To A. R. Wallace 5 May 1
Down. | Bromley. | Kent. S.E.
My dear Wallace
I am afraid I have caused you a great deal of trouble in writing to me at such length. I am glad to say that I agree almost entirely with your summary, except that I shd put sexual selection as an equal, or perhaps as even a more important, agent in giving colour than natural selection for protection.2 As I get on in my work I hope to get clearer & more decided ideas. Working up from the bottom of the scale I have as yet only got to fishes.3 What I rather object to in yr articles is that I do not think any one wd infer from them that you place sexual selection even as high as No 4 in yr summary:4 It was very natural that you shd give only a line to sexual selection in the summary to the West. Rev., but the result at first to my mind was that you attributed hardly any thing to its power.5 In your penultimate note you say “in the great mass of cases in which there is great differentiation of colour between the sexes, I believe it is due almost wholly to the need of protection to the female”.6 Now looking to the whole animal kingdom I can at present by no means admit this view; but pray do not suppose that because I differ to a certain extent, I do not thoroughly admire your several papers & yr admirable generalization on bird’s nests. With respect to this latter point, however, although following you, I suspect that I shall ultimately look at the whole case from a rather different point of view.7
You ask what I think about the gay-coloured females of Pieris; I believe I quite follow you in believing that the colours are wholly due to mimicry; & I further believe that the male is not brilliant from not having received thro’ inheritance colour from the female, & from not himself having varied; in short, that he has not been influenced by selection.8
I can make no answer with respect to the elephants. With respect to the female reindeer I have hitherto looked at the horns simply as the consequence of inheritance not having been limited by sex.9
Your idea about colour being concentrated in the smaller males seems good, & I presume that you will not object to my giving it as yr suggestion.10
Believe me my dear Wallace with many thanks | Yours very sincerely | Ch. Darwin
Criticism of ARW for too little esteem of the role of sexual selection as agent in giving colour.
Response to other topics.
Please cite as
Darwin Correspondence Project, “Letter no. 6161,” accessed on 24 January 2017, http://www.darwinproject.ac.uk/DCP-LETT-6161