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.
But it is of more importance for our present inquiry to note that, as exceptionally large and heavy brains occur among the most civilised races, in some cases—and in some only—accompanied with corresponding manifestations of unusual intellectual power; so also it becomes apparent that skulls much exceeding the average, and some of remarkable internal capacity, are met with among barbarian races, and even among some of the lowest savages. Taking the crania in the elaborate series of tables in Dr. J. B. Davis’s Thesaurus Craniorum, with an internal capacity above 100 cubic inches, they will rank in order as follows:—
| Chinese | 111.8 |
| Maduran | 110.6 |
| Marquesan | 110.6 |
| Kanaka | 108.8 |
| Javan | 107. |
| Negro | 105.8 |
| Australian | 104.5 |
| Kafir | 104.5 |
| Bakele | 103.3 |
| Tidorese | 103.3 |
| Bhotia | 102.7 |
| Bodo | 100.9 |
| Hindoo | 100.9 |
| Sumatra | 100.9 |
Among the European series the largest is an Irish cranium of 121.6 cubic inches, and next to it comes an Italian, 114.3, and an Englishman, 112.4; an ancient Briton from a Yorkshire Long Barrow, 109.4; an ancient Roman, 106.4; a Lapp, 105.8; an ancient Gaul, 103.7; a Briton of Roman times, 103.3; a Merovingian Frank, 101.5; and an Anglo-Saxon, 100.9. Those and other examples of the like kind are full of interest as showing the recurrence of megalocephalic variations from the common cranial and cerebral standard among ancient races; and among rudest savages as well as among the most cultivated classes of modern civilised nations. But the order shown in the above instances is derived from purely exceptional examples, and is no key to the relative capacity of the races named.
Opportunities for testing the size and weight of the brain among barbarous races are only rarely accessible to those who are qualified to avail themselves of them for the purposes of science. Some near approximation to the relative brain-weight of the English, Scotch, German, and French, may now be assumed to have been established. Dr. Thurnam instituted a comparison between those and two of the prehistoric races of Britain—the Dolichocephali of the Long Barrows, and the Brachycephali of the Round Barrows of England.[[176]] The results are curious, as showing not only a greater capacity in the ancient British skulls than the average modern German, French, or English head; but an actual average higher than that of all but five of the most distinguished men of Europe, whose brain-weights have been recorded. On comparing the ancient skulls with those of modern Europeans, as determined by gauging the capacity of both by the same process, the following are the results presented, according to the authorities named:—