estimate: namely to 600 c.c. This figure was an increase of 20 per cent and 

 was based on Keith's own study of the growth of cranial capacity in gorillas 

 (Keith 1931, p. 65). 



The figure of 600 c.c. was accepted too by Le Gros Clark (1964), al- 

 though he had earlier (1947) used Zuckerman's (1928) data on chimpanzees 

 to estimate an adult size of about 570 c.c. (or rather more, if Dart's estimate 

 of 520 c.c. for the child were accepted as the basis). 



In 1958 Ashton and Spence published a new important contribution on 

 the cranial capacity at various ages in several living species of the Hominoi- 

 dea. They found that by the time the first molar has erupted endocranial 

 capacity has reached 94 per cent of adult size in man and chimpanzee, 91 to 

 92 per cent in orangutan, and 90 per cent in gorilla. Thus, for this group 

 of hominoids the mean values fluctuate narrowly between 90 and 94 per 

 cent. The unweighted mean percentage for the 4 kinds of living hominoids 

 is 92.5. 



On the basis of this intergroup mean of 92.5 per cent I recomputed the 

 "adult value" for Taung as 562 c.c. (Tobias 1965a). For this estimation I 

 employed the juvenile value of 520 c.c. based on Dart (1926) and Schepers 

 (1946, Table 1). I now feel that it would be safer to accept the juvenile value 

 of no more than 500 c.c, as found by Zuckerman (1928) and Schepers (1946, 

 p. 238, in text). On the basis of this figure of 500 c.c. and the correction 

 factor of 92.5 per cent derived from Ashton and Spence (1958), one arrives at 

 the adult value for Taung of 540 c.c* This happens to be exactly the same 

 figure that Zuckerman had arrived at on the basis of his chimpanzee data in 

 1928, when sex differences were not taken into account. 



The figure of 540 c.c. is therefore tentatively accepted by me as the 

 nearest approach we can make with present information, and with the 

 reconstructions of Dart and Schepers, to the adult endocranial capacity of 

 the Taung creature. The figure should now replace such previous estimates 

 in the literature as 562, 570, and 625 c.c. It should be stressed that I have 

 made no new reconstruction of the endocast but have based my computa- 

 tions on Dart's original reconstruction— which was acceptable to Zuckerman, 

 Schepers, and Le Gros Clark. Needless to say, other reconstructions are 

 possible, which would yield varying estimates of the child's total cranial 

 capacity and, hence, of the adult value. Holloway's new reconstruction is 

 an example. 



* Holloway (1970b) used the figure of 92.0 per cent to compute an adult estimate of 440 c.c. from 

 the capacity of his new reconstruction (405 c.c). 



15 u 



