terioration until the neo-agricultural period was far advanced-that is, until the present time. Nowadays, because food is so soft, mastication is to a great extent unnecessary; consequently the teeth are growing smaller. and weaker. The third molar is "practically always degenerate," and not infrequently absent. The jaw, also, does not grow to its pristine or even to what may be termed its normal size. In fact, the teeth which have diminished in size cannot find room in the diminutive jaw to take up their natural anatomical positions. This deterioration, accompanied by a tendency to decay, has of recent years gone on apace. Dietary dental diseases are now extremely prevalent among the most civilized or among those living under the most highly civilized conditions, as is also dyspepsia, largely due to improper mastication. Nowhere is so much soft pap food eaten and consequently so little mastication and insalivation required as in America. In fact, cereals and many other foods in this country are offered for sale partially predigested; they neither give the teeth work, nor do they excite the salivary glands or the digestive functions to activity. May not this be a chief reason for the prevalence of digestive troubles and for the dental caries, pyorrhea alveolaris and other diseases of the teeth among Americans? It is true that the teeth of Americans compare favorably with those of the inhabitants of other countries, but this is due to art and not to nature. The American dentist is the most ingenious and, on the whole, the most efficient in the world. But his numbers, his skill and his prosperity all show that his services are continually in demand, and that he has gained his proficiency chiefly because he has been given every opportunity to keep in constant practice. Moreover, since the conditions which are bringing about the degeneration and deterioration of the teeth and the subsequent disorders of the digestive system are growing steadily more prevalent, the future in this respect is threatening. SUMMARY OF THE EVOLUTION OF THE TEETH AND DIGESTIVE SYSTEM. The situation may be summed up as follows: The teeth of the primates closest to man, and of very early man himself, were sounder than at the present time because they were kept in constant use. With the coming of agriculture and cookery, the teeth lost a good deal of their importance. Before this time they were absolutely essential to life; after this period, although it might be extremely inconvenient and prejudicial to a good state of health to be without teeth, they were not absolutely essential. As time went on, teeth lost more and more of their importance as a means of sustaining life until, at the present time, food is so prepared and cooked that the teeth are not called upon to exert any strenuous action. Grinding mastication is unknown. Generally speaking, our food, including meat, is soft; consequently the teeth tend to decay, from lack of exercise and from other causes, at an early age. Therefore, it is true that although we have gained much by agriculture and cookery, we have lost much. We now eat a large amount of food which is not good for us, simply because it is agreeable and can be eaten without mastication; we eat too much food and a considerable quantity of unsuitable food. Our teeth go, and we suffer from indigestion, especially from that form known as intestinal stasis. No kind of food predisposes to and causes intestinal stasis to such an extent as soft, partially digested, unmasticated food. The outstanding features of the existing dietary is the concentration of diet, and the soft forms of food ingested. These lead to constipation and indigestion, the curse, it may almost be said, of modern life and especially of life in cities. Overeating is also encouraged. Moreover, if this sort of soft diet is indulged in for any length of time, the digestive organs deteriorate like the teeth from lack of use, and a thoroughly vicious circle is established. Changes in the Mammary Function Due to the Artificial Feeding of Children. The artificial feeding of children will be mentioned here, but as the subject of bringing up infants on the bottle is adequately considered in Volume III,' it will be superfluous to dwell on the matter at length. In the precibicultural period, and among precibiculturists now extant, the theory of the survival of the fittest is an actuality. In former times, if a mother could not suckle her child, it was inevitably doomed to death. If a mother died during childbirth, the infant was deliberately destroyed. Consequently, by the elimination of those unfit to bring up children, the women remaining were in every respect admirably adapted for the purpose. After the domestication of lactating animals, mothers who for one cause or another were unable to nurse their children could rear them by artificial feeding. A beginning was thus made of the lowering of the standard of mammary function, which has now approached a serious condition. The civilized woman of the present day is less well equipped by far than her primitive sister, so far as her maternal functions are concerned. A distaste to or even aversion to the nursing of children is also becoming more and more evident among all classes of society. In view of these facts it appears within the bounds of reason to foresee a time when the mammary function will atrophy and the majority of women will be. physically incapable of feeding their progeny at the breast. 1 Chapter XXV. GENERAL SUMMARY The chief fact taught by an investigation of man's dietetic past is that food has been a most important factor in the evolution of man. Three events mark the dietary influence on this evolution-the discovery of cooking, the advent of the agricultural era, and the domestication of animals. All of these innovations, by profoundly influencing the diet of man, have changed his manner of life in all respects. In fact, food brought about the ascent of man to a certain level upon which his present lofty position has been built. While civilization, based upon the results of cookery and cultivation, has been a blessing to mankind, it has not been an unmixed blessing regarded from the standpoint of health. In early times, the food of our ancestors was such that much of it required vigorous mastication, with the consequence that little starch was taken into the stomach in a crude form. At the present time, the reverse is the case; a very large amount of practically pure starch is ingested, and owing to its soft consistency and the consequent lack of mastication and insalivation, slips down into the stomach in a state totally unprepared for digestion, giving rise to various disorders and to malnutrition. This condition is particularly true in the case of infants. The supply of sugar has also increased and is eaten to an inordinate extent. This, taken in connection with the augmented consumption of vegetable food, gives rise to the conclusion that the present generation is likely to suffer from the undue consumption of both starch and sugar. No dogmatic statement can be made as to the relative values of animal and vegetable food as articles of diet. Since men have lived in good health as vegetarians or nearly vegetarians, and also solely upon meat, these examples do not prove the point. Climate has a great influence on the nature of a diet; occupation is a factor that must be considered, and heredity is not a wholly negligible quantity. In a general way, it may be said that animal food appeases hunger more thoroughly than a vegetable diet, and satisfies it for a longer time. It gives more stay to the stomach and has a more stimulating effect upon the system generally. In spite of the fact that man is descended from the ape, and that the ape is more frugivorous by far than carnivorous, the fact remains that the small size of man's stomach, due possibly to his erect posture, demands a concentrated diet, and this diet would seem to be best supplied by meat. Cookery affects the relative values of animal and vegetable foods in oppo site ways, with regard to mastication. Cooking coagulates the albumen of animal tissues, hardening it so that mastication may be necessary; cooking of vegetables does away with the need for mastication. It cannot even be argued that either animal or vegetable food is the natural diet of man, for while his ape ancestors did not eat much flesh, at one time of his early career as a human, man was more carnivorous than frugivorous. The present conformation of his jaws and teeth, the result of an evolutionary process, does not single him out as especially adapted for a vegetable or an animal diet. Whatever primitive man may have been considered from the dietetic standpoint, he is now a mixed feeder in temperate climates. Descending from ancestors whose diet for long ages has varied in the temperate zone, man would naturally find a varied diet best suited to his needs and to his taste. His anatomical history also shows that his digestive system is highly adaptable to these variations, and is capable of being modified to almost any extent. His adaptability affords an explanation of why he has fallen into the routine of the existing civilized mode of diet. Eating food of soft consistency, which is the universal habit, has had and is having an injurious effect upon his jaws and teeth, upon his salivary secretions, and upon his digestive system. He should revert to some extent to the food of his simian ancestors-raw vegetables and fruit-which would afford plenty of exercise to his masticatory, salivary and digestive organs. A simple diet is in the main the ideal one. If he continues to eat soft, cooked foods-and it does not seem very likely that he will not-then in the course of time it may be expected that a type of person will be evolved capable of dealing with the quantity and kind of food which our ultra refined civilization has decreed that we shall consume. Perhaps it is possible that we have come to the end of our progress in the direction of diet, and that the human race will be the better for going back to the simple diet of our ancestors. It must be borne in mind that extreme luxury in diet has been noted more than once in the history. of the world with the Persians and Romans, for example. Afterwards a period of comparative simplicity has ensued, until a climax has been again reached. The acme of dietary excellence was attained not long after the age of agriculture, cooking, and domestication of animals came in. Since then the increase of population, industrialism and other concomitants of advanced civilization have made further dietetic changes necessary. At the present time, the situation must be met in the best ways possible. The chief object of this chapter has been to point out and lay stress upon the fact that man's evolution has been greatly dependent upon the evolution of his diet, and it is to be hoped that this object has been fairly well attained. REFERENCES 1. CAMPBELL, HARRY. Sutherland's System of Diet. 2. SCOTT ELLIOTT. Prehistoric Man. 3. HOLMES. Convolution of Animal Intelligence. 4. SKEAT and BLAGDEN. Pagan Races of the Malay Peninsula. 5. TOZER. History and Geography. 6. CONSTANTIN and Bois. Rev. Gen. Bot. 7. BRINTON. Myths of the New World, 1868. 8. DU PRATZ. Hist. La., 1763. 9. BANCROFT. Nat. Rac., 1882. 10. HODGE. Am. Anthrop., 1893. 11. BRADFORD. Hist. Plym. Plant., Mass. Hist. Soc. Coll., 1856. 12. FISCHER. Arch. f. Anthrop., 1909. 13. Popular Science Monthly. April, 1898. 14. BABCOCK. Historical Notes on Alcohol. 15. PELLEW, DR. C. E. Appleton's Popular Science Monthly, June and July, 1893. 16. RICE, CHAS. Dining and Its Amenities. 20. WRANGELL. Expedition to the Polar Sea, 1844. 21. HEAD, F. B. Journeys Across the Pampas, 1828. 22. HEAD. Odontological Society's Transactions, ii, New Series. SCHOOL OF MEDICINE AND PUBLIC HEALTH HARVARD UNIVERSITY LIBRARY |