Popular Science Monthly/Volume 31/July 1887/Human Brain-Weights
ALTHOUGH we may regard it as fully admitted that the external appearance of the skull is no certain indication of the mental caliber of the individual, still there are many who are inclined to measure mind in terms of matter, believing it to be somehow dependent on the material constitution of the brain. Texture, the relative proportions of white and gray matter, and especially weight, are regarded as important factors in the problem, and it is on this latter subject that I have compiled and would offer what, so far as I have been able to ascertain, are trustworthy data concerning the weight of this important organ. The average brain-weight appears to be higher in cold than in warm climates. The "Lancet" has recorded the observation that men with large heads endure cold better than those with small ones. The Lapps have the largest heads in Europe in proportion to their stature; Norwegians next; then come Swedes, Danes, Germans, French and Italians. The Arab head is smaller than any of these. In the Pacific Ocean, far to the north, a people called Chugatshes, with remarkably large heads, occupy the shores and islands of Prince William Sound.
The average size of brain differs also at different stages of life; so that two men, each examining several hundred brains in the same city, may not obtain exactly the same results; because the subjects of the one may be chiefly aged, and those of the other young, though mature. In this case the latter would show a much greater average weight than the former, because of the natural decrease of the brain with advancing years. The following acknowledged authorities have presented the facts as they found them, after weighing a large number of brains:
Dr. John Reid, of the Royal Infirmary, Edinburgh, states the average weight of the encephalon at the age of from five to seven to be forty-three ounces, ten drachms; from twenty to thirty, fifty ounces, nine and a half drachms. The female brain in the human species is generally lighter in mature years than the male by five ounces, or ten per cent, while her stature is only eight per cent less.
Dr. Peacock gives an average of one hundred and thirty-one male brains, between twenty-five and fifty-five years of age, as fifty ounces, three drachms. Dr. Austin Flint, of New York, estimates the male encephalon at 50·2 ounces. Dr. Thurman considers the average brain-weight of ordinary Europeans to be forty-nine ounces. This average may answer for Europe in general, but it would be too small for the colder regions, as shown by the averages of Dr. Reid and Dr. Peacock, taken in Edinburgh, as also it would be too little for New York, according to Dr. Flint.
In Italy, Greece, and Spain, the average is smaller than Dr. Thurman's, and in France, M. Bourgery finds the average weight of the male adult brain to be 46·6 ounces.
The average male brain-weights of different nations is given at—
50·3 oz. from 105 English and Scotch. (Peacock).
49·1 oz. from 18 Germans. (Wagner.)
48·7 oz. from 40 Germans. (Huschke.)
47·3 oz. from 60 Austrians. (Wiesbach.)
47·0 oz. from 28 French. (Parchappe.)
45·4 oz. from 8 African negroes. (Broca.)
43·6 oz. from 7 African negroes. (Various authors.)
We borrow the above table from Dr. Paul Topinard's "Anthropology," 1878, page 311.
To this we add the following average brain-weights, taken from the "Anthropological Review" of 1869, pages 190–192. If we compare the average weight of the African negro brains given in the above table with those of the full-blood negro brains taken from the one hundred and thirty-nine negroes raised in the United States of North America given below, it will be seen that the colder climate of the United States produces heavier brains in the negro than the warm climate of Africa:
139 negro brains in United States averaged
|46·9 oz. avoirdupois.|
1 Guinea negro
|44·4 oz. "|
Hindoos' mean brain-weight
|44·2 oz. "|
3 Ashantees averaged
|42·9 oz. "|
|41·6 oz. "|
2 Congo negroes averaged
|39·7 oz. "|
Dr. A. Wiesbach, a famous investigator of brains in the Austrian Empire, states that the heaviest are found among the Czechs; those of the Roumani are somewhat lighter; the Magyars or Hungarians lighter still; yet their brains average eight grammes more than the Germans of this empire; while the Italians are the smallest of all, being about 25·21 grammes less than the Roumani. The South Slavonian brains are somewhat heavier than the Italian, but lighter than any of the other peoples. One third of the Austrian Empire is peopled by Germans, descended from the natives of Austria proper. The Magyars are Asiatics of the Mongolian race. The South Slavonians occupy the most southern part of the empire, along the low-lying lands of the Danube, which accounts for the small size of their brains; while the Italians are descended from the inhabitants of a still warmer region; all which goes to confirm the theory we have already announced, that the smallest brains belong to the warmest climates. "On comparing the peoples of the four families represented here," continues Dr. Wiesbach, "we find that the Slavonic family possess the largest encephalon, the Romanic the smallest; and that the intermediate Magyars possess a more weighty encephalon than the Germans, which are nearly equal to the Romanic stock."
In a recently-published work Professor Bischoff, an eminent anatomist at Munich, gives the average brain-weight of males as forty-eight ounces ("Nature," January 20, 1881) after weighing five hundred and fifty-nine subjects, the obvious reason for the discrepancy between him and the authors above mentioned being the fact that Munich, situated in the southern part of Germany, is warmer than either Edinburgh or New York.
Dr. Tiedemann, of Heidelberg, on the Alpine plateau of the Rhine in Germany, where it is far colder than Edinburgh in winter, gave the average male brain-weight, for the whole of life above puberty, as 53·25 ounces. Sir W. Hamilton, of Edinburgh, estimated the average adult brain, without distinction of health or disease, at 48·25 ounces, for the whole of life. In London, Dr. Sims found it 46·25 ounces. Luschka gives 50·2 ounces as the average weight of a man's brain; Krause makes it 55·4 ounces, according to an article in the "Morning Herald," Sydney, Australia.
The above averages differ, from several causes. Dr. Tiedemann's observations were limited to fifty-two subjects, and included both sexes, but excluded negroes and very aged persons. Sir W. Hamilton had sixty or seventy of both sexes; Dr. Sims, two hundred and twenty; and Dr. Clendinning still more than Dr. Sims, whose patients were largely among the aged, and those afflicted with long-standing disease. Dr. Clendinning, in the Croonian Lectures, gives the following brain-weights from male subjects, which show that the male encephalon loses more than an ounce every ten years after it is fully grown:
|15 to 30||years||50·75||oz.|
|30 to 50||"||49·66||oz.|
|50 to 70||"||47·1||oz.|
|70 to 100||"||41·5||oz.|
Several other eminent anatomists have made similar exhibits—brain-weight decreasing as the intellectual power increases. It is logical, therefore, to conclude that no parallel exists between power of mind and weight of brain.
M. Nikiforoff, a Russian scientist, in an article in the "Novosti," on the weight of brains, expresses his conviction that the weight of the encephalon has no influence whatever on the mental faculties. But, indeed, any reflecting person who has studied the brain-weights of eminent men as compared with ordinary intelligences must arrive at the same conclusion—that a great mind may belong to a person who carries a very small, a medium-sized, or a very large brain, the size and weight neither adding to the mental power nor detracting from it, provided only that the encephalon is sufficient to give due support to the bodily life. And this leads us to note the relation of the size of the brain to the size of the body of which it forms a part.
The following table is taken from the second volume of the "Science and Practice of Medicine" (London, 1868). Its object is to show the weight of the brain relatively to the weight and height of the body at various ages and in both sexes:
|AGE.||Sex.||Weight of body.||Height of body.||Weight of brain.|
The above table, made by Dr. Boyd from sixteen hundred and seven post-mortem examinations of sane persons, shows that the human brain reaches its maximum of weight in proportion to the rest of the body between the ages of fourteen and twenty in both sexes; and then it continues to decrease through life. While intelligence is rapidly increasing from twenty to sixty years of age, the brain is diminishing. The time that a man knows most is from seventy to eighty; but then his brain is smaller than when he was a boy between seven and fourteen, the age when he thought he knew the most.
Dr. Paul Broca gave the following table of average brain-weights:
|From||1 to 10 years,||985·15||grammes||(34·7 oz.).|
|From||11 to 20 years,||1,465·27||"||(51·68 oz.).|
|From||21 to 30 years,||1,341·53||"||(47·67 oz.).|
|From||31 to 40 years,||1,410·36||"||(49·74 oz.).|
|From||41 to 50 years,||1,391·41||"||(49·07 oz.).|
|From||51 to 60 years,||1,341·19||"||(47·30 oz.).|
|61 and upward,||1,326·21||"||(46·77 oz.).|
By looking over Dr. Boyd's table it will be seen that heavy brains generally belong to tall men; and so, by our table of individuals, it appears that the heaviest is that of Turgeneff, who was a man of large size, while the lighter brains accompanied men of medium or short stature. Women are generally shorter than men, and their brains relatively smaller. Quatrefages says: "We have known for several years that the stature has an influence upon the weight of the brain. It can not be without influence upon the cavity by which the latter is inclosed. Under similar circumstances in other respects, the weight of the brain varies proportionately, or almost proportionately, to the height."
If we accept the above statement that the largest healthy brains are found in the tallest persons, and add to it the phrenological rule that brain-size is a true measure of mental power, it will follow that giants have the greatest minds in the world, which is contradicted by every day's experience. Dr. Ireland, in his work on idiocy and imbecility, mentions two cretins, each six feet high; several idiot Calibans, six feet six inches; several idiots described by Lomboso, one of whom was eight and a half feet, another seven feet eight inches, with a sister the same height. Large stature may be a general indication of large brain-weight, but the latter can not be taken as a safe index of high intellectual power.