PHYSICAL AND MENTAL TRAITS 445 



would not, speaking generally, be useful. Thus, under a dominant 

 church, clear, far-reaching, fearless love of truth conduced more 

 often to death by torture than to survival during the dark ages of 

 Europe. Even now they are apt to handicap the individual in 

 many walks of life ; though under our more complex and en- 

 lighted conditions a greater diversity of mental type is both possible 

 and beneficial to him. 



729. From the point of view of the social reformer the impor- 

 tant fact is that man's intellectual powers, including his capacity to 

 learn even in old age and to communciate his acquired knowledge, 

 thoughts, and mental attitudes to his fellows, confer on him great 

 powers of altering the mental and material environment and of 

 adapting himself, and more especially the next generation, to the 

 alteration. Improved mental development may thus be made, if 

 not positively beneficial to the individual in his struggle for 

 existence, at least not positively injurious. For example, in the 

 course of one or more generations a savage environment may be 

 exchanged for one more civilized ; or an atmosphere of prejudice 

 and superstition may be made to yield to one relatively more 

 enlightened. Modern Japan, in which ideas are now openly 

 prevalent the expression of which only a few years ago would have 

 entailed death, is a case in point. Though the mind of this race 

 has altered in some very important particulars, though it has 

 some intellectual characters different from those which it lately 

 possessed, yet we have no reason to suspect any germinal altera- 

 tion such as would probably be indicated by a marked change in 

 physical growth. 



730. To sum up : racial capacities for physical and mental 

 development cannot be altered except by selection, or lack of 

 selection, or in rarer instances (as in the case of European breeds 

 of dogs in India) through injury to the germ-plasm. Speaking 

 practically, physical and mental characters which develop under 

 the stimulus of nutriment cannot be improved in the mass of the 

 population except through selection. Physical characters which 

 develop under the stimulus of use may be considerably improved 

 without selection in many sections of the community ; but each 

 improvement, however beneficial, can consist only in mere 

 extensions of growth previously made under the stimulus of 

 nutriment. On the other hand, it is probable that the mental 

 characters which develop under the stimulus of experience may be 

 immensely improved in many directions in all sections of the 

 community by careful training and without resort to selection. 



