Thus, the anthropoid apes are brachycephalic, but all known types of Palæolithic man are dolichocephalic. Matched against the apes, the long-headed Negro would therefore seem to be the most humanly specialized stock. Compared however with the fossil human forms, the Negro is the most primitive in this feature, and the Mongoloid and Alpine Caucasian could be said to have evolved the farthest because their heads are the roundest. Yet their degree of brachycephaly is approximately that of the anthropoid apes. To which criterion shall be given precedence? It is impossible to say. Quite likely the round-headedness of the apes represents a special trait which they acquired since their divergence from the common hominid ancestral stem. If so, their round-headedness and that of the Mongoloids is simply a case of convergent evolution, of a character repeating independently, and therefore no evidence of Mongoloid primitiveness. Yet, if so, the long-headedness common to the early human races and the modern Negroids would probably also mean nothing.

It is even clearer that other traits have been acquired independently, have been secondarily evolved over again. Thus the supraorbital ridges. When one observes the consistency with which these are heavy in practically all Neandertal specimens; how they are still more conspicuous in Pithecanthropus and Rhodesian man; how the male gorilla shows them enormously developed; and that among living races they are perhaps strongest in the lowly Australian, it is tempting to look upon this bony development as a definite sign of primitiveness. Yet there is an array of contradicting facts. The youthful gorilla and adult orang are without supraorbital development. The male gorilla has his powerful brows for the same reason that he has the crest along the top of his skull: they are needed as attachments for his powerful musculature. They are evidently a secondary sex character developed within the species. So among fossil men there seem to have been two strains: one represented by Pithecanthropus and Neandertal man and the Rhodesian race, which tended toward supraorbital massiveness; and another, of which Piltdown man is representative, which was smooth of forehead. Among living races the Asiatic Mongoloids lack marked supraorbital development; the closely related American Indians possess it rather strongly; Caucasians and Negroes show little of the feature; Australians most of all. Evidently it would be unsafe to build much conclusion on either the presence or absence of supraorbital ridges.

Perhaps these instances will suffice to show that even the mere physical rating of human races is far from a simple or easy task. It is doubtful whether as yet it is valid to speak of one race as physically higher or more advanced, or more human and less brutish, than another. This is not an outright denial of the possibility of such differential ratings: it is a denial only of the belief that such differentials have been established as demonstrable.

37. Comparative Physiological Data

There is another angle of approach. This consists in abandoning the direct attempt to rate the races in anatomical terms, and inquiring instead whether they show any physiological differences. If such differences can be found, they may then perhaps be interpretable as differences in activity, responsiveness, endurance, or similar constitutional qualities. If the bodies of two races behave differently, we should have considerable reason to believe that their minds also behaved differently.

Unfortunately, we possess fewer data on comparative physiology than on comparative anatomy. The evidence is more fluctuating and intricate, and requires more patience to assemble. Unfortunately, too, for the purposes of our inquiry, the races come out almost exactly alike in the simpler physiological reactions. The normal body temperature for Caucasian adults is 37° (98.5 F.), the pulse about 70, the respiration rate around 17 or 18 per minute. If the Negro’s temperature averaged even a degree higher, one might expect him to behave, normally, a little more feverishly, to respond to stimulus with more vehemence, to move more quickly or more restlessly. Or, if the pulse rate of Mongolians were definitely lower, they might be expected to react more sluggishly, more sedately, like aging Caucasians. But such observations as are available, though they are far from as numerous as is desirable, reveal no such differences: temperature, pulse, respiration, record the same as among Caucasians, or differ so slightly, or so conflictingly, as to leave no room for positive conclusions. Certainly if there existed any important racial peculiarities, they would have been noted by the physicians who at one time or another have examined millions of Negroes, Chinese, Japanese, and thousands of Indians and Polynesians.

Apparently there is only one record that even hints at anything significant. Hrdlička, among some 700 Indians of the Southwestern United States and Northwestern Mexico, found the pulse to average about 60 per minute, or ten beats less than among whites. This would seem to accord with the general impression of Indian mentality as stolid, reserved, slow, and steady. But the number of observations is after all rather small; the part of the race represented by them is limited; and the habitat of the group of tribes is mostly a high plateau, and altitude notoriously affects heart action. Considerable corroboration will therefore be needed before any serious conclusions can be built upon this suggestive set of data.

There are other physiological functions that are likely to mean more than the rather gross ones just considered: for instance, the activity of the endocrines or glands of internal secretion. An excess or deficiency of activity of the thyroid, pituitary, adrenals, and sex glands affects not only health, but the type of personality and its emotional and intellectual reactions. For example, cretinism with its accompaniment of near-idiocy is the result of thyroidal under-development or under-functioning, and is often cured by supplying the lack of thyroidal substance and secretion. But this subject is as difficult as it is interesting; to date, absolutely nothing is known about endocrine race differences. It would be a relatively simple matter to secure first-hand information on the anatomy of the endocrine glands in Negroes as compared with whites; to ascertain whether these differed normally in size, weight, shape, or structure, and how. But this knowledge has scarcely been attempted systematically, and still less is any knowledge available in the more delicate and complex field of the workings of the organs. To be sure, theories have been advanced that race differentiation itself may be mainly the result of endocrine differentiations. There is something fascinating about such conjectures, but it is well to remember that they are unmitigated guesses.

38. Disease

Pathology might seem to promise more than normal physiology. So far as mortality goes, there are enormous differences between races. And the mortality is often largely the result of particular diseases. Measles, for instance, has often been a deadly epidemic to uncivilized peoples, and smallpox has in some regions at times taken toll of a quarter of the population in a year or two. Yet it is short-sighted to infer from such cases any racial predisposition or lack of resistance. The peoples in question have been free for generations, perhaps for their entire history, from these diseases, and have therefore not maintained or acquired immunity. Their difference from us is thus essentially in experience, not hereditary or racial. This is confirmed by the fact that after a generation or two the same epidemics that at first were so deadly to Polynesians or American Indians sink to almost the same level of mild virulence as they show among ourselves.