By GEORGE J. ROMANES.
IN his "Descent of Man" Mr. Darwin has shown at length that what Hunter termed secondary sexual characters occur throughout the whole animal series, at least as far down in the zoölogical scale as the Articulata. The secondary sexual characters with which he is chiefly concerned are of a bodily kind, such as plumage of birds, horns of mammals, etc. But I think it is evident that secondary sexual characters of a mental kind are of no less general occurrence. Moreover, if we take a broad view of these psychological differences, it becomes instructively apparent that a general uniformity pervades them—that while within the limits of each species the male differs psychologically from the female, in the animal kingdom as a whole the males admit of being classified, as it were, in one psychological species and the females in another. By this, of course, I do not mean that there is usually a greater psychological difference between the two sexes of the same species than there is between the same sexes of different species: I mean only that the points wherein the two sexes differ psychologically are more or less similar wherever these differences occur.
It is probably due to a recognition of this fact that from the very earliest stages of culture mankind has been accustomed to read into all nature—inanimate as well as animate—differences of the same kind. Whether it be in the person of Maya, of the pagan goddesses, of the Virgin Mary, or in the personifications of sundry natural objects and processes, we uniformly encounter the conception of a feminine principle coexisting with a masculine in the general frame of the cosmos. And this fact, as I have said, is presumably due to a recognition by mankind of the uniformity as well as the generality of psychological distinction as determined by sex.
I will now briefly enumerate what appeared to me the leading features of this distinction in the case of mankind, adopting the ordinary classification of mental faculties as those of intellect, emotion, and will.
Seeing that the average brain-weight of women is about five ounces less than that of men, on merely anatomical grounds we should be prepared to expect a marked inferiority of intellectual power in the former. Moreover, as the general physique of women is less robust
- This is proportionally a greater difference than that between the male and female organisms as a whole, and the amount of it is largely affected by grade of civilization—being least in savages and most in ourselves. Moreover, Sir J. Crichton Browne informs me, as a result of many observations which he is now making upon the subject, that not only is the gray matter, or cortex, of the female brain shallower than that of the male, but also receives less than a proportional supply of blood. For these reasons, and also because the differences in question date from an embryonic period of life, he concludes that they constitute "a fundamental sexual distinction, and not one that can be explained on the hypothesis that the educational advantages enjoyed cither by the individual man or by the male sex generally through a long series of generations have stimulated the growth of the brain in the one sex more than in the other."