THE FUTURE EVOLUTION OF MAN 265 



man species, in its development, has lost a large por- 

 tion of its instincts, and has gained, instead, the 

 power of intelligent choice and the ability to learn 

 by imitation. When these drop away, man without 

 his instincts or his intelligence is more helpless than 

 the brute. Students of sociology are making clear 

 to us that a large portion of the criminality of the 

 world, much of the looseness of life, and a large 

 part of the alcoholic excesses are due to this taint of 

 feeble-mindedness. Recent investigations have made 

 it clear that one feeble-minded family in a commu- 

 nity may, in the course of years, poison the life of 

 an entire state. The Jukes family in New York, the 

 Kallikak family in New Jersey, have shown the 

 awful possibilities of descent from a single feeble- 

 minded ancestor. Prisons, almshouses, and houses 

 of shame owe their population in no small degree to 

 this bitter curse. It will not be long before society 

 will learn to protect itself against such poisoning of 

 the human stock. Nothing is more clear to the in- 

 vestigator of this subject than that the one over- 

 whelming cause for feeble-mindedness is feeble- 

 mindedness in the parentage. 



There is one type of mental weakling, known as 

 the Mongolian idiot, which may arise right out of 

 the heart of an apparently sound family. But the 

 number of these is comparatively small. The num- 



