THE DESIRE FOB FOOD IN MAN 567
inherited instinct were evolved. The " survival of the fittest " involves the extermination of what we may charitably denominate " the others/' But the nobler elements of modern human sentiment demand the pro- tection, not to say the cherishing^ of the unfit; who thus survive and hand on their legacy of ill adjustment to another generation. Further- more^ in these days of the supremacy of certain qualities of gray matter^ such as shrewdness and ^'business faculty/' and of human tools, the industrial (non-human) machines^ it is far from being the case that the man who is muscularly fittest has the best immediate chance of survival, even if we leave all the works of human altruism out of consideration. By various means is the inevitable punishment for physical degeneration greatly delayed; and so vital a matter as a lack of adjustment of fuel or building material to body requirement, in spite of its ultimately more or less serious consequences, may go long with little remark. For instance, where in the '* state of nature " does one find an over-fat animal ? The struggle is too keen, to permit such to survive. Yet the over-fat human is by no means an uncommon phenomenon.
2. Furthermore, the fact that serious and rather common errors in nutrition are considered by physicians as important contributing causes to diseases which usually develop in middle life, and which re- sult in long morbidity of insidious development lacking in the spec- tacular element produced by sudden mortality — this fact of the long delay of punishment tends to obscure the nature of the error. It is true, however, that having accomplished something toward the con- quest of bubonic plague and cholera, typhoid and even tuberculosis, we are beginning to ask ourselves why it is that certain diseases are so constantly on the increase. For answer (in part, at least), it is more and more frequently mentioned to us, that overfeeding, that is, feeding too much protein, or too much fuel, or both, is often a predisposing factor of some importance in such cases as these: kidney and gall- bladder infections and infiammations, certain kinds of disturbance of the circulatory system (e. g., arteriosclerosis, high blood-pressure dis- eases), various infections of skin or mucous membranes (from a com- mon cold to the most serious eczema cases), and even possibly cancer.'
3. The voluntary muscles, which in the activities of the human animal in a "state of nature,*' use probably 75 per cent, of the fuel
< The author does not wish to be understood as making the claim that these diseases — e, g,, gall-stones, Bright 's disease, diabetes, ete. — always, or often, have overeating as a sole or chief cause, even though it is so frequently men- tioned as one of the causes. It must be remembered, too, that most points regarding the relation of diets to disease are still more or less in the controversial stage. Moreover, it must not be forgotten that the dangers of under-nutrition (espedallj in persons under 30 years of age) are equally serious with those of overeating.
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