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Darwin Correspondence Project

From Henry Gillman   31 October 1871

80 Elizabeth Street West, | Detroit, Michigan,

October 31st. 1871.

Chas. Darwin Esqr.

Down, Beckenham, Kent, Engd.,

My Dear Sir,

In my last letter to you I had intended but neglected to give you some interesting facts which came to my knowledge about two years ago in regard to the race known as the “ancient mound-builders” of this continent.1 In 1869 I obtained from the mounds on the Detroit and the Rouge Rivers a large amount of the relics of this race of great interest. Among them were their bones, which presented many peculiarities; the tibiae being remarkably flat; in this respect resembling the bones from the Caves of France and of Gibraltar.2 A quantity of those relics were presented by me to the American Museum of Archæology & Ethnology; and the attention of the Curator, Prof. Wyman,3 was at once attracted by the conformation of the tibiae, which he pronounced the first instance of the facts being known in regard to the northern race, though bones from the mounds in Florida had shown the characteristics had belonged to the Southern mound-builders. In the 4th. Annual report of the museum, pp. 21, 22, one of the tibiae found by me on the River Rouge, Michigan, is specially referred to, as the most extreme case of the flattening of this bone, the transverse being only 0.48 of the fore and aft diameter.4 Tibiae from other parts of the country showed the extent of flattening as 0.60; and in “the most marked case mentioned by Broca—viz: the old man from Cro-Magnon (France) it was 0.60”.5 But I have since met with many cases presenting this flatness in even a greater extreme, & I have in my collection two tibiae, taken by me from a mound on the Detroit River, in one of which the short is 0.42 of the long diameter, and in the other only 0.40. This last, therefore may be considered the flattest tibia on record. Interesting relics of the ancient race were associated with those bones, which were selected from among the remains of eleven human bodies. Some of these relics gave evidence of the identity of this race with the “ancient miners” of Lake Superior, or, at least established their intercourse; others evidently point to transactions with the Southern races—perhaps along the Gulf of Mexico. In all of the mounds along the Detroit River & its tributary the River Rouge, I find a large majority of the tibiae present this flattening. This appears an exception to the facts as noted in other parts of our country, where the flattening has been estimated as pertaining to “only about one third of all the individuals observed”. Here a tibia not flattened forms the exception. I would further state that where this bone is found approximating to the equilateral, it is manifestly of subsequent burial and of much later date. Prof. Wyman gives interesting comparisons of the mound-builders with the ancient races of Europe, in which the flattening of the tibia was one of the peculiarities. He also calls attention to the same characteristic in the corresponding bones of the ape. He says—“In some of the tibiae the amount of flattening surpasses that of the gorilla and chimpanzee, in each of which we found the short 0.67 of the long diameter, while in the tibia from Michigan it was only 0.48”. But as above shown, I have found even more extreme cases since.

I have been disappointed in not seeing your sons in Detroit as I expected from your letter.6 Have they changed their intention? I have been lately absent from home very much—that is since the month of August, and have visited Lakes Superior, Michigan, St. Clair, Huron and Erie this Summer and Autumn. I am at present looking forward to a little rest at home—

I have lately found time to read your “Descent of Man”, and like it very much, considering it quite moderate, in view of the outcry raised by some. Still “Progressive development” is progressing; and if all do not take your view of the manner in which the great results are produced, it is hardly to be wondered at. Every day is opening to our view some new fact, strengthening old positions or casting light on new ones.—

Did Space & time permit, it would have given me pleasure to add some facts which have lately come to my observation.— During the past season I have added to my collection of facts in the interesting field of the Variation of plants in a natural or uncultivated condition.— It requires much patient thought and judgement to systematize these and establish, or rather arrive at the laws governing them.— In addition to the variations of the Common Dandelion already mentioned in a former letter,7 I have found it this Season, which has been a remarkably dry one, with a perfect bract-like leaf on the scape, variously situated, from the middle, to nearer either extremity; but generally about 13 of the distance or about two or three inches below the Calyx.

In 1870 I found in my garden two instances of the Morning Glory, seedlings, with three instead of the usual two cotyledonous leaves. I watched the plants through the season to trace further variation; but none was perceived till the production of the flowers, in which I found the corolla with a cleft in it, having the appearance of a piece cut out, the sepal on the same side being enlarged, & more or less in both texture & color resembling the corolla. In some cases the piece wanting in the corolla seemed adherent to the sepal. I preserved the seed from these, and this year produced from it plants, in which, though I did not observe the three Cotyledonous leaves, all the other peculiarities mentioned were even more abundant & even intensified; the stamens frequently participating, being adherent their entire length to the cleft or notched part—that is a single stamen running into this cleft. I have this season (1871) carefully preserved the seed from flowers presenting this singular variation, & shall try whether a further development may not be produced next season. Would you like some of the seed?— I can let you have it.

Some of the facts given in this letter—relating to the “mound-builders”—I have sent to the “American Naturalist”, & they appear with some others from me in the October number. Do you ever see this monthly? Trübner & Co. are the London agents. I will try & procure this number to send you.—8

With best wishes | Very Sincerely Yours | Henry Gillman.


Gillman published on the mound-builders in the Annual Report of the Smithsonian Institution (Gillman 1873). On prehistoric platycnemism, see also letter from W. B. Dawkins, 8 February 1871 and n. 2.
Jeffries Wyman was curator of the Peabody Museum of American Archaeology and Ethnology at Harvard University.
Gillman refers to Wyman 1871, in the Reports of the Peabody Museum of American Archaeology and Ethnology.
Gillman refers to Paul Broca and Broca 1868, pp. 365–70.
George Howard and Francis Darwin had been touring the United States (see letter to Asa Gray, 16 July [1871]). CD’s letter to Gillman has not been found.
Gillman’s note, ‘The flattest tibia on record’, appeared in American Naturalist 5 (1871): 663–4. There is a series of American Naturalist, from March 1871 until 1882, in CD’s unbound journal collection in the Darwin Archive–CUL.


Broca, Paul. 1868. Sur les crânes et les ossements des Eyzies. [Read 21 May 1868.] Bulletins de la Société d’Anthopologie de Paris 2d ser. 3: 350–91.

Gillman, Henry. 1873. The mound-builders and platycnemism in Michigan. Annual Report of the Board of Regents of the Smithsonian Institution (1873): 364–90.

Wyman, Jeffries. 1871. Observations on crania and other parts of the skeleton. Reports of the Peabody Museum of American Archæology and Ethnology in Connection with Harvard University 1 (1868–76), Fourth Annual Report (1871), pp. 10–24.


Sends details of his discoveries of relics and bones of the "mound-builders", and Jeffries Wyman’s comments on them.

Letter details

Letter no.
Henry Gillman
Charles Robert Darwin
Sent from
Source of text
DAR 165: 48
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 8038,” accessed on 16 November 2019,

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