XII. THE EVOLUTION OF MANKIND AND ITS FUTURE 



i27 



Table 11. 



Change in Human Head Form. 



After Krogman, W. M. : The Science of Man in the World Crisis, 



Columbia Univ. Press. 1946. 



generations of man must be solely one moment as compared with the 

 awfully long history of organic evolution. 



Mankind seems to have begun to make a dash at the fate of 

 extermination with a dreadful speed like many other animals that 

 have already become extinct because of rapidly developing orthogenesis. 



3. The Cause of the Orthogenesis of Man 



What is the cause of this dreadful orthogenetic change of man ? 

 Since any gain in height seems neither to have occurred nor to be 

 occvirring in tropical countries or in polar regions such as Greenland 

 and Alaska, where tuberculosis is still increasing far from showing 

 any decline, the main cause of the change must be attributed to 

 climate. It was believed that a gradual lowering of temperature 

 was the primary factor for the gain in height (107), but the writer 

 claims that what has changed and is now changing is the character 

 of genes of mankind rather than climate. 



It may be reasonable to consider that the genes of man have 

 changed by some causes so as to be rendered sensitive to climatic 

 factor and that still at present are being rendered more sensitive to 

 the factor, that is, the genes are changing to lose the rigidity or the 

 elasticity in their structure. 



Many causes are considered by which genes may lose the rigidity, 

 but the most important one may be found in that man becomes 

 well nourished with the advancement of civilization. The writer 

 believes that the effect of deficiency in food counteracts the stimulating 

 action of climate on hypophysis. There are many evidences that 

 inanition injures the pituitary function. Chronically underfed rats 



