DIETETICS 153 



movements of respiration, masticating food, shifting position, 

 maintaining the body-temperature, etc. 



Health may be maintained and work done on diets which 

 depart widely from the one which we have selected as a stan- 

 dard. Darwin found the Guanchos of South America living 

 exclusively on meat. Nansen and Johannsen, when seeking 

 the North Pole, lived for months on meat and blubber. Millions 

 of the inhabitants of India abstain from meat and meat-fat, 

 their diet consisting of rice, buttermilk, and a little fruit. In the 

 case of all persons with whom the price of food is an important 

 consideration, carbohydrates are preferred to proteins and fats. 

 Oatmeal is very much cheaper per unit of energy than meat. 

 A man may be a meat-eater or a vegetarian, although he is 

 probably unwise in overlooking the obvious teaching of his 

 teeth and digestive organs, which are those of an omnivorous 

 animal. His prehistoric human ancestors lived chiefly on the 

 harvest of their spears and tomahawks. If we insist upon 

 looking back still farther, we discern a cleavage of the race 

 into the arboreal fruit-eaters, which still retain pre-human 

 characters, and the more enterprising and energetic troglodyte 

 hunters from whom the human race was evolved. 



A man may vary his diet within wide limits. In- 

 numerable considerations lead certain individuals to desire to 

 depart from the diet which we have termed " normal " i.e., 

 typical of inhabitants of the temperate zone. One man rebels 

 against the expense of living ; he would fain reduce the quan- 

 tity and the cost of food. Another, having to traverse regions 

 in which food is scarce, wishes to ascertain the lightest, and 

 therefore the most portable, combination of its essential 

 elements. A third and he belongs to a much larger class 

 tormented with indigestion or harassed by gout, asks, " Why 

 must I consume things which give the stomach trouble, or 

 produce disagreeable and incapacitating after-effects ?" Many 

 circumstances prompt to experiments in diet. Much latitude 

 is undoubtedly allowed. But there are limits within which alone 

 health can be maintained and work done. It is of great interest 

 to ascertain exactly how wide these limits are ; and especially 

 important is it to find out the lower limit, the minimum 

 of food, and the minimum of each particular kind of food, 

 which will enable the human machine to work. The problems 



