21 6 ADAPTATION AND PROGRESS 



brain. The plastic period of adolescence, lengthened in civilized 

 man until it has come to cover more than one-third of his life- 

 time, is thus the guaranty of his boundless progressiveness. . . .* 

 In its crude beginnings the psychical life was but an appendage 

 to the body, in fully- developed humanity the body is but the 

 vehicle for the soul." 2 



Fiske goes on to show the necessity of prolongation of infancy 

 with the development of higher forms of animal life, in order that 

 the organism may adjust itself to the ever increasing complexity 

 of its environment. In lower forms the reactions are automatic 

 or instinctive, but such are not sufficient for higher forms which 

 must learn by experience, and a prolonged infancy affords a 

 period of training so that when independent life is entered upon 

 the organism will have a fair chance of survival. " While the 

 nervous connections accompanying a simple intelligence are 

 already organized at birth," he says, " the nervous connections 

 accompanying a complex intelligence are chiefly organized after 

 birth. . . . Infancy, psychologically considered, is the period 

 during which the nerve connections and correlative ideal associa- 

 tions necessary for self-maintenance are becoming permanently 

 established. Now this period, which only begins to exist when 

 the intelligence is considerably complex, becomes longer and 

 longer as the intelligence increases in complexity. In the human 

 race it is much longer than in any other race of mammals, and it is 

 much longer in the civilized man than in the savage." 3 



According to our author this prolongation of infancy had a 

 profound sociological effect in uniting the parents in a more 

 permanent family life required for the protection of the helpless 

 infant, in this way developing sympathy, the basis of sociality. 

 " Thus we cross the chasm which divides animality from human- 

 ity, gregariousness from sociality, hedonism from morality, the 

 sense of pleasure and pain from the sense of right and wrong." 4 

 The prolongation of infancy is of vital importance, then, not only 

 in the development of the nervous system and its acquirement of 

 modes of activity making for adaptation, but in the establish- 



1 Destiny of Man, pp. 30, 56. * Cosmic Philosophy, ii, p. 342. 



2 Ibid., p. 65. Ibid., p. 346. 



