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Darwin Correspondence Project

From P. B. Mason   29 March 1871

Burton on-Trent

March 29— 1871.

My dear Sir,

I have much pleasure in complying with your request.1

I have just seen a young lady aged 17, in no way deformed but possessing considerable personal attractions though now suffering from chlorosis. The family originally consisted of eleven children, now between 2 and 20 years of age— of these four have already died, showing I think that their vitality is below the average.

I examined the back as far down as the lower part of the lumbar region, and found it to be uniformly though not very thickly covered with fine hairs from one third to three quarters of an inch in length. The majority of the hairs lie flat on the skin but 6 or 7 in each square inch project nearly at right angles to the rest. The spinal region, scapulæ and loins were as far as I could judge equally well provided with these appendages. Her sister aged 8 years has quite as much and the mother tells me that the father has still more.

While working at the Hospital for Sick Children in Great Ormond Street2 I frequently saw children with hairy backs, and if you wish for statistics could no doubt ascertain the number say in 1000 children.

Will you allow me to make a suggestion as to the cause of the greater proportion of male infants who are still-born? It is generally considered to depend on the greater size of the male fœtus, this according to Simpson averages half an inch in length and three quarters of an inch in weight more than the female—3 This greater size necessarily causes a greater mortality during parturition both to the mother and child. With sheep also the pelvis of the ewe is frequently so much contracted that delivery is difficult or impossible.

Believe me | Very truly Yours | Philip B. Mason.

C. Darwin Esq.

CD annotations

1.1 I have … children. 4.3] crossed pencil
Top of letter: ‘Dr Duncan4 has probably weighed many children ♀ & ♂.— | Death of Male Children. Sex Selection’ pencil; ‘Yes’ pencil circled pencil; ‘vide’ pencil


In 1866, during a cholera epidemic, Mason was in charge of a temporary Hospital for Children in London, part of the Great Ormond Street Hospital for Sick Children (Lancet, 14 November 1903, pp. 1405–6).
For James Young Simpson’s statistics on the causes and proportion of male and female stillbirths, see Simpson 1844.
In Descent 1: 174, CD had cited James Matthews Duncan on the numbers of children born to younger mothers.


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

Simpson, James Young. 1844. Memoir on the sex of the child as a cause of difficulty and danger in human parturition. Edinburgh Medical and Surgical Journal 62 (1844): 387–439.


More details on children with hairy backs;

reasons for greater mortality rate of male children.

Letter details

Letter no.
Philip Brookes Mason
Charles Robert Darwin
Sent from
Source of text
DAR 90: 72–3
Physical description
3pp †

Please cite as

Darwin Correspondence Project, “Letter no. 7641,” accessed on 25 September 2021,

Also published in The Correspondence of Charles Darwin, vol. 19