VIII 



GROWTH AND EVOLUTION 



249 



Bolk's somewhat exaggerated formulation this is a "fetalization", that is, a 

 neoteny-Hke retardation of development and sexual maturation providing man 

 with his long period of youth, the capability of learning and, owing to the 

 necessity of a long period of parental care for the children, with an essential basis 

 for formation of social units. 



Fig. 48. Comparison of the development of the chimpanzee [A-D) and man (E-F). 

 A foetus, B 9, 74 days old, C young animal, D young 9 chimpanzee. E human foetus gth 

 month, F adult. The transformation shows that the aduh human skull does not correspond 

 to a developmental stage of the chimpanzee, but ontogenesis in man has taken a course 

 different from that in the chimpanzee. After Kummer, 1953. 



It is a well-known fact that the cranium of, e.g., the baby chimpanzee is much more 

 "human" than that of the adult. Hence human development can be envisaged as a growth 

 problem in a second aspect, namely, to what extent human morphology can be considered 

 a continuation of that of anthropoids. Kummer (1953) studied this problem by the method 

 of coordinate transformation. The conclusion is that ontogenetic development of the human 

 skull is not a mere continuation of, but marks a deviation from that in the chimpanzee 

 (Fig. 48). Another inference which can be drawn from coordinate transformation and 



Literatnre p. 253 



