years behind that of the normal modern child. When reproductive age was 

 reached, the Pithecanthropus had no more than seven years of cultural experience, 

 whereas when the modern man reaches reproductive maturity he has at least 

 twelve years of cultural experience. Age estimates of known fossil men indicate 

 a very low life expectancy as with modern hunters and gatherers. In this case, five 

 years would be an appreciable portion of the lives of most individuals. 



This shorter period of full cultural participation would limit the total 

 quantity and complexity of cultural content that is likely to be transmitted in 

 each generation. When the age of onset of symbolizing is lowered by increasing 

 the child's brain size, the amount of cultural material that can be transmitted is 

 increased. [Ibid., p. 86] 



This interesting suggestion is put forward to explain the extraordinar- 

 ily slow rate of change in the lower Palaeolithic. At the same time, it is 

 suggested by Krantz that this may explain the large mass of superfluous brain 

 tissue in modern man. The latter implication is predicated upon the assump- 

 tion that the patter?/ of brain growth would not have changed during evolu- 

 tion, at least from H. erectus to H. sapiens. Yet, the pattern does differ ap- 

 preciably between modern pongids and modern hominids (Zuckerman 1928; 

 Keith 1931), the most notable difference being the steep initial postnatal rise 

 in man, as compared with the apes. It is of course possible that there may 

 have been a steady change in the curve of growth from the pongid pattern 

 to the modern human curve during the several stages of hominization. From 

 the nature of the material, however, the major changes are likely to have 

 been at levels from pre- Australopithecus to Australopithecus to H. habilis to 

 H. erectus. It is likely that, as Krantz assumes, the pattern of growth would 

 have attained to something essentially similar to that of modern man by the 

 time of H. erectus. In that event, his hypothesis would seem to be a valuable 

 contribution to our thinking about brain sizes, ancient and modern. 



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There has been much discussion in the literature as to the primacy of 

 structural modifications or of behavioral changes during evolution. Thus, 

 Washburn and Hamburg (1965), Washburn (1967), and Washburn and 

 Shirek (1967) stress that behavior precedes structure in evolution. This in 

 turn leads them to relegate a terminal role to the brain in human evolution. 

 This view has been opposed by Holloway, who argues the converse, namely 

 that the brain had a primary role in human evolution. It is obvious for 

 him that "for any behavioral change to be evolutionary in significance, it 

 must first rest upon an organic basis, underlain by a genetic change asso- 



5sf 142 



