1 3 o THE EVOLUTION OF MAN 



be believed by some of his readers that he is not endeavoring 



to do it. 



But the analogy, correctly understood and not burdened 

 with a weight it cannot carry, can perform a service of great 

 value. If in one field of investigation (say the organic) we 

 know that certain phenomena are produced in a certain way, 

 and if in an adjacent, less understood field (say the social) we 

 find analogous phenomena, we are justified by long experience 

 in the inference that the unknown producing factors in the new 

 field are probably similar to the known ones in the older range. 

 If, in particular, we find adjustments in the organic field pro- 

 duced by the so-called Darwinian factors, and if we discover 

 that the social range shows social forms representing adjust- 

 ments to the life-conditions of society, it is reasonable to infer 

 that the factors producing social adjustments may be similar 

 to those producing organic adjustments. This is the more 

 likely in view of the fact that all members of human society 

 are organisms, so that the two ranges of organic and of 

 social life are not merely contiguous, but interpenetrative. 

 If organic forms are evolved by the action of the Darwinian 

 factors of variation, selection, and heredity, their joint action 

 resulting in adjustment to life-conditions, it is a hint to us that, 

 in default of any more promising lead, we had better look for 

 counterparts of the Darwinian factors in the social range. 



This suggestion has been unreflectingly and unconsciously 

 adopted in popular usage. It is seen that habits and customs 

 are passed on from generation to generation somewhat as 

 bodily qualities are. It is necessary to use some term to cover 

 the process. The biological term is heredity. It is easier to 

 catch up a term in use than to invent a new one. Hence 

 writers speak of "social heredity." It is like speaking of 

 "brass andirons." However, it is vaguely realized that habit 

 and custom are not transferred by actual heredity, through the 

 germ-plasm; and the perception of the unanalyzed difference 



