Effects on Different Races
Only by generations of natural selection could we expect to make man immune to the evils of bad air. The robust Indian and the Negro, whose races, until the last generation or two, roamed in the open, fell easy prey to tuberculosis as soon as they adopted the white man’s houses and clothes. The Anglo-Saxons who have withstood the influence of indoor living for several generations have, probably by the survival of the fittest, become a little better able to endure it, while the Jews, a race which has lived indoors longer than any other existing race, are now, probably by the same law of survival, the least liable to tuberculosis, except when exposed to especially unfavorable conditions of life.
Compensation for Civilization
But we, of this generation, can not afford to wait for natural selection to fit the race to an indoor environment; hence the supreme importance to us of air hygiene. We must compensate for the construction of our houses by insisting on open windows, or forced drafts, or electric fans, or open-air outings, or sleeping porches, or the practise of deep breathing, or all of these things.
Clothing Artificial
In the same way, clothing has protected our bodies from the cold but enervated or constricted them as well. The aboriginal tribes, even in cold climates, seldom used clothing. The Eskimo is an exception. The tribes toward the South Pole in similarly cold climates often have little more clothing than a blanket which they hang over their shoulders toward the wind. The weak, pale skin—to whose lack of adaptability we owe the chilling preceding a cold—the bald head, the distorted foot, the corns upon it, the cramped waist, are among the results of clothing ourselves wrongly. Hence we are discovering the need of restoring, as far as we can, the original conditions by making our clothes more light, more loose, and more porous, and, when possible, by taking the “barefoot cure,” or the air bath.
Cooking Artificial
We come next to foods, and note that civilization has invented cooking and artificial foods. These inventions have greatly widened the variety of man’s diet, but the foods of civilization are largely responsible for the decay of our teeth and the abuse of our digestive and eliminating organs.
Soft Foods Artificial
Judging from man’s teeth and digestive apparatus as well as his general kinship to the anthropoid ape, it is reasonable to believe that, before fire was discovered, man was primarily a frugivorous animal, whose ordinary diet consisted of fruits, nuts, and tender shoots. While man still uses these fruits, nuts, and salads, his chief reliance is on prepared food, bread, butter, meat, and cooked vegetables. The diet of our progenitors must have been largely one requiring chewing, consisting, as it did, of hard fruits and stalks and perhaps also grains and flesh. Observation of manlike apes shows that they chew their food more thoroughly than man. Doubtless nuts constituted a considerable part of primitive food and required cracking by the teeth. The work we now do in flour-mills or the kitchen or with the knife and fork, was then done with the teeth. We even have our cook mash our potatoes and make puddings and pap of our food after it reaches the kitchen. Having already shirked most of the task of mastication by softening and cutting our food before it reaches our mouths, we shirk the rest of it by washing it down with water, or worse. An Italian dentist, who has had a wide range of observation, says that the knife and fork have committed “unpardonable crimes” by robbing the front teeth of their work of cutting. He sometimes prescribes for loose teeth the task of cutting a pound of bread daily. Whether any of it is swallowed or not is not important, but he insists that it must be cut by the teeth.