44 Heredity and Social Progress 



disaster checks progress and leaves a heritage 

 of emotional products that are seldom removed. 

 Facts of this kind are plain enough when 

 human society is under observation. No one 

 would expect an epidemic of small-pox or of 

 cholera to raise the intellectual level of a 

 nation, nor do people seek for famines or social 

 disorder to elevate mankind. The same injury 

 of the living would be observed if the effects of 

 the destruction caused by beasts of prey could 

 be accurately ascertained. In the case of ani- 

 mals we see, not the immediate effect of the 

 first onslaughts, but the slowly wrought adjust- 

 ment between the weak and the strong. The 

 victims have changed environments many times 

 to avoid death, and the readjustments between 

 their changed organs and their new habitats 

 have often proved advantageous. There may, 

 therefore, be an improvement in the long run, 

 and yet the emotion which arrested develop- 

 ment and impelled each change may have been 

 injurious if judged from the standpoint of the 

 present. There would in each case be a dwarf- 

 ing and a changed relation of parts, and then a 

 growth with these proportions, if the shifting 



