The Complete Work of Charles Darwin Online

RECORD: Darwin, C. R. 1879. [Quote from a lost 1875 letter to Arthur Nicols]. In A. Nicols, Intellect in brutes. Nature. A Weekly Illustrated Journal of Science (20 February): 365.

In 1875 Arthur Nicols (1840-1891), a writer and naturalist living in Australia, wrote to Darwin about a case of rats gnawing through lead pipes to drink the water. ([before 10 Nov. 1875] Correspondence vol. 23, p. 446-7) Darwin replied but the letter has never been found (until now). On 10 November 1875 Nicols wrote back to Darwin "You, in what you term "old age" have given no doubt the true solution of the case of the rats with the leaden pipe. They heard the trickling water (as you say) no doubt, and bored into the lead until they reached it. But this testifies to their intelligence and experimental knowledge, I venture to believe." (10 Nov. 1875 Correspondence vol. 23, p. 448)

Almost four years later, Nicols wrote a letter to Nature in which he recounted the case of rats gnawing pipes and quoted from the now lost Darwin letter: "I cannot doubt about animals reasoning in a practical fashion. The case of rats is very curious. Do not they hear the water trickling?" Nature (20 February): 365. But this was not the end of the matter.

On 27 February George Henslow wrote to Nature (vol. 19, p. 385) with scepticism about Nicols' case being one of true reasoning in rats. On 6 March Nicols' reply to Henslow was published in Nature. (p. 409) On 13 March another reply by Nichols' on "intellect in brutes" to letters from Henslow and Henry Muirhead was published. (p. 433) On 20 March letters from W. P. Buchan and Muirhead were published on matter. (p. 458). Buchan was still sceptical but Muirhead (p. 460) now seemed more convinced. R. Morten Middleton also sent a letter, convinced of rats gnawing water pipes. A week later Darwin sent an account of rats gnawing through water casks on ships. (p. 481, 'Rats and water-casks', F1785)

The editors of Nature wrote the same week: "We have received so many letters on this subject that we are compelled to content ourselves with giving the following extracts". And there were many. (pp. 496-7) Another correspondent wrote of a case of gnawed water casks on 10 April. (p. 529)

On 1 May the editors of Nature again quoted from some of "several additional letters which we have received on this subject". (vol. 20, p. 21) Then on 5 June 1879 the editors wrote: "INTELLECT IN BRUTES. Now that the discussion on this subject in NATURE seems to be running dry, perhaps a few concluding remarks by one who has not hitherto taken any part may be admitted." (p. 122) There followed an article (pp. 122-5) by George J. Romanes which well summarized the debate and added many further examples of animal intelligence, his particular area of interest. Unsurprisingly, he concluded with the Darwinian view that also in intelligence and reasoning, the difference between man and animals was one of degree, not kind. Which is exactly how the 'debate' began when Nicols opened his first piece on 20 February: "The following case will perhaps interest those who believe that the reasoning faculty in man and animals differs in degree only, and is essentially the same in kind." Further contributions on intelligent gnawing rats occasionally appeared for some time.

See also the published 20 March 1873 letter from Darwin which discussed the purported ability of cats to return home from long distances by smell, which Nicols doubted. Nicols, Natural history sketches, 1885, p. 52 (F2281).

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Intellect in Brutes

The following case will perhaps interest those who believe that the reasoning faculty in man and animals differs in degree only, and is essentially the same in kind. Some years ago a plumber told me that he had, on several occasions, been called in to examine into the cause of leakage of water-pipes under the flooring of houses, and had found that the rats had gnawed a hole in the leaden pipe to obtain water, and that great numbers of them had made it a common drinking-place, as evidenced by the quantity of dung lying about. The plumber brought me a piece of leaden pipe, about 3/4 inch in diameter and 1/8 inch in thickness, penetrated in two places, taken by himself from a house on Haverstock Hill. There are the marks of the incisors on the lead, as clear as an engraving; and a few hairs and two or three of the rats' vibrissæ have been pinched into the metal in the act of gnawing it. This crucial proof of brute intelligence — a rat will not drink foul water — interested me so much, that I ventured to send an account of it to Dr. Chas. Darwin, asking his opinion on the means by which the rats ascertained the presence of water in the pipe. To this he replied: "I cannot doubt about animals reasoning in a practical fashion. The case of rats is very curious. Do not they hear the water trickling?" It may be conceded that this explanation is the most probable, and if it be the true one we have an example of an animal using his senses to obtain the data for a process of reasoning, leading to conclusions about which he is so certain that he will go to the trouble of cutting through a considerable thickness of lead. Obviously man could do no more under the same conditions. ARTHUR NICOLS

Citation: John van Wyhe, ed. 2002-. The Complete Work of Charles Darwin Online. (http://darwin-online.org.uk/)