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Darwin Correspondence Project

To the Spectator   11 January 1873

(To the Editor of the “Spectator.”)

Sir,—

Any one interested in the subject to which you allude at p. 42 of your last number, namely, the relative importance in causing modifications of the body or the mind, on the one hand of habit or of the direct action of external conditions, and on the other hand of natural or artificial selection, will find this subject briefly discussed in the second volume (pp. 301–315) of my “Variation of Animals and Plants under Domestication.”1 I have there given a considerable body of facts, chiefly in relation to acclimatisation, which presents the greatest difficulty in the present question; and it may be inferred from these facts, firstly, that variations of a directly opposite nature, which would be liable either to preservation or elimination through natural selection, not rarely arise in organisms long exposed to similar conditions; and secondly, that habit, independently of selection, has often produced a marked effect. But it is most difficult, as I have insisted in many of my works, though in some cases possible, to discriminate between the results of the two processes. Both tend to concur, for the individuals which inherit in the strongest manner any useful habit will commonly be preserved.

Take, as an instance, the fur of quadrupeds, which grows thickest in the individuals living far north; now there is reason to believe that weather acts directly on the skin with its appendages, but it is extremely difficult to judge how much of the effect ought to be attributed to the direct action of a low temperature, and how much to the best protected individuals of many generations having survived during the severest winters. I have made many observations and collected many facts, showing the potent influence of habit and of the use or disuse of parts on organic beings; but there are numberless peculiarities of structure and of instinct (as in the case of sterile neuter insects)2 which cannot be thus accounted for. He would be a bold man who would attempt to explain by these means the origin of the exsertile claws and great canine teeth of the tiger; or of the horny lamellæ on the beak of the duck, which are so well adapted for sifting water. Nor would anyone, I presume, even attempt to explain the development, for instance, of the beautifully plumed seeds of the dandelion,3 or of the endless contrivances which are necessary for the fertilisation of very many flowers by insects, through gradually acquired and inherited habit, or through the direct action of the external conditions of life.—

I am, Sir, &c., | Charles Darwin.

Down, Beckenham, Kent, Jan. 11, 1873.

Footnotes

In the Spectator, 11 January 1873, pp. 42–4, there was a discussion, headed ‘Dr Carpenter on mental acquisition and inheritance’, of the first part of a paper by William Benjamin Carpenter in the Contemporary Review (Carpenter 1872–3). The author wrote, ‘Mr. Darwin’s theory suggests that adaptation takes place by the appearance of varieties in all directions, and then the disappearance of varieties which are unfavourable to the actual conditions of existence’, and argued that it was hard to explain adaptation to changed conditions within one generation on this theory alone.
See Origin, pp. 236–42.
See Origin, p. 77.

Summary

Discusses two factors possibly causing modification of body or mind of an organism; habit and direct action of external conditions on the one hand, and selection, natural or artificial, on the other; considers their relative importance.

Letter details

Letter no.
DCP-LETT-8731
From
Charles Robert Darwin
To
Spectator
Sent from
Down
Source of text
Spectator, 18 January 1873, p. 76.
Physical description
draft 3pp

Please cite as

Darwin Correspondence Project, “Letter no. 8731,” accessed on 12 December 2017, http://www.darwinproject.ac.uk/DCP-LETT-8731

Also published in The Correspondence of Charles Darwin, vol. 21

letter