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Darwin Correspondence Project

From John Downing   29 January 1874

Ashfield, | Fermoy.

Janyr. 29th. 1874

My dear Sir/

I regret to say that I have not been able to find out Lord Spencer’s letter on sex breeding.1

I have communicated with several gentlemen and have asked their opinions upon the question referred to in that letter.

The reply of Mr. Grove,2 an experienced breeder of cattle and a man of acute perception, is enclosed.

He admits that there have been families which produced offspring principally of one sex, yet seems to think, notwithstanding, that the quality is not hereditary.

Mr. Jones, another old breeder, tells me that the “Lupine” tribe which he has had for over forty years—bred all through an excess of females.3

He also expresses an opinion (the truth of which I much doubt) that a young bull will get more heifer than bull calves.

In proof of this assertion he cites but a single case, while there have been several to the contrary in well known herds.

At Col. Townley’s the famous bull “Royal Butterfly” got, during his early years, nearly all male offspring: while when he was older the bulk of his stock were heifers.4

This latter instance would appear to bear out views expressed to me by some that the more vigorous parent will often stamp the sex; but it would militate against any supposed possession by cows in general of the power to transmit this quality of breeding in excess calves of one sex.

That some families have this specialty I fully believe, and that they transmit it from generation to generation; but I think they are by no means common.

In my own herd of cattle there was but one tribe that I could adduce as an example, tho’ I have individual cows of different families which never bred any but of one sex.

Some years ago there was a theory started that the sex may be regulated at pleasure according to time of service of the female— if early in the period—produce female— if late—male.

This was tried in several herds and proved false.

I have known a closely bred Booth family of shorthorns which for several generations had been breeding bulls in excess.5 A female of it was put to a bull of different blood and produced a heifer which bred several of her own sex—and these latter in their turn bred a majority of heifer calves.

I hope to get some further information & to communicate it to you during the next week.

I remain, | my dear Sir, | Yours very faithfully | John Downing.


Castle Grove | Ballymaleel | Letterkenny

Janry 19/74

My dear Sir

The proportion of the sexes in all animals & even in vegetables is a wonderful mystery, & I think it very unlikely that we shall ever arrive at a knowledge of the operating cause of it, or of any physical law governing the subject. In the human race the male births are undoubtedly more numerous than the female, in the proportion, it is said, of somewhere about 106 to 100, in cattle & sheep, I think, the male births also are slightly more numerous, but in what proportion I do not know.

It is quite true that some individual animals & even some families in Shorthorns have produced more male than female offspring; & others, vice versa, but there seems nothing extraordinary in this, it would seem more extraordinary, that is, less in accordance with the general law of probability, if each animal produced exactly the same number of males as females, or produced them in the same proportion as that in the agregate of the species, whatever that proportion might be. Suppose a large number of men were to toss up a penny piece—heads or tails—each man taking a limited number of tosses, say half a dozen, the ratio of heads to tails turned up would approach very nearly to equality, but though each man’s chances would be equal, it would be very extraordinary indeed, if some men did not turn up more of one kind than of the other, & if there were an advantage in turning up one kind, some men would be said to be in good luck, some in bad. Possibly some individuals might turn up all heads, some all tails, but if any man turned up all heads, say, in the six tosses, the probability of his turning up a head the seventh time would by no means be affected by it, his chance of doing so would be exactly the same as when he began to throw, & would be represented by 12. Until we know the causes of the proportion of males & females, which we are not likely to know, we have nothing to guide us in any attempt to forecast birth but the common doctrine of chances, derived from numerical statistics.

If a cow had had half a dozen heifer calves in succession I would not on that account back her with odds to have a heifer calf at her next calving.

I have seen lately in the papers articles on breeding in & in, and the late Tom Barnes’ views greatly misrepresented,6 I have had some letters from him on the subject, one in particular, which I cannot now lay my hand on in which he brings me to task for asserting (in my paper quoted by Carr) that there was a limit to breeding in & in, as he Barnes denied that there was any limit whatever to doing so with advantage, I replied to him in a letter which I would have asked him to publish or send to one of the papers, but shortly after I wrote he met with some family misfortunes which put an end to the matter, as the poor fellow was greatly depressed, but a more out & out in & in breeder I never knew.

I had no idea that Carr was going to quote from a letter of mine that appeared in the Mark Lane until his book was in the hands of the printers, for my opinion on the subject had been greatly modified and I should have liked to have revised the article7

Very truly yours | J G Grove


No letter by CD enquiring about this subject has been found. The last extant letter from Downing is that of 13 November 1873 (Correspondence vol. 21). John Charles Spencer was well known for his role in developing the shorthorn breed of cattle in England (ODNB).
James Grove Wood Grove.
In cattle breeding, ‘tribe’ referred to a female lineage, so the Lupine tribe would have included all the females descended from the shorthorn heifer Lupine. John Hawtry Jones of Mullinabro, Waterford, Ireland, introduced the first Lupine to his herd in 1830 (Sinclair 1907, pp. 554–5).
Charles Towneley’s work as a breeder is described in Sinclair 1907, pp. 167–71.
For more on the Booth herds, see Sinclair 1907, pp. 97–133. Thomas Booth originated the Booth strain, and his sons, John and Richard, developed it further on different estates.
Thomas Barnes had argued in 1854 that the inexperienced breeder should be wary of crossing, but in 1859 decided to infuse fresh blood into his herd after careful consideration (Sinclair 1907, pp. 521–2). The recent articles referred to have not been identified.
William Carr quoted remarks by Grove (referred to as Mr Wood), made in a letter of 1864 to the Mark Lane Express and Agricultural Journal, in his book on shorthorn cattle (Carr 1867, pp. 104–10).


On proportion of sexes in births of cattle; variations in families. Encloses a letter from J. G. Grove on proportions of sexes in animals.

The limitation of inbreeding.

Letter details

Letter no.
John Downing
Charles Robert Darwin
Sent from
Ashfield House
Source of text
DAR 90: 79–84
Physical description
8pp, encl 2pp ALS 4pp

Please cite as

Darwin Correspondence Project, “Letter no. 9259,” accessed on 22 August 2019,

Also published in The Correspondence of Charles Darwin, vol. 22