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.