72 The Recapitulation Theory and Human Infancy 



often have life-saving value as such, and would therefore in the 

 long run preserve and select individuals in whom the fixed and 

 physically inherited germinal variations should increase in the 

 direction of better adaptations. Plasticity and its habits would 

 thus blaze the way along which germinal evolution could follow, 

 because the incidence of natural selection would fall first upon 

 habits and only through them upon the physical make-up of the 

 animal. With the rise of tradition the value of this process 

 would increase, so that on higher simian levels and early human 

 levels the selection of hereditary strains was increasingly deter- 

 mined by the character of the social habits directly or indirectly 

 favoring survival and leaving of offspring. Infancy being es- 

 pecially responsible for the assumption of habits, in this manner 

 becomes intimately related to organic evolution to the extent 

 that the theory of organic selection is true. 



In the light of these later contributions, Fiske's original state- 

 ment of the theory of infancy requires some amplifying. The 

 biological explanation of infancy assumes that with this period 

 is associated species preservation and success, and in the case of 

 man, species dominance. The advantages accruing to species 

 because of infancy reside in the greater adaptability of individu- 

 ally acquired habits over the mechanical behavior of instinct. 

 This is made possible by an elaboration of the central nervous 

 system, especially in the cerebral portions. But the accumula- 

 tion of habits requires time and practice and a degree of ineffi- 

 ciency and dependence corresponding to the difference at any 

 time obtaining between the neuro-muscular condition of the 

 young and that of the adult. Among the higher primates these 

 habits are in large part socially derived, calling for the psycho- 

 physical adjustments of suggestion and imitation on the part of 

 infancy to insure their transmission. The inefficiency of infancy 

 necessitates counterbalancing parental oversight, and the indis- 

 pensable practice is obtained by imposing upon the young an 

 instinctive need of self-exercise or play. This spontaneous 

 exercise is directed not only upon well-defined tendencies char- 

 acteristic of the adult life of the species in need of perfecting, but 

 also to modes of social action resting slightly upon an instinctive 

 basis and more largely acquired by successive generations in re- 

 sponse to the changing conditions of their lives. Play is there- 

 fore both specific in its forms and broadly imitative and general- 



