Woman in Science / With an Introductory Chapter on Woman's Long Struggle for Things of the Mind

by J. A. Zahm

But much stress as has been laid on physical power, health and cranial capacity, as determining factors of intellectual capacity and sexual differences, far greater stress has been laid on conclusions deducible from the relative brain weights of different classes of people as well as of different sexes. It was assumed that by a critical study of the brain, by careful weighings of many brains of both sexes and of many races, it would be easy to secure conclusive evidence that the size and weight of the brain increase with the amount of intelligence of the individual. It was also assumed that function not only makes the organ, but also develops it. Brain became synonymous with mind. A large brain implied vigor of thought; a small brain was evidence of mental inferiority.

Physiology had demonstrated unquestionably that the muscles of the body are enlarged by exercise. It was assumed by those who are wont to measure mind in terms of matter that the brain, being the organ of thought, was also developed by exercise. It was also assumed that the development of the brain was in a direct ratio to its activity. The greater its activity the greater its mass, and the greater the mass the greater the degree of intelligence. In other words, it was assumed that there was an exact and invariable proportion between weight of brain and amount of brain power.

None of the theories which have already been adverted to have been so full of assumptions and prejudices or vitiated by so many fallacies and over-hasty generalizations as this. No subject has possessed a greater fascination for anthropologists, and no subject has been prolific in more diverse and conflicting conclusions. Many men of science who, in other matters, were noted for their care in weighing evidence, before formulating theories, completely lost the scientific spirit when they began to weigh brains and to draw conclusions respecting the relations of brain weight and mental power, and to establish ratios between the character of the convolutions of the organ of thought and the degree of intelligence of its possessor.

Contrary to what is generally believed, a large brain is not always an indication of superior capacity or intelligence. There have been, it is true, a number of men of genius who were the possessors of large brains, but there have also been others whose brains were of but medium weight.

The largest known brains of intellectual workers were those of Cuvier, the noted zoölogist, and Turgenieff, the distinguished novelist. The brain of the Frenchman weighed 1830 grams, while that of the Russian totaled 2012 grams. Among other large brains—even larger than Cuvier's—were those of a bricklayer, which weighed 1900 grams, and of an ordinary laborer, which reached 1924 grams. The largest brains on record were that of an ignorant laborer named Rustan, which weighed 2222 grams; that of a weak-minded London newsboy, which weighed 2268 grams, and that of a twenty-one-year-old epileptic idiot, which had the unheard of weight of 2850 grams.[96]

The seven largest recorded female brains were three weighing 1580 grams each, one of which belonged to a medical student of marked ability, while the other two belonged to quite undistinguished women. There were two others weighing 1587 each, one of which belonged to an insane woman. Still heavier than these by far were the brains of an insane woman who died of consumption, and of a dwarfed Indian squaw. The brain of the first weighed 1742 grams; while that of the second was no less than 2084 grams.

From the foregoing examples it is evident that a large brain is far from being a certain index of mental capacity or of superior intelligence. It is frequently the very reverse. If, for instance, it fail to receive the necessary supply of blood, it will be inert or disordered and will prove to be a dangerous possession rather than a precious endowment. Epileptics usually have brains that are large relatively to the size of the body. And, while it is probably true that the great thinkers and men of action of the world have, in most instances, had comparatively large brains, it is also true that the brain weights of but few of them exceeded 1500 grams, while those of many fall below 1200 grams.

Thus the brain of Gambetta, "the foremost Frenchman of his time," weighed only 1159 grams, while the weight of the brain of Napoleon I was 1502 grams—barely equal to that of a negro described by the anthropologist Broca, and but little superior to that of a Hottentot mentioned by Dr. Jeffries Wyman.[97]

The late Dr. Joseph Simms found the average brain weight of sixty persons who were either imbeciles, idiots, criminals or men of ordinary mind to be 1792 grams, while that of sixty famous men was 1454 grams, a difference in favor of men not noted for intellectual greatness of 338 grams. These figures are far from showing that large brains are a necessary concomitant of mental capacity.

In view of these and many similar facts, we are not surprised that the eminent German anatomist and anthropologist, Rudolph Wagner, should declare that "very intelligent men do not differ strikingly in brain weight from less gifted men," and that the noted French physician, Esquirol, should assert that "no size or form of head or brain is incident to idiocy or superior talent."