The human species

by A. de Quatrefages

This remark is important. In the question under discussion it will not do to compare separately the celebrities who figure in Wagner’s table; we must connect them with the rest of mankind, with diseased, as well as with other brains. To act otherwise would be to give rise to the idea that we had wished to evade a difficulty by neglecting to turn the attention to the fact that, immediately after the brain of Byron, and long before that of Gauss, stands the brain of a madman. Are, then, genius and madness in such close relationship? Are the volume, the weight, and the peculiar characters of Cuvier’s brain indeed due to a hypertrophy which came to a standstill just at the right moment, as Gratiolet thought?

III. However abridged and curtailed this statement of facts may be, it seems to me sufficient to justify us in drawing conclusions equally applicable to individuals and to races.

We shall certainly not be accused of an exaggerated immaterialism if we estimate the action of the brain as we estimate the action of a muscle. Now experience and observation daily testify that in the latter volume and form are not everything. Functional energy often more than compensates for what is wanting with respect to mass. Many other organic systems would furnish similar facts, well-known to all doctors and all physiologists. To assert that the case is different with the brain would be, even in the absence of all direct observation, a purely gratuitous hypothesis, and, in the presence of Wagner’s tables, a contradiction of evidence. With his small brain, Haussmann, the correspondent of the French Institute, has evidently surpassed, in the matter of intelligence, almost all his large-headed contemporaries.

But, on the other hand, beyond a certain stage of decrease, the muscular apparatus becomes incapable of effort. We can readily understand that it should be so with the brain also. It is, therefore, most natural to find that, when it has fallen below a certain volume and weight, it gradually passes from weakness to impotence. Even M. de Bonald could not consider it strange, that an intelligence when provided only with imperfect or almost useless organs, should only manifest itself in an incomplete manner.

Thus, irrespective of all dogmatic or philosophic ideas, we are led to the conclusion that there is a certain relation between the development of the intelligence and the volume and weight of the brain. But, at the same time, we must allow that the material element, that which is appreciable to our senses, is not the only one which we must take into account, for behind it lies hidden an unknown quantity, an x, at present undetermined and only recognised by its effects.

IV. Thus from this fact alone it follows that we cannot act with too much caution in forming an estimate of a race from the dimensions of its cranium, and the relative development of the bones of which it is composed. Gratiolet proposed to distinguish frontal, parietal, and occipital races, characterised by the predominance of the anterior, medial and posterior regions of the cranium and the brain. If we accept the word character as it is understood by naturalists, we shall have no objection to make to these denominations. But to go beyond that, to attribute to one or other of these races any kind of superiority by virtue of any one or other of these characters, would be mere hypothesis. In fact, the Basques, with their occipital dolichocephaly, are in no way inferior to the frontal dolichocephali of Paris.

V. In those phenomena, amongst which, à priori, we should be tempted to look for ethnological characters, we must give the first place to organic evolution at different periods of life. Now, the examination of facts establishes the important fact, that, in this respect, all human races present a remarkable uniformity. When some slight differences are manifested, they show such coincidence with the action of the conditions of life, that it is impossible not to recognise the relation of cause and effect, and this fact alone produced a most significant intercrossing between peoples evidently identical in origin. Thus, the whole mass of physiological phenomena, considered as characters, add one more proof in favour of the monogenistic theory. A few examples will suffice to justify these statements.

VI. Let us first prove that the duration of gestation is the same in all human races. The importance of this fact will be readily understood.

It is generally known that the intra-uterine life presents a notable disparity in the same zoological group, and sometimes in nearly related species. If men constituted a genus, it would be very strange if they were exempt from this law, and that no differences should have been observed, as they certainly would have been, between groups. These differences may indeed exist to a certain extent without rising to a specific character, for they are observed in our races of domestic animals, where they appear to bear some relation to stature. Gestation lasts sixty-three days in large races of dogs; from fifty-nine to sixty-three in the small. This is the period observed in menageries for the gestation of the jackal, the wild stock of the dog. But it rises to something over a hundred days for the wolf, however nearly related it may morphologically be to some canine races.

The period of lactation is very variable as to duration in different human peoples. Without even going beyond France, we should have no difficulty in giving examples of such differences, in which the maximum would almost double the minimum. It is evident that in this case manners, customs, etc., play the most important part, and that the question of races scarcely enters at all. With the Negroes, lactation lasts, as a general rule, for two years, and the period is quite as long in all oriental populations. It lasts for five years in China. But as M. Morache tells us, the Chinese mother only prolongs it in order to retard the recommencement of the monthly courses, which, in this fertile race, is rapidly followed by a fresh pregnancy. There is nothing surprising in the possibility of such prolonged lactation. It is generally known that the secretion of the milk is supported by its use. Amongst ourselves, according to the evidence of Desormeaux, one nurse will sometimes suckle three or four infants in succession.