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Darwin Correspondence Project

From Lionel Ashburner   25 June 1871

Kandesh Magistrates Camp Kandesh

June 25/71


Allow me to contribute the following facts in support of your theory of selection.

The males of the small brown monkey of Western India are in the habit of castrating the young males, a〈nd〉 I believe the same thing is done by the large Langoors but I cannot state this as a fact, for only on one occasion have I observed a male monkey of this kind without testicles1   Natives who have had good opportunities of observing their habits assure me that castration is practised by both kinds of monkeys— There can be no doubt of it with regard to the small monkey. In some places (at Sapt Sring2 for instance, they are so tame that they may be observed from 〈a〉 distance of a yard or two, and I have never seen more than two or three males with testicles in each troop the testicles of all the others appearing to have been entirely removed at a very early age. I mentioned this fact to a friend who had been for some years in America   he told me that the American Grey Squirrel3 was in the habit of castrating the young males— When serving in Gujarat some years ago natives assured me that the wild asses of Kulch castrated the superfluous young males of the herds but I was never able to verify this by personal observation4

Tigers destroy the young males an〈d this〉 is no doubt the reason why the tige〈r〉 〈after〉 breeding leaves the jungles. [her] cubs may often be found in places where there is hardly any cover. I have had many opportunities of observing the destruction of young male tigers by the old male.5 There are usually three or four females to each male tiger and he has been developed by selection to a size nearly a third larger than the female but the only other respect in which he differs from the female is in the greater quantity of hairs about the neck.

Hogs6 also are in the habit of killing the young males, it is not unusual when hunting for the beaters to pick up the bodies of young males which have 〈    〉 been killed.

During many years spent in the jun〈gles〉 of India I have recorded observations which confirm your theories but as it is unnecessary to accumulate evidence, I will not trouble you with them—

Yours very truly | L. Ashburner | Magistrate of Kandesh—

I am sorry I cannot give you the scientific names of the monkeys I allude to


The most common small brown monkey in India is the rhesus macaque (Macaca mulatta). Indian langurs are in the genus Semnopithecus.
Sapt Sring is at Hemkund Sahib in the Chamoli district, Uttarakhand on a glacial lake in the Himalayas of north-west India; it is now an important Sikh holy place.
The gray squirrel is Sciurus carolinensis.
The Indian wild ass (Equus khur) inhabits the Kutch district of Gujarat state in western India.
The Indian or Bengal tiger is Panthera tigris tigris. CD remarked that tigers were not social and did not feel sympathy for other tigers except their own young in Descent 2d ed., p. 106.
The Indian boar is Sus scrofa cristatus.


Gives examples of animal species in which adult males castrate or kill younger males.

Letter details

Letter no.
Lionel Robert (Lionel) Ashburner
Charles Robert Darwin
Sent from
Source of text
DAR 159: 115
Physical description
4pp damaged

Please cite as

Darwin Correspondence Project, “Letter no. 10551,” accessed on 19 September 2021,

Also published in The Correspondence of Charles Darwin, vol. 24 (Supplement)