Exactly the same results were obtained by Spann and Dustmann (19(15) 

 in a study of 1229 male and 632 female brains in the medicolegal institute 

 at the University of Munich: brain weight rose with increasing stature, but 

 no association could be determined between brain weight and body weight. 

 In 19(1(1, Schreider reanalyzed some old brain and body measurements made 

 in Paris in 1865-1870 by Paul Hroca, one of the great anatomists of the 

 last century. Schreider found that between brain weight and body height 

 there was a positive correlation coefficient of 0.26 for 224 males and o.'ji for 

 1 1 1 females. 



Clearly, if one does not allow for the varying average body sizes of dif- 

 ferent populations, one may be misled into making false statements about 

 the existence of real differences in average brain size among the popula- 

 tions compared. Thus, in the Raymond Hoffenberg Lecture of 1969 I 

 showed that as yet no single study on the supposed differences between the 

 mean brain weight of Negroes and of Caucasoids is valid because, among a 

 number of other reasons, none of them has expressed or taken into account 

 the height or stature measurements of the populations from which the 

 brains were drawn (Tobias 1970). In my study I attempted an analysis in 

 which stature was considered. This produced results suggesting that the dif- 

 ferences among various racial or population groups are negligible, once 

 allowance has been made for body size. 



The studies on brain-body size ratio have spawned one interesting line 

 of thinking that attempts to bridge the gap between brain size and neuronal 

 contents. This we shall discuss now. 



Brain size and neurons 



In comparisons among different animals, K. S. Lashley (who gave the 

 James Arthur Lecture in 1945) suggested that the total amount of brain 

 material, expressed as a fraction of total body size, "seems to represent the 

 amount of brain tissue in excess of that required for transmitting impulses 

 to and from the integrative centres" (Lashley 1949, p. 33). Following up 

 this notion, Jerison (1963) has demonstrated that brain size may be con- 

 sidered as 2 separate components: the first is directly related to the size of 

 the body, and it is bigger in Primates with bigger body size, and vice versa. 

 The other component seems to vary independently of body size; it com- 

 prises the "surplus" nerve cells that are present over and above those re- 

 quired for the satisfaction of immediate bodily needs. These "surplus" 

 nerve cells, Jerison suggests, are available for response to the challenge of 



& 108 



