins of Natural Selection’, in D. Kohn, ed. The Darwinian Heritage (Princeton, 1984), 185–206.

²¹Darwin (note 9, 1986), 2, 51–52.

²²Quoted in P.J. Vorzimmer, ‘An Early Darwin Manuscript: The “Outline and Draft” of 1839’, Journal of the History of Biology, 8 (1975), 191–217, 215. For an analysis of this source (including a revised dating of sometime between 1840 and 1844), see D. Kohn et al., ‘New Light on The Foundations of the Origins of Species: A Reconstruction of the Archival Record’, Journal of the History of Biology, 15 (1982), 419–42.

²³We can date this and other readings from C. Darwin, ‘Darwin's Reading Notebooks’, The Correspondence of Charles Darwin, eds., F. Burkhardt et al. (Cambridge, 1988), IV: 434–501. (The reference to W. Youatt, Cattle: Their Breeds, Management, and Diseases (London, 1834), is on p. 459.)

²⁴Youatt (note 24, 1834), 115. Similar remarks appear ibid., 116, 128, 166, 190, 199, 226. Darwin would use examples from this work by Youatt in his Variation Under Domestication. Darwin (note 7, 1868), II: 200.

²⁵C. Darwin, Charles Darwin's Marginalia, eds., M. Di Gregorio and N. Gill, 2 vols (New York, 1990), I: 885, 886. Darwin later found a similar thesis in David Low's Domesticated Animals of the British Islands (London, 1845), 188. Low considered whether Cotswold sheep had always been long-wooled, dating from their inception. Some observers had arrived at an affirmative answer in light of the absence of any memory of a change in this condition. Darwin double-scored the margin of the page next to Low's comment on this hypothesis:

But we know how quickly the memory of such events is effaced, and that changes as great as that in the Cotswold sheep have occurred in all parts of the kingdom, without our having the means of obtaining any account of them after the lapse of a short period.

Darwin then added his own summary: ‘Remarks how soon a breed in any country changes with no record of it’. According to Darwin's list of ‘books read’ (Darwin, note 20, 1988, 470), the dating of Darwin's original reading of Low was January of 1846.

²⁶It is difficult to know exactly when Darwin wrote some of the reference notes in the backs of the books he read: the colour of ink used sometimes indicates a latter addition. Notes made in the page margins, however, presumably were made on the first reading. N. Gill, Personal communication, 2004; Darwin (note 25, 1990), xii.

²⁷For the records of these writers in Darwin's reading list, see Darwin note 24, 1988, 456, 458, 461, 462.

³⁰T. Carlyle, Critical and Miscellaneous Essays, 4 vols (London, 1839), II: 86–87.

²⁸On Darwin's ambivalence about Carlyle and his writings, see C. Darwin, Correspondence of Charles Darwin, eds. F. Burkhardt, et al. (Cambridge, 1985–), II:129, 236, 155; and C. Darwin, The Autobiography, ed. N. Barlow (1958; New York, 1993), 112–14. See also: J. Browne, Charles Darwin: Voyaging (New York, 1994), 366–67.

²⁹J.W. Burrow, ‘Images of Time: from Carlylean Vulcanism to Sedimentary Gradualism’, in S. Collini et al., eds., History, Religion, and Culture: British Intellectual History, 1750–1950 (Cambridge, 2000), 198–223, 205–10, 219–20, notes two sets of geological images in Carlyle's works: ‘volcanic’ imagery in discussions of the French Revolution, but also references to slow and unobserved development. While Burrow emphasizes the former, I note the frequent occurrence of the latter.

³¹T. Carlyle, Critical and Miscellaneous Essays, 4 vols (London, 1839), II: 170, 183. Carlyle quoted this example from an anonymous work about German civilization.

³⁴D. Hume and S. Smollett, History of England, 6 vols (London, 1834), VI: 127, emphasis added. This material appeared in an appendix to Hume's chapter on James I.

³²Darwin (note 24, 1988), 462.

³³On the political orientations of these writers, see P.J. Bowler, The Invention of Progress: The Victorians and the Past (New York, 1989), 22, 41.

³⁵Darwin (note 24, 1988), 461.

³⁶On the pattern of accidental discoveries in Darwin's work, see Herbert (note 8, 1977), 215–17, 226. Darwin added a note in his list of ‘books to be read’, likely after he read Hallam's book: ‘Fabricius (very old) has written on language of Brutes; referred to by Hallam’. Darwin (note 23, 1988), 443. The discussion of Fabricius appears in H. Hallam, Introduction to the Literature of Europe in the Fifteenth, Sixteenth, and Seventeenth Centuries, 4 vols (Paris: 1837–1839), III: 31–33. Hallam thus suggesting a naturalistic explanation of the origin of language. Notebook entries showing Darwin's interest in language include: Darwin (note 11, 1987), N18, N20, N31, N39, N65, N107, N127, and OUN5.

³⁷Darwin (note 2, 1859), 40.

³⁸Hallam (note 37, 1837–1839), I: 18. Here, I supplement the discussion of this analogy in S.G. Alter, Darwinism and the Linguistic Image (Baltimore, 1999), 22–23.

³⁹Hallam (note 37, 1837–1839), I: 33–34, 21, emphasis added.

⁴¹Darwin (note 2, 1859), 40, emphasis added.

⁴⁰Darwin declared in his reading notebook: ‘There are some few references at end of Hallam’. Darwin (note 24, 1988), 461. Unfortunately, Darwin's copy of Hallam's book has been lost.

⁴²Darwin had mentioned in his notebook (Darwin, note 25, 1990), D42, that naming was a mark of the perceived full emergence of a breed: ‘Mr. Drinkwater thought that a ‘first blood’ [i.e. pure-blooded] animal must have gone on for many years, before deserves <name> to be so called’.

⁴³Darwin (note 2, 1859), 310–11.

⁴⁴Hallam (note 37, 1837–1839), I: 34. Here, I supplement Alter (note 38, 1999), 26–28, which attributes the language element in ‘Lyell's metaphor’ to a passage from Lyell's Principles of Geology (1831–1833).

⁴⁵The lawyer and geologist Joshua Toulmin Smith supposed that Darwin's illustration referred to Titus Livy's multi-volume History of Rome. J.T. Smith to C. Darwin, 6 January 1860, in The Correspondence of Charles Darwin, Frederick Burkhardt, Duncan Porter, et al (eds), vol. 8 (Cambridge, 1993), 22–23, note 3.

⁴⁶In probably a unique combination, Darwin at one point brought together in one passage the fossil record and the histories of breeds, linking these in an imagined future scenario:

We shall, perhaps, best perceive the improbability of our being enabled to connect species by numerous, fine, intermediate, fossil links, by asking ourselves whether, for instance, geologists at some future period will be able to prove, that our different breeds of cattle, sheep, horses, and dogs have descended from a single stock or from several aboriginal stocks. Darwin (note 2, 1859), 298–99.

⁴⁷Darwin (note 7, 1868), I: 36–38; II: 169, 171, 200, 202.

⁴⁸Darwin reported on this research in the Origin (note 2, 1859), 20–29, and in Variation (note 7, 1868), ch. 6.

⁴⁹Darwin quoted in J. Secord, ‘Nature's Fancy: Charles Darwin and the Breeding of Pigeons’, Isis 72 (1981), 163–86, 183. Secord (ibid., 184) notes that there were gaps in the pedigrees of pigeon breeds due to the competitive secretiveness among London's ‘fanciers’. There is no evidence, however, that Darwin regarded this lack of data as analogous, as Secord suggests, to the gaps in the fossil record.

⁵⁰Darwin (note 7, 1868), I: 166–88; II: 202.

⁵¹Darwin had made the same argument in his 1844 ‘Essay’, prior to doing his work with pigeons. He emphasized the importance of the issue at that time: ‘As far as we admit the difference of our races to be due to the differences of their original stocks, so much must we give up the amount of variation produced under domestication’. Darwin (note 9, 1986), 57.

⁵²Darwin (note 7, 1868), II: 200.

⁵³A similar charge appears in P. Johnson, Darwin on Trial (Downers Grove, IL, 1991).