26 THE PROTEIN ELEMENT IN NUTRITION 



increases more rapidly than where it is scarce and dear."* With 

 regard to the function of animal food in man's e volution, Crichton- 

 Browne states : " In whatever direction the temper of the mind 

 be bent by animal or vegetable diet, it is clear that animal food 

 has played a decisive part in human evolution, and that the 

 craving for it has largely contributed to the advance of civiliza- 

 tion. That craving led to the invention of weapons and traps 

 of many kinds, to the acts of fishing and hunting, to migration, 

 travel, and adventure, to the patient pursuit of the taming and 

 domestication of wild creatures, and to provision for their wants ; 

 and success in the satisfaction of that craving has always been 

 followed by advancement alike in the arts of war and peace. A 

 diet rich in protein makes for physical and mental energy, and it 

 is not vegetable protein always poor in amount to the bulk of 

 the food eaten, difficult of absorption, and probably of special 

 and, from a nutritive point of view, inferior constitution but 

 animal protein that is required. It is animal protein that is 

 the true food of the brain and nerves, and hence all the more 

 energetic races of the world and those most distinguished for 

 intellectual capacity have been meat- eaters." 



In connection with this most interesting subject, the brilliant 

 work that has been done by Dr. Harry Campbellf in adding to 

 our knowledge of the changes man's diet has undergone from early 

 times is of first importance, and demands careful consideration. 



Of the three classes of the mammalia as regards diet the 

 frugivora, including such animals as the squirrel, rat, and the 

 monkey, are mixed feeders. Being generally more intelligent 

 than the herbivora, and gifted with considerable prehensile 

 powers, they are able to pick and choose their food, selecting it 

 in its more concentrated forms, such as seeds, nuts, fruits, eggs, 

 small birds, lizards, grubs, and the like. " Man, now essentially 

 a mixed feeder, belongs by virtue of his descent, as might be 

 expected from his high mental and bodily development, to the 

 frugivora." 



With regard to the food of evolving man, Campbell points out 

 that " the products of the uncultivated vegetable kingdom are by 

 themselves totally inadequate to supply man's nutritive needs." 

 The fruits and vegetables of the present day are very different 

 from their wild and barely edible representatives of past ages. 

 They in their turn have undergone an evolution no less remark- 



* Sir J. Crichton- Browne, " Parsimony in Nutrition," 1908. 

 f Dr. Harry Campbell, " The Evolution of Man's Diet." 



