Part 39

On the general question of cranial development as an index of cerebral capacity, Professor Welcker assigns a standard, which was accepted by Dr. Thurnam, thus: “Skulls of more than 540 to 550 millimetres in horizontal circumference (the weight of brain belonging to which is 1490 to 1560 grms., or 52.5-55 oz. av.), are to be regarded as exceptionally large. The designation of _kephalones_, proposed by Virchow, might commence from this point. Men with great mental endowments fall, for the most part, under the definition of kephalony. If we consider the relations of capacity, 1800 grms. (63.5 oz.) appears to be the greatest attainable weight of brain within a skull not pathologically enlarged.” But the brain of Cuvier—the heaviest healthy brain yet recorded,—exceeded this. Its weight is stated by Wagner as 1861 grms., or 65.8 oz.; but this M. Broca corrects to 1829.96 grms. Even thus reduced it exceeds the limits assigned by Professor Welcker to the normal healthy brain. But a curious commentary upon this is furnished by the fact that the modern English skull which Dr. Davis selects as presenting the most striking analogy to the Neanderthal skull—“the most ape-like skull which Professor Huxley had ever beheld,”—though marked not only by the prominence of the superciliary ridges, but by great depression of the frontal region, appears to have a cubical capacity equivalent to that of Dr. Abercrombie, whose brain is only surpassed by that of Cuvier among the ascertained brain-weights of distinguished men.[174] Its capacity is 94 oz. of sand, or 113 cubic inches, equivalent—after making the requisite deduction for membranes and fluids,—to a brain-weight of 63 oz.

I have attempted in the following table to reduce to some common standard such imperfect glimpses as are recoverable of the cranial capacity of some distinguished men, of whose actual brain-weights no record exists:—

TABLE III

CRANIAL CAPACITY OF DISTINGUISHED MEN

────────────────────┬────────┬──────────┬───────────────┬─────────────── │ │ │ │ │Length. │ Breadth. │Circumference. │ Estimated │ │ │ │ Brain-Weight. │ │ │ │ ────────────────────┼────────┼──────────┼───────────────┼─────────────── │ │ │ │ Dante │ — │ — │ — │ 51.3 Robert the Bruce │ 7.70 │ 6.25 │ 22.25 │ — Burns │ 8.00 │ 5.95 │ 22.25 │ — Scott (head) │ 9.00 │ 6.40 │ 23.10 │ — Heinse │ — │ 5.30 │ — │ 48.0 Bünger │ — │ 5.00 │ — │ 49.8 Ugo Foscolo │ 6.90 │ 5.70 │ 20.50 │ 48.4 │ │ │ │ ────────────────────┴────────┴──────────┴───────────────┴───────────────

Some of the examples adduced in the above table appear to exhibit instances of mental endowment of high character, without the corresponding degree of cranial, and consequently cerebral development. The following table exhibits recorded examples of a series of actual brain-weights of distinguished men. It seems to lend confirmation to the idea that great manifestation of mental endowment is correlated, in the majority of observed cases, to a brain above the normal average in mass or weight. But even here intellect and brain-weight are not strictly in uniform ratio. Several of the following brain-weights, including that of Tiedemann, are furnished by Wagner, in the _Vorstudien des Menschlichen Gehirns_; but in an elaborate table of brain-weights given in the _Morphologie und physiologie des Menschlichen gehirns als Seelenorgan_, the brain of Byron is classed above all except Cuvier; while Vogt gives the same place, by estimate, to Schiller’s, as next in rank to that of the great naturalist among highly developed brains. Dr. Thurnam states his authorities for others, when producing them in his valuable contribution to the _Journal of Mental Science_ “On the Weight of the Brain.” For that of Webster he refers to “the unsatisfactory article on the brain of Daniel Webster, _Edin. Med. Surg. Journ._, vol. lxxix. p. 355.” Dr. J. C. Nott, in his “Comparative Anatomy of Races” (_Types of Mankind_, p. 453), says: “Dr. Wyman, in his _post-mortem_ examination of the famed Daniel Webster, found the internal capacity of the cranium to be 122 cubic inches, and in a private letter to me, he says: ‘The circumference was measured outside of the integuments before the scalp was removed, and may, perhaps, as there was much emaciation, be a little less than in health.’ It was 23¾ inches in circumference; and the Doctor states that it is well known there are several heads in Boston larger than Webster’s. I have myself, in the last few weeks, measured half a dozen heads as large and larger.” The circumference, it will be seen, exceeds the corresponding measurement of Scott’s head, taken under similar circumstances. But the statement of 122 cubic inches as the internal capacity of Webster’s skull seems open to question. If correct, instead of 53.5 oz. of brain-weight as stated in the following table, it is the equivalent of a brain-weight of fully 65 oz., or one in excess even of that, of Cuvier. The brain-weights of Goodsir, Simpson, and Agassiz, are given in the following table from the reported autopsy in each case:—

TABLE IV

BRAIN-WEIGHTS OF DISTINGUISHED MEN

─────┬────────────────────┬─────────────────────────┬──────┬──────┬────── │ │ │ │ │ │ │ │ Age. │Oz. │Grms. │ │ │ │ │ ─────┼────────────────────┼─────────────────────────┼──────┼──────┼────── │ │ │ │ │ 1│Cuvier │Naturalist │ 63 │64.5 │ 1830 2│Byron │Poet │ 36 │63.5? │ 1799 3│Abercrombie │Philosopher, Physician │ 64 │63. │ 1785 4│Schiller │Poet │ 46 │63.? │ 1785 5│Goodsir │Anatomist │ 53 │57.55 │ 1629 6│George Brown │Statesman (Canadian) │ 61 │56.3 │ 1595 7│Harrison │Chief Justice │ 45 │56. │ 1586 8│Spurzheim │Phrenologist, Physician │ 56 │55.06 │ 1575 9│Simpson │Physician, Archæologist │ 59 │54. │ 1530 10│Dirichlet │Mathematician │ 54 │53.6 │ 1520 11│De Morny │Statesman │ 50 │53.6 │ 1520 12│Napoleon I. │General, Statesman │ 52 │53.5 │ 1516 13│Daniel Webster │Statesman │ 70 │53.5 │ 1516 14│Campbell │Lord Chancellor │ 80 │53.5 │ 1516 15│Agassiz │Naturalist │ 66 │53.4 │ 1512 16│Chalmers │Author, Preacher │ 67 │53. │ 1502 17│Fuchs │Pathologist │ 52 │52.9 │ 1499 18│De Morgan │Mathematician │ 73 │52.7 │ 1493 19│Gauss │Mathematician │ 78 │52.6 │ 1492 20│Broca │Anthropologist │ — │52.5 │ 1488 21│Dupuytren │Surgeon │ 58 │50.7 │ 1436 22│Grote │Historian │ 76 │49.75 │ 1410 23│Whewell │Philosopher │ 71 │49. │ 1390 24│Hermann │Philologist │ 51 │47.9 │ 1358 25│Tiedemann │Physiologist │ 80 │44.2 │ 1254 26│Hausmann │Mineralogist │ 77 │43.2 │ 1226 │ │ │ │ │ ─────┴────────────────────┴─────────────────────────┴──────┴──────┴──────

Dr. Thurnam, in producing fifteen of the above examples, remarks: “Altogether, they decidedly confirm the generally received view of the connection between size of brain and mental power and intelligence”; and he adds his conviction that if the examination of the brain in the upper ranks of society, and in men whose mental endowments are well known, were more generally available, further confirmation would be given to this conclusion. The converse, at least, is certain, that no great intelligence or unwonted mental power is possible with a brain much below the average in mass and weight But while the above list exhibits a series of exceptionally high brain-weights of distinguished men, the relative weights in some cases—as in Napoleon—are calculated to excite surprise if viewed as an index of comparative intellectual capacity. On the other hand, those lowest in the scale, and below the mean weight, include men of undoubted eminence in letters and science; while the proofs are no less unquestionable that a large healthy brain is not invariably the organ of unwonted intelligence or mental activity.

In the _Philosophical Transactions_ of 1861, Dr. Boyd published an elaborate series of researches illustrative of the weight of various organs of the human body, including the weights of two thousand brains. Most of the healthy brains are those of patients in the St. Marylebone Infirmary, and have already been referred to as necessarily representing the indigent and uneducated classes of London. Here, therefore, if an unusually large brain is the index of intellectual power, every probability was against the occurrence of brains above the average size or weight. But the results by no means confirm this assumption. Among the patients in the Edinburgh Royal Infirmary, in like manner, though including the better class of artizans and others from country districts, we might still look for a confirmation of M. Broca’s assumption, based on extensive observations of French crania, “that, other things being equal, whether as the result of education, or by hereditary transmission, the volume of the skull, and consequently of the brain, is greater in the higher than in the lower classes.” But Dr. Peacock’s tables include four brain-weights, three of them of a sailor, a printer, and a tailor, respectively, ranging from 61 to 62.75 oz.; and so surpassing all but two, or at the most three, of the heaviest ascertained brain-weights of distinguished men. Tried by the posthumous test of internal capacity, three skulls of nameless Frenchmen, derived from the common cemeteries of Paris, in like manner showed brains equalling in size that of Cuvier. The following are the maximum brain-weights among the St. Marylebone patients apparently unaffected by cerebral disease:—

TABLE V

MAXIMUM BRAIN-WEIGHTS—ST. MARYLEBONE

───────────────┰─────────────────────┰───────────────────── ┃ ┃ AGE. ┃ MALE. ┃ FEMALE. ┃ Oz. Grms. ┃ Oz. Grms. ┃ ┃ ───────────────╂─────────────────────╂───────────────────── ┃ ┃ 7-14 ┃ 57.25 1622 ┃ 52.00 1473 14-20 ┃ 58.50 1658 ┃ 52.00 1473 20-30 ┃ 57.00 1615 ┃ 55.25 1565 30-40 ┃ 60.75 1721 ┃ 53.00 1502 40-50 ┃ 60.00 1700 ┃ 52.50 1488 50-60 ┃ 59.00 1672 ┃ 52.50 1488 60-70 ┃ 59.50 1686 ┃ 54.00 1530 70-80 ┃ 55.25 1565 ┃ 49.50 1403 80 ┃ 53.75 1523 ┃ 48.00 1360 All Ages. ┃ ┃ 7-80 ┃ 60.75 1721 ┃ 55.25 1565 ┃ ┃ ───────────────┸─────────────────────┸─────────────────────

The stature, or relative size of body, has already been referred to as an element in testing the comparative male and female weight of brain; and it is one which ought not to be overlooked in estimating the comparative size and weight of the brains of distinguished men. From my own recollections of Dr. Chalmers, who was of moderate stature, his head appeared proportionally large. The same was noticeable in the cases of Lord Jeffrey, Lord Macaulay, Sir James Y. Simpson, and very markedly so in that of De Quincey. The philosopher Kant was also of small stature; and Dr. Thurnam refers to the observation of Carus that he had a head not absolutely large, though, in proportion to the small and puny body of that eminent thinker, it was of remarkable size. Among the large-brained artizans of the Marylebone Infirmary, on the contrary, the probabilities are in favour of a majority of them being men of full muscular development and ample stature. Nevertheless, with every allowance for this, it still remains probable, if not demonstrable, that from the same humble and unnoted class, examples of megalocephaly could be selected little short in cerebral mass, and apparently in brain-weight, of the group of men whose large brains are recognised as the concomitants of exceptionally great mental capacity and intellectual vigour. Unless, therefore, we are contented to accept the poet’s dictum, “Their lot forbad,”[175] and assume that “chill penury repressed their noble rage, and froze the genial current of the soul,” it is manifest that other elements besides those of volume or weight are essential as cerebral indices of mental power. Dr. Thurnam, after noting examples that had come under his own notice of brain-weights above the medium—but which, as those of insane patients, may be assigned to other causes than healthy cerebral development,—adds: “The heaviest brain weighed by me (62 oz., or 1760 grms.) was that of an uneducated butcher, who was just able to read, and who died suddenly of epilepsy, combined with mania, after about a year’s illness. The head was large, but well-formed; the brain of normal consistence; the _puncta vasculosa_ numerous.” In cases like this, of weighty brain with no corresponding manifestation of intellectual power, something else was wanting besides an ampler sphere. The mere position of a humble artizan or labourer will not suffice to mar the capacity to “make by force his merit known,” which pertains to the “divinely gifted man.”

Arkwright, Franklin, Watt, Stephenson, Farraday, Hugh Miller, and others of the like type of self-made men, are not rare. Among the large-brained artizans, scarcely one can have had a more limited sphere for the exercise of mental vigour than the poet Burns, the child of poverty and toil, who refers to his own early years as passed in “the unceasing moil of a galley-slave.” In his case the very means essential to a healthy physical development were stinted at the most critical period of life. His brother Gilbert says: “We lived sparingly. For several years butcher’s meat was a stranger to the house; while all exerted themselves to the utmost of their strength, and rather beyond it, in the labours of the farm. My brother, at the age of thirteen, assisted in thrashing the crop of corn, and at fifteen was the principal labourer on the farm.” Such premature toil and privations left their permanent stamp on his frame. “Externally, the consequences appeared in a stoop of the shoulders, which never left him; but internally, in the more serious form of mental depression, attended by a nervous disorder which affected the movements of the heart.” He had only exchanged the toil on his father’s farm for equally unremitting labour on his own, when the finest of his poems were written; nor would it be inconsistent with all the facts to assume that the privations of his early life diminished his capacity for continuous mental activity; as it undoubtedly impaired his physical constitution. But, while the possession of a brain much above the average in size might have seemed to account for his triumph over the depressing influences of his limited sphere, the fact that his brain appears to have been below the average size, points to some other requisite than mere cerebral mass as essential to intellectual vigour.

The brain is influenced in all its functions by the character and the amount of blood circulating through it, and promptly manifests the effects of any deleterious substance, such as alcohol or opium, introduced into its tissues. It depends, like other portions of the nervous system, on an adequate supply of nourishment. In both respects the brain of the Ayrshire poet was injuriously affected, in so far as we may infer from all the known circumstances of his life.

The human brain is large in proportion to the body in infancy and youth; and the opinions of leading anatomists and physiologists early in the present century favoured the idea that it attained its full size within a few years after birth. Professor Sœmmering assumed this to take place so early as the third year. Sir William Hamilton explicitly stated his conclusion thus: “In man the encephalon reaches its full size about seven years of age”; and Tiedemann assigns the eighth year as that in which it attains its greatest development. But the more accurate and extended observations since carried on rather tend to the conclusion that the brain not only goes on increasing in size and weight to a much later period of life; but that it is healthfully stimulated by habitual activity, and under exceptionally favouring circumstances it may increase in weight long after the body has attained its maximum.

The largest average brain-weights, as determined by observations on the brains of upwards of 2000 men and women in different countries of Europe, have indeed been found in those not above twenty years of age; and from a nearly equal number of English examples, Dr. Boyd determines the period of greatest average weight to be the interval between fourteen and twenty years of age; but this includes cases in which death has ensued from undue or premature brain development.

Other evidence leaves no room for doubt that cases are not rare of the growth, or increased density of the brain up to middle age; while the observations of Professor Welcker indicate this process extended to a later period of life. The average brain-weights, as given by Boyd, Peacock, and Broca, from healthy or sane cases, along with those of Welcker, include the weights of 47 male brains from ten to twenty years of age, giving an average of 49.6 oz., or 1405 grms.; and of 112 male brains from twenty to thirty years of age, giving an average of 48.9 oz., or 1384 grms.; and the results of a nearly equal number of female brains closely approximate. They embrace English, Scotch, German, and French, men and women. Dr. Welcker’s results indicate the period of maximum brain-weight to be between 30-40, as shown in the following table:—

TABLE VI

AVERAGE WEIGHT OF THE BRAIN AT DIFFERENT AGES

───────────────┰─────────────────────┰───────────────────── ┃ ┃ AGE. ┃ MALE. ┃ FEMALE. ┃ Oz. Av. Grms. ┃ Oz. Av. Grms. ┃ ┃ ───────────────╂─────────────────────╂───────────────────── ┃ ┃ From 10-20 ┃ 47.5 1346 ┃ 43.1 1221 20-30 ┃ 49.5 1404 ┃ 44.1 1251 30-40 ┃ 49.5 1404 ┃ 44.8 1272 40-50 ┃ 48.6 1379 ┃ 43.5 1234 50-60 ┃ 48.1 1365 ┃ 43.5 1234 60-70 ┃ 46.1 1306 ┃ 42.8 1213 ┃ ┃ ───────────────┸─────────────────────┸─────────────────────

In the female examples, amounting to thirty-one between seventy and eighty years of age, and six between eighty and ninety, the continuous diminution of brain-weight corresponds with the increasing age; but in the male examples, sixty-five cases between sixty and seventy years of age yield an average brain-weight of 46.1 oz., while twenty-seven cases between seventy and eighty years of age give 47.9 as the average; falling in the next decade to 43.8.

It may be inferred from the number of cases pointing to an early attainment of the highest average brain-weight, not that the brain differs from all other internal organs of the human body in attaining its maximum before the period of puberty; but that physical as well as mental vigour are dependent on the maintenance of a nice equilibrium between the brain and the other organs while in process of development. The observations of Dr. Boyd, including the results of 2614 _post-mortem_ examinations of sane and insane patients of all ages, showed that the average weight of the brain of “still-born” children at the full period was much greater than that of the new-born living child. It is a legitimate inference, therefore, that death in the former cases was traceable to an excessive premature development of the brain. Again, when it is shown from numerous cases that the highest average weights of brain in both sexes occur not later than twenty years of age, it appears a more legitimate inference to trace to exceptional cerebral development towards the period of adolescence, the mortality which rendered available so many examples of unusually large or heavy brains, than to assume that the normal healthy brain begins to diminish at that age.

It is a fact familiar to popular observation that a large head in youth is apt to be unfavourable to life. A tendency to epilepsy appears to be the frequent concomitant of an unusually large brain; and with the congestion accompanying its abnormal condition, this may account for the weights of such diseased brains as have been repeatedly found in excess of nearly all the recorded examples of megalocephaly in the cases of distinguished men. But a greater interest attaches to a remarkable example of healthy megalocephaly recorded in the _British Medical Journal_ for 1872. The case was that of a boy thirteen years of age, who died in Middlesex Hospital from injuries caused by a fall from an omnibus. His brain was found to weigh 58 oz. He had been a particularly healthy lad, without any evidence of rachitis, and very intelligent. This is a strikingly exceptional case of a healthy brain, at the age of thirteen, exceeding in weight all but two of the greatest ascertained brain-weights of distinguished men.

From the evidence already adduced of relative cubical capacity of the skulls of different races, it appears, as was to be expected, that there is a greater prevalence of the amply-developed brain among the higher and more civilised races. But all averages are apt to be deceptive; and the progressive scale from the smallest up to the greatest mass of brain is by no means in the precise ratio of an intellectual scale of progression. The results of Dr. J. B. Davis’s investigations, based on the study of a large, and in many cases a seemingly adequate number of skulls, bring out this remarkable fact, that, so far from the Polynesians occupying a rank in the lowest scale, as affirmed by Professor Vogt, the Oceanic races of the Pacific generally rank in internal capacity of skull, and consequent size of brain, next to the European.