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Darwin Correspondence Project

To George Harris   27 April 1875

Down, | Beckenham, Kent. | Railway Station | Orpington. S.E.R.

Ap 27 75

Dear Sir

I know of no facts making it probable that animals perceive any qualities which are not perceived by us, tho’ they may do so in a higher degree. A sense of direction perhaps forms an exception, though this is doubtful. I do not believe that any animal knows what herbs are poisonous, except through experience during former generations by which an inherited association or instinct has been acquired against any particular herb. When sheep are turned out into a new country, they often eat poisonous plants, but it is said, at least in parts of Australia they gradually learn to avoid them.1

I wish I could give a fuller answer, but have not time to reflect on the subject

Dear Sir | yours faithfully | Ch. Darwin


No letter from Harris to CD on this subject has been found; however, Harris had sent CD proof-sheets of his book A philosophical treatise on the nature and constitution of man (Harris 1876; see Correspondence vol. 22, letter from George Harris, 10 February 1874). The book contained a discussion of the sense perception of animals, and Harris cited CD’s letter in his discussion of the view that animals resorted to particular herbs in the event of sickness and could detect and avoid poisons, ‘probably owing to the great acuteness and perfection of their sensorial organs’ (Harris 1876, 2: 253). In Harris 1876, 1: 197, he also cited Descent 1: 36 as support for his view that animals were in their highest state of perfection in the wild because they instinctively avoided poisons, while domestic animals often ate poisonous herbs.


Correspondence: The correspondence of Charles Darwin. Edited by Frederick Burkhardt et al. 27 vols to date. Cambridge: Cambridge University Press. 1985–.

Descent: The descent of man, and selection in relation to sex. By Charles Darwin. 2 vols. London: John Murray. 1871.

Harris, George. 1876. A philosophical treatise on the nature and constitution of man. 2 vols. London: George Bell & Sons. Cambridge: Deighton, Bell, & Co.


Briefly answers GH’s query whether animals can perceive any qualities unperceived by man.

Please cite as

Darwin Correspondence Project, “Letter no. 9953,” accessed on 24 November 2020,

Also published in The Correspondence of Charles Darwin, vol. 23