Why Health and Energy Vary from Place to Place.—We saw on an earlier page that health depends on (1) inheritance, (2) food, (3) sanitation and medical practice, (4) climate, and (5) bacteria. We must now inquire how far each of these explains the variations in health from place to place. Inheritance doubtless plays a part, but not the main part, for in Fig. 22 it seems to have little effect. The people who are insured are of essentially the same kind in all parts of the United States, the vast majority being of North European descent. There is no reason to think that those in Iowa have any greater inheritance of energy than those in South Carolina. Food, sanitation, and medical practice are likewise highly important, although among the people who can afford to pay for life insurance practically all have a diet so varied that few deaths are due to malnutrition. The disadvantages due to the relatively poor medical care and sanitation in South are partly offset by the nerve-racking life in the northern manufacturing cities. Moreover, these disadvantages are in themselves partly the result of lack of energy. Hence only part of the differences in Fig. 22 can be due to this group of causes.
The effect produced by climate can best be measured by making a map showing the degree of energy that people would have in different parts of the United States if their health depended wholly on climate. Such a map, Fig. 23, shows that the best part of the. United States is the northeastern quarter. Although the winters there are too cold and the summers often too hot, these disadvantages are partly compen sated for by the variability of the weather and the stimulus that comes from the frequent days that approach the ideal at almost all seasons. The Pacific coast is likewise highly favorable. So far as temperature alone is concerned it is almost ideal in the sections close to the ocean, for clays averaging below 40° or above are almost unknown. The, main disadvantage is probably the infrequency of changes. Notice how the climatic energy falls off in the southern United States. Note also the area of somewhat low energy extending toward Nevada and the relatively low band covering the whole Rocky Mountain area. Of course even the worst conditions in the United States are decidedly stimulating and healthful compared with tropical regions. For our present pur pose, however, the important point is that the map of climatic energy is almost like that of health on the one hand and like that of civilization on the other. The three appear to be closely connected.
As to the relation between bacteria or other parasites and the dis tribution of health there can be no question. But the hookworm thrives only in relatively warm regions, and seems to be shorn of much of its influence if people are well nourished. The malarial bacteria may he transmitted to man wherever the anopheles mosquito thrives, but their ravages are serious chiefly in warm regions. The yellow fever
bacteria are limited to warm regions where the stegornaria mosquito flourishes. hundreds of other parasitic forms vary in virulence from place to place, and many of these variations are climatic. From all this it appears that inheritance, food, sanitation, medicine, and bacteria all have a great effect upon the geographical distribution of health and may cause variations from season to season. Moreover, epidemics, a new diet, the introduction of sanitary measures, and the discovery of new methods of eliminating bacteria arc all capable of making great changes in the health and hence in the energy and business capacity of a region. Nevertheless, the effect of all these other factors is greatly influenced by climate and weather. The air, as it were, furnishes the background upon which the other factors play their part.
Climate, Health, and Civilization in relationships between health and other conditions which are indicated in the United States seem equally clear in Europe. Fig. 57 (Chap. XVII) represents the distribution of the climatic conditions which appear to give the greatest energy. Fig. 58 shows the distribution of health on the basis of the mortality statistics of the various countries of Europe. All the statistics have been reduced to what is known as a standard population, so that variations in the percentage of children and old people make no difference. It ha's been impossible to eliminate the effect of manufac turing and of crowding into cities. If this could be done it would make the manufacturing countries around the North Sea appear even more favored than now. Fig. 59 gives the distribution of civilization according to the opinion of fifty eminent authorities.
The significant feature of these maps is that all three are essentially the same. Notice how they shade off in every direction from the North Sea. Note also the three projections of good conditions toward Italy, the Black Sea, and the Baltic. Take away the titles and almost no one could tell which map is which. Such close similarity seems to mean a correspondingly close connection between climate, health and civili zation. There is only one way in which this connection can be estab lished. Health may he, and is, influenced largely by both climate and civilization. And good health undoubtedly tends toward the advance ment of civilization. Climate also may perhaps have some direct effect upon civilization. But neither health nor civilization can have the slightest effect upon climate. Therefore climate seems to be the foundation; the general distribution of health is apparently clue to cli mate; and the distribution of civilization appears to be greatly influenced by the health and energy of the people. A high civilization will, of course, react still further to improve the health of the people, but appa rently it would not thus react to so great an extent unless the people already possessed energy because of their good climate.