THE EFFECT UPON HUMAN EVOLUTION 285 



vironment that the investigation of the endocrines promises to put 

 into our hands the instruments of the control of the future of the 

 nervous system. In general, meanwhile, the eugenist should 

 strive for raising the level of the endocrine potential, and dis- 

 courage its lowering. That means the encouragement of matings 

 in which all the internal secretion activities are reinforced. On 

 the other hand, those internal secretion combinations, generally 

 leading to a deficiency of all of them which produce types of 

 mental defectives, delinquency and crime should not be allowed 

 to occur. 



The Influence of Environment 



What suggestions now are there for the euthenist who would 

 control the influence of environment upon child culture. There 

 are certain pertinent facts and leads that are worth considering. 



In analyzing environment, one must distinguish sharply in the 

 jungle, the non-living factors from the living. For while the non- 

 living act upon the endocrines directly, the living act upon the 

 vegetative system, as a whole. The non-living factors are those 

 with the intimate scrutiny of which physics and chemistry have 

 busied themselves: food, water, air, light, heat, electricity, 

 magnetism. The living are the animals that prowl all over the 

 planet, the predatories spreading the gospel of fear. 



The dietetic habits of a person, for instance, are known to 

 have an influence upon the glands of internal secretion. Meat- 

 eating produces a greater call upon the thyroid than any other 

 form of food. In time this ought to produce a degree of hyper- 

 thyroidism in the carniverous populations. Pre-war statistics 

 concerning meat-eating in different countries show the greatest 

 meat-eating among the English-speaking groups, who all in all 

 must be admitted the most energetic. Mmt ^ Day per 



Countries Capita in Grams. 



Australia .>-.: 306 



U. S. of America 149 



Great Britain 130 



France ,.- 92 



Belgium and Holland 86 



Austria-Hungary 79 



Russia 59 



Spain sa 61 



Italy 29 



Japan 25 



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