This section is from the book "Man: A History Of The Human Body", by Arthur Keith, Sir. Also available from Amazon: Man: A History Of The Human Body.
Some years ago everybody was alarmed by the statement that our national physique was in process of decay. The question whether this was the case or not could have been decided with ease if exact measurements had been made of the generations which have lived in this land before us; but unfortunately facts relating to the ancient British are very few. Professor Karl Pearson with his pupils made a searching enquiry regarding the stature of prehistoric people, and came to the conclusion that" the average Englishman of to-day is certainly not behind his Anglo-Saxon ancestor." Indeed the evidence is almost positive that modern men and women are taller than their forerunners of a thousand years ago, but the difficulty of making a dogmatic statement is increased by the fact that in all times stature has varied with class. Galton found that the men of the commonalty of modern England had a stature of 1,700 mm. (5 ft. 7 in.); the middle class (Pearson) 1,728 (5 ft. 8 in.); the Oxford students (Schuster) 1,740 (5 ft. 8-6 in.).
How much the higher stature of the well-to-do classes is due to better breeding and how much to better feeding is not determined, but all the evidence points to inheritance as being the more important factor. Modern statistics leave no doubt about well-nourished boys and girls being taller and heavier than children of a corresponding age who are less well-nourished and cared for. We have no evidence, however, to show that under-feeding will undermine the growth-energy of a race; underfeeding stunts the individual but so far as we know leaves the stock unaffected. That, however, is no reason why any one should be underfed.
When we come to enquire into other features of our bodies we have less reason to form an optimistic opinion. There seems to be at least two parts or regions which are in a state of change. The first of these concerns the whole system of mastication—the teeth, the jaws, the face, and throat. The second includes the lower part of the bowel—the appendix— the caecum and colon. These parts belong to the commencement and to the termination of the alimentary system. There is every reason to suppose that the degenerative changes in these two regions of the body are manifestations of a common cause; the races in which we find irregular teeth, contracted jaws, constricted throats are also the races who are subject to diseases of the appendix, caecum and colon.
We may conceive two things to have happened (1) That these changes in the jaws, teeth and colon are simply the appearance of new racial features; we are in the habit of saying such characters appear spontaneously because we have not yet discovered the cause of their origin, (ii) It may be that these changes which are taking place in the national physique are due to an alteration in the kind of food on which we modern peoples live. Our alimentary system was originally evolved to cope with the raw food of primitive man. Our digestive system may be unbalanced by the nature of our diet. Think for a minute how we stand in the matter of food as compared with the ancient Britons ! To-day the world empties her lap into England —wheat, flesh and fruit. Cooking and seasoning have altered the nature of a diet which in its concentrated nature and abundant supply forms a revolutionary change in the methods of life. The ancient Briton had only an uncertain and crude supply gathered from small field-patch, wood or river. Cooking is an art which comes with civilization ; primitive man may have roasted or broiled his meat; he probably never boiled either his meal or vegetables.
The evil condition of modern teeth is notorious ; dental decay of course is preventable by strict cleanliness. In the skulls of Britons who lived in these islands a thousand years ago and upwards, it is usual to find the teeth sound, their crowns worn down by use, the palate well spread; the nasal cavities well formed, the cheek-bones well set. We have no reason to suppose that our remote ancestors used tooth brushes. It is true that bad teeth are also found in ancient European races ; for instance, in the Tilbury man, one of the earliest of human remains yet discovered in England, many of the teeth have been lost during life; even in the European of the glacial period, dental disease may be seen. Such a condition was rare in prehistoric times ; now it affects all. The teeth of prehistoric races of mankind are worn ; the crowns are eroded by the act of chewing food which must have been tough and required vigorous mastication. In modern skulls of even quite old men it is usual to see such teeth as have remained sound in the jaws, quite unworn. We may draw one conclusion with the utmost certainty from the comparison of ancient and modern teeth—that the ancient and modern dietaries were totally different in nature. The old required vigorous mastication ; the modern does not. We may also infer that the disturbance which is so widely affecting our teeth, jaws, nose and face is a consequence of that change in dietary. The writer must have examined at one time or another over 100 skulls of Neolithic people—people who lived in Britain 4,000 years ago or more, and has only seen one with a contracted palate and irregular teeth. Although contraction in the width of the face, narrowing of the palate, obstruction of the nose and throat are extremely common in modern children and adults, these conditions are never seen at birth. They become manifest as the permanent teeth erupt and come into use. The condition we are discussing is therefore not present at birth. While it cannot then be called hereditary it is possible that a susceptibility or tendency may descend from one generation to another in some families. All we can say at present is that a retrograde change does appear to be at work on the faces and jaws of highly civilized peoples and that the change is probably due to diet. Our diet has been altered but we can hardly expect nature to provide us at once with a mouth and teeth suitable to the new conditions of living. The contracted palate appears to be Nature's way of bringing our jaws into harmony with the kind of work we are giving them to do. Instead of waiting for Nature to act it would be more practical perhaps to alter our diet to suit the dental system we have inherited. Mention has already been made of the fact that the third molars in highly civilized people may be very late in erupting or may never cut the gum. The third molars are often deformed or much reduced in size.
 
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