290 BIOLOGICAL ASPECTS OF HUMAN PROBLEMS 



various practical ways to protect people against the 

 more obvious causes of infectious disease. But 

 mere knowledge of the causes of disease on the part 

 of the people and wise health regulations on the 

 part of the government will not necessarily suffice to 

 improve the average bodily efficiency of the mem- 

 bers of the community. To secure this it is essential 

 that there should be intelligent and continued efforts 

 on the part of a large percentage of the population 

 to practice self-control in regard to many habits of 

 life that cannot fall within the scope of even the most 

 paternal government. The physical health of the 

 human race is, in a remarkable degree, under the 

 control of the people themselves. There can be 

 little reasonable doubt that a far more hardy and 

 enduring race is capable of deliberate development. 

 It remains to be seen whether the individuals who 

 constitute nations will make the necessary sacrifices 

 to bring about this improvement. 



The theory of evolution indicates that man 

 emerged in distant times as the king of animal forms 

 after a long period of development in which all 

 competitors became gradually separated by an im- 

 mense gap. The lead so gained over other animal 

 life is so great in respect to bodily structure and 

 mental endowment as to make it unthinkable that 

 man should ever be displaced by forms descended 

 from types now inferior to him. The developmental 

 contest is now one between different races of men, 

 and it is evident that certain nations, especially the 



