XII. THE EVOLUTION OF MANKIND AND ITS FUTURE 



Stature of army recruits or others is known to have increased ahnost 

 steadily since 1792 in Switzerland, 1836 among Harvard students, 1841 

 in Sweden, 1852 in Denmark, 1855 in Norway, 1863 in Holland, and 

 1885 in Japan (103). From measurements of about half a million 

 males of twenty years from 1892 to 1926, the mean height of Japanese 

 was found to have increased by 3.23 cm, the increase being steady 

 and uniform from year to year (104). 



In this connection, another most remarkable fact should be cited. 

 During almost the same period of time the resistance to tuberculosis 

 has been increased steadily in man. The disease has shown since 

 1849 a steady decline, along with approximate mortality rate, for the 

 United States and for England and Wales, during the same period (105). 



The dramatic change in the relation of the tubercle bacillus to 

 man took place over most of the Western World during the same 

 100-year period. In other words, mortality rates began to decrease in 

 Europe and North America around 1850 and they have continued to 

 decrease steadily eversince, in conformity with the increase of the 

 stature, except for short and local interruptions in the downward 

 curve during and after the first and the second World Wars as shown 

 in Fig. 38. It should be noted that the rate of decrease in tubercu- 

 losis mortality had already reached its maximum slope around 1900, 



iw-i 



1939-45 War 



1945 



FiK rs. Tuberculosis all forms, under 15 years, England and Wales. 

 1904-1945. Reproduced from Dubos, R. J. : Science in 

 Progress, Sixth Series, 1949. 



