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Darwin Correspondence Project

To G. H. K. Thwaites   13 February [1868]1

Down. | Bromley. | Kent. S.E.

Feb. 13th

My dear Thwaites

I wrote a little time ago asking you an odd question about Elephants, & now I am going to ask an odder.2

I hope that you will not think me an intolerable bore.— It is most improbable that you could get me an answer, but I ask on mere chance.— Macacus silenus has a great mane of hair round neck, & passing into large whiskers & beard, now what I want most especially to know is, whether these monkeys when they fight in confinement (& I have seen it stated that they are sometimes kept in confinement) are protected from bites by their mane & beard.3

Anyone who watched them fighting would I think be able to judge on this head. My object is to find out with various animals how far the mane is of any use, or a mere ornament.—4 Is the male Macacus silenus furnished with longer hair than the female about the neck & face? As I said it a hundred or a thousand to one against you finding out anyone who has kept or keeps these monkeys in confinement.—

Excuse me if you can, & believe me | Yours very sincerely | Ch. Darwin


The year is established by the relationship between this letter and the letter to G. H. K. Thwaites, 31 January [1868].
Thwaites forwarded CD’s query to Samuel Owen Glenie; see enclosure to letter from G. H. K. Thwaites, 22 July 1868. Macacus silenus (now Macaca silenus) is commonly known as the liontail macaque or wanderoo (see Kavanagh 1983).
CD concluded in Descent 2: 312 that ‘crests and tufts of hair’ on the heads of monkeys were probably acquired through sexual selection ‘exclusively as ornaments’.


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

Kavanagh, Michael. 1983. A complete guide to monkeys, apes and other primates. London: Cape.


Asks whether mane in male of Macacus silenus protects it from bites or is merely ornamental.

Letter details

Letter no.
Charles Robert Darwin
George Henry Kendrick Thwaites
Sent from
Source of text
American Philosophical Society (Mss.B.D25.341)
Physical description
ALS 3pp

Please cite as

Darwin Correspondence Project, “Letter no. 5872,” accessed on 12 September 2023,

Also published in The Correspondence of Charles Darwin, vol. 16