THE EVOLUTION OF INTELLIGENCE 107 



species, and the same thing is true of the reflexes and, pre- 

 sumably, of the tropisms. 



Among the various theories of the origin of this group of 

 instinctive and reflex actions, two have been most frequently 

 urged. The one derives its chief support from an examination 

 of the supposed facts in the case of human beings. It assumes 

 that the expression of life in its original forms was sponta- 

 neous and indefinitely variable. It further assumes that some- 

 thing comparable with volition is present in these primitive 

 spontaneous expressions and that this volition is intrinsically 

 intelligent, so that among the various spontaneous, or random, 

 forms of movement which may be indulged there is presently 

 a selection of those which are most useful and a suppression or 

 elimination of those which are harmful. Whereupon it is 

 further assumed that these beneficial spontaneous reactions 

 become embedded as fixed habits which presently are trans- 

 mitted by heredity to succeeding generations. They constitute 

 on this theory a sort of frozen intelligence. Although this 

 view has been held in times past by scientific men of eminence, 

 it is certainly not looked upon with favor by any considerable 

 number of contemporary scientists. It makes assumptions 

 about inheritance which are almost certainly incorrect and 

 assumptions about primitive intelligence which are highly im- 

 probable. Over against it is the view that, behavior being 

 essentially a function of structure, reflexes, instincts, and 

 tropisms simply represent accidental variations which have sur- 

 vived, just as the variations of form have survived, because 

 they were, on the one hand, positively useful, or, on the other 

 hand, sufficiently harmless to permit their continuation, if only 

 they chanced to be combined with other reactions of a pre- 

 servative kind. Both theories admit that, as things now 

 stand, acts of reflex and instinctive character, whatever their 

 evolutionary history, are as such intrinsically non-intelligent, 



