28 UNIVERSITY OF COLORADO STUDIES 



The question, Will the period of human infancy continue to lengthen ? 

 is an interesting as well as important one. The answer will also imply 

 whether the size of the cerebral cortex will continue to increase, and 

 whether the capacity for intelligence in the human race will continue to 

 increase; and for this reason the solution is a doubly important and 

 interesting one. If the conclusion reached from present indications is a 

 sound one, the answer is not very encouraging, because it is in each case 

 negative. In an article printed in the last issue of these Studies the 

 author has attempted to show that man has about reached his physical 

 and mental limit in evolution. Physical selection became more and 

 more hampered as man became more and more intelligent, and ceased 

 altogether when man gained complete control over nature. Mental 

 selection developed for a long time the size of the brain cortex ; but this, 

 too, if it is changing at all — which is doubtful — is not changing rapidly 

 enough to account for man's progress. In proportion as education 

 becomes a general factor in the human race, cerebral selection also 

 becomes less and less potent, and, where there is universal education, 

 ceases entirely. 



Present conditions maintain the unfit as well as the fit, both physi- 

 cally and mentally. Physical adaptation is by means of surgery and 

 inoculation, and mental adaptation by means of education. The 

 mediocre and even the mentally poor are, by means of education, 

 adapted to their environment, and thus are enabled, like a normal 

 individual, to marry and to bring up a family. The birth-rate among the 

 lower classes is very great, and their natural increase is considerably 

 greater than that of the upper classes. The lower races have smaller 

 and less deeply folded brains than the higher. They also have shorter 

 infancy. A Maori and even a Negro child matures younger than a 

 white one. The Negro adolescent becomes sluggish and mentally inert. 

 This is the age when the child of the white man becomes most active 

 and pliable. There is also somewhat of a general difference between 

 the children of the two classes (upper and lower) at this age. If it is 

 true that the natural increase of the lower races and classes is greater 

 than that of the higher, then the size of the cerebral cortex will tend to 

 diminish, and also the length of the period of teachableness will decrease. 



