A close look at this ingenious suggestion reveals the basic assumption 

 Krantz has made, namely that because species with bigger brains (on the 

 average) have better memories than other species with smaller brains, within 

 a species individuals with bigger brains would be endowed with better 

 memories than those individuals with smaller brains. I do not know of any 

 experimental evidence to support this assumption at the intra-specific level. 

 In fact, the problem seems analogous with the question of intelligence and 

 brain size: within a species it has not proved possible to demonstrate valid 

 genetic differences in intelligence or achievement between big-brained and 

 small-brained variants (Tobias 1970). Unfortunately, if one questions 

 Krantz's assumption, the edifice of his hypothesis likewise must be called 

 into question. 



All we can say is: (a) we need more information about the memory 

 retention ability of big- and small-brained individuals within a species, and 

 (b) memory may well be one, but only one, of a number of functions that 

 have improved and increased with the development of greater internal struc- 

 tural complexity of the brain, which in turn has gone along with the increase 

 in size of the brain. Selection for better memory may well be one of the 

 selective pressures that favored larger brains during hominization. But there 

 is no reason to believe it to be either the only one or even the main one. 



Krantz himself suggested another mechanism of selection for increase of 

 brain size— only this time not for the jump from Australopithecus to H. 

 erect us but for that from H. erectus to H. sapiens. He was perplexed by the 

 fact that cultural evolution moved so slowly during the "Lower Palaeolithic." 

 How did it come about that a few simple stone implements such as hand 

 axes and chopping tools persisted virtually unchanged for over a hundred 

 thousand years? His hypothesis is based on the growth pattern of the hominid 

 brain. This leads him to suggest that the small-brained Palaeolithic people 

 as adults were as well endowed as their modern descendants, but that as 

 young children they were incapable of the use of symbolic language. "This 

 shortened the time available for acculturation and thus limited the culture 

 content" (Krantz 1961, p. 85). Krantz accepts that "virtual humanity is 

 reached with a normally developed brain in excess of the 750 c.c. threshold." 

 Why then, he asks, do modern human brains average about 1400 c.c? Why 

 is there a further increase in average endocranial capacity of 65 per cent 

 from H. erectus to H. sapiens! There does not seem to be any marked intel- 

 lectual improvement, and we know that among modern people no clear 



% Ho 



