Popular Science Monthly/Volume 86/April 1915/Racial Element in National Vitality
|RACIAL ELEMENT IN NATIONAL VITALITY|
By Dr. CHAS. B. DAVENPORT
COLD SPRING HARBOR, N. Y.
OUR population is made up of such a variety of racial elements that it is hardly possible to make any statement about it as a whole that is both true and significant. Especially is this so in the field of statistics. When we say the death rate in the United States is 15.0 for the registration area, the number may be very accurate; but is it very significant? It throws together data of partly black states and those of nearly pure white: those of the slums of great cities with masses of recent immigrants and those of Kentucky. We have a number, to be sure, and one that we can compare with numbers similarly derived from other countries; but, aside from affording facts for almanacs, I conceive that such a number has little significance biologically or scientifically. I want as my contribution to this discussion to point out how widely different in vitality the races of the United States are. And first, it is necessary to point out that for the most part we use the term race too narrowly. I will use it collectively for the possessors of a racial (i. e., inheritable) character. Such are potentially members of a race; they may easily become actually such in consequence of a certain amount of isolation or inbreeding. To illustrate the fact that many traits that we think of merely as variations are really racial traits, we may consider eye color. If I ask a brown-eyed person whether he got his brown eyes from the mother's or the father's side of the house, he takes no umbrage at the inquiry and informs me if he knows. But if I ask an inhabitant of the island of Raratonga who prides himself on his race purity whether he got his brown eyes from the mother's or the father's side of the house, he feels at once insulted. His brown eyes he recognizes as a racial characteristic. As a matter of fact the brown eye color is a racial characteristic in both cases, but persons of European origin are used to the intermingling of the brown-eyed and the races that are found in this country, and forget the racial significance. Similarly, if I ask a colored man of our south whether it was from the father's or the side of the house that he got his light color, he answers me without objection, but if I should ask any of this audience whether they got their white skin color from the father's or the mother's side, they would naturally take exception to the inquiry. All of our inheritable characteristics have, indeed, the essential traits of specific characters.
Beginning with the generally recognized races, as is well known the mortality of the negro is very different from that of the white. Thus, the census report gives the death rate among whites as 17 per 1,000 and among negroes 28 per 1,000, or nearly double, and for every 100 white children per 1,000 who die under 15 years, there are 150 negro children. Now the interpretation of this result is not simple; in part the higher death rate of the negro is due to economic conditions that are, however, determined largely by racial traits; but, in part, it is probably due to the fact that the negro is not yet adjusted to the white man's civilization. Especially does this folk of jungle origin wither away in our large cities. Similarly, the death rate from tuberculosis is 3 times as great among our Indians as among the whites, and deaths from measles are proportionally greater among Indians than whites. Clearly the grand races differ tremendously in their vitality.
I know there are those who deny that there is such a thing as inherited resistance to disease. But there is at least a family liability to or immunity from various diseases, such as tuberculosis. It is easy to find in our records families in which 10 out of 12 or 14 deaths in a family have been from tuberculosis; as it is easy to find families of which none of the 10 or more members who have died have died of this disease, even when they have died at mature age, and, like practically every person, exposed to the disease. I think, then, we must recognize that non-resistance to tuberculosis is a family trait; and it may be characteristic of a whole locality, provided that locality (like southern California) has attracted many representatives of the non-immune race. We find indeed that, despite its salubrious climate, consumption is a much more common cause of death here than in most other sections of the country; and the high incidence of tuberculosis is found in the children and grandchildren of those who went to California for their health.
Again cancer is a disease whose rate of incidence varies in different parts of the country; it is highest in the state of Maine. Now, I have no doubt that this is due to the presence of one or more races in Maine which are non-immune to cancer. I know that many medical men do not respond favorably to the contention that there is a racial cancer diathesis in man. To be sure, it has been repeatedly demonstrated that such races occur in mice and such human families as we have studied yield the same result as the mice studied and indicate that resistance to cancer is a positive (dominant) trait and that non-resistance appears in the children only when both parents belong to a non-resistant race. And this result is commonest, other things being equal, where cousin marriages are commonest, because that makes it probable that if one parent belongs to a cancer race the other—the cousin—will belong to the same cancer race. Now in rural Maine, cousin marriages are extremely frequent—especially in the islands off the coast, and here we have the conditions for the result—the high incidence of numbers of the cancer race in an inbred community.
Again Huntington's chorea is a fairly common cause of death in certain localities, and it is a racial character as truly as are brown eyes. For it does not skip a generation, and affects ordinarily half of the children of any affected parent. The vitality of Greenwich, Connecticut, like Suffolk County, Long Island, was formerly measurably affected by the presence in many of the old stock of that town of this racial characteristic.
Hemophilia, likewise, is, or was, a striking cause of death in certain localities, like a town of Sullivan County, Pennsylvania. It occurs in males chiefly, rarely in females, except in the case of the marriage of two persons who belong to the same race; and it ordinarily alternates in its appearance in the generations. It is an ordinarily sex-limited character. Its high frequency is due to the fact that persons with this trait settled in Sullivan County and have left descendants there.
It might appear from what I have said above that heredity has to do only with diseases or unfortunate mental conditions, but for every liability to disease there is resistance, and for every mental defect or weakness there is mental strength; and heredity has just as much to do with the reappearance of these strong characters in the offspring. I have laid most stress upon diseases, simply because we think so much in terms of them.
Now, in this brief address, I have alluded to instances merely where the death rate depends on the presence in the community of a disproportion of persons belonging to races that show immunity or susceptibility to particular diseases. I think it can not be doubted that most causes of death have, at least, an hereditary factor, and so we may draw the conclusion that the morbidity and the mortality of any community or commonwealth is to a large extent determined by the racial elements present there of general or specific resistance or liability to morbific agencies.
Finally, statistics tend to cover over causes. Indeed the statistical method abandons as hopeless the attempt to analyze causes and deals only with results. But what we are interested in is, after all, causes; and so far as possible the causes should be isolated and studied separately and, in this paper, I have laid stress on the importance of the racial element as a cause of variations in national vitality.