54.5 % 



t 



■7 



289 c.c. 530 c.c. 



Figure 18: The biparietal partial endocast and the total endocast of Olduvai 

 hominid 5 (type specimen of Australopithecus boisei). 



based on Dubois's figure of 935 c.c, came to 50.22 per cent. Since then, I 

 have had the opportunity of reestimating the total volume of the Trinil 

 specimen (see chapter on Homo erectus, p. 81): it amounts to 854 c.c, 

 and so the new percentage for Trinil is 55.02 (Tobias 1967a, 1968b). This 

 new result yields a ratio of biparietal to total endocast volume that ranges 

 from 54.45 per cent to 56.54 per cent. 



When the original list of percentages was applied to H. habilis, 

 estimates were obtained that ranged from 642.7 to 723.6 c.c, with central 

 values of 673.5 an d 680.8 c.c (Tobias 1964). 



When the revised list of percentages, modified by the new value for 

 Trinil, is applied to H. habilis, somewhat lower values are obtained: the 

 range of estimates now becomes 642.7 to 667.4 c.c (Figure 17), with a 

 central value of 657 c.c instead of the former estimate of 675 to 680 c.c 

 (Tobias 1968b, p. 83). 



The new revised estimate of 657 c.c. for the type specimen of H. habilis 

 exceeds my new estimate of the A. africanus mean of 494 c.c. by 163 c.c, 

 or 3.93 S.D.s. This value is extremely high and confirms that the estimated 

 cranial capacity of the type specimen of H. habilis is significantly greater 

 than the mean capacity of the available sample of A. africanus capacities. 



If we compare the value of 657 c.c. with Robinson's proposed new 

 mean for A. africanus, namely 430 c.c, the excess is 277 c.c or 5.47 S.D.s 

 (by my estimate, i.e., S.D. = 41.5 c.c) or 4.54 S.D.s (by Robinson's 



67 & 



