REGRESSION 91 



The development has thereby been straightened, shortened, 

 and simplified ; and the evolution of new characters, useful 

 in the new environment, has become possible. Thus, for 

 instance, have been rendered possible the higher characters 

 of man; for even after birth he is closely protected, and 

 therefore, even in that portion of the development which 

 intervenes between the infant and the adult there has been 

 regression. Consider how feeble and helpless the infant is 

 after birth ; but its prototypes of the life-history fought each 

 for its own existence. The infant can digest scarcely anything 

 but milk, and its jaws are very feeble. Its prototypes must 

 have had different and wider powers of assimilation. Perhaps 

 more remarkable than anything is the regression of instinct 

 in man. We shall have to deal with this when we consider 

 Mind, but reflect, meanwhile, how extremely incapable, as 

 compared with young insects for instance, the infant at birth 

 is of adapting itself of its own initiative to the environment. 

 Later, it acquires all kinds of knowledge and ways of thinking 

 and acting, which serve as a superior substitute for instinct. 

 But meanwhile the mother's protection, which renders 

 possible the acquirement, renders useless the instincts of 

 its prototypes, which, therefore, have lapsed. Hence the 

 regression of instinct in man. By it his mental development is 

 shortened and simplified, just as by the regression of bodily 

 parts his physical development is shortened. 1 



155. Biologists at any rate many biologists have fully 

 recognized that development is a recapitulation of the life- 

 history. They have noted the constant tendency towards 

 reversion. They have observed the gradual disappearance of 

 useless organs. They have realized that useless variations, 

 if transmitted, must ultimately render a race incapable of 

 existence. They have recognized that bi-parental repro- 

 duction must have some very highly important function. All 

 these things they have noted, and many of them have 

 declared rightly that Natural Selection, as ordinarily under- 

 stood, is by itself totally inadequate to explain all the 



1 In the foregoing mention has constantly been made of characters 

 lapsed in orderly succession, the last first, the earlier later. But, as 

 already indicated (e.g. among the medusae), earlier characters may 

 sometimes lapse before the later. This may happen especially when 

 some parts of the life-history are not direct, but form, so to speak, a loop 

 for example, when evolution, and consequently development, have 

 been rendered indirect by the action of reversed selection. The omis- 

 sion of the loop would straighten and therefore shorten the development. 

 Considering how condensed the development is, it is probable that this 

 has occurred not infrequently. 



