pointed out, "It makes little sense to compare . . . [coefficients of varia- 

 tion] and . . . [standard deviations] for large samples (n > too) with those 

 based on very small samples, for example, chimpanzee and gorilla with 

 australopithecines . . ." (Holloway 1966a, p. 1108). 



We conclude that we simply do not have enough information from 

 which to infer whether the variation of cranial capacity in Australopithecus 

 was closest to that in chimpanzee, orangutan, gorilla, or modern man. To 

 base deductions on gorilla and modern man only would seem to imply that 

 the cranial capacity of A. africanus was of a comparable high order of vari- 

 ability to those of man and gorilla, and similarly showed occasional very 

 high values. Yet modern man is highly polytypic as well as polymorphic, a 

 factor that undoubtedly accounts for much of the high (interracial) variance 

 of many metrical traits of modern man, including cranial capacity. We have 

 no evidence that A. africanus was polytypic to a similar degree. Hence, we 

 cannot assume that a comparable degree of variation applied to this extinct 

 group. 



The skewness of the available samples of 

 hominoid cranial capacities 



Much has been made of the maximum cranial capacity of the gorilla 

 (752 c.c). Yet, it is important that this solitary reading be viewed in proper 

 perspective. Such a value has occurred only once in 668 gorilla crania for 

 which the capacities are on record. The second largest gorilla capacity on 

 record is as much as 67 c.c. smaller! The value of 752 c.c. exceeds the gorilla 

 combined male and female mean of 504.6 by 3.75 S.D.s. The second highest 

 gorilla capacity (685 c.c.) is only 2.74 S.D.s above the combined-sex mean. 

 From what has been said above, it would be more realistic to compare the 

 value of 752 c.c, which came from a male animal, with the mean (534.6 

 c.c.) for the total pooled male series (n = 414): 752 c.c. is 3.81 S.D.s above 

 this mean, whilst the second largest cranial capacity (685 c.c.) is 2.64 S.D.s 

 above the male mean. 



At the other extreme, the smallest recorded adult gorilla capacity (340 

 c.c.) is 2.50 S.D.s below the combined-sex mean and 2.56 S.D.s below the 

 total pooled female mean. The lowest capacity recorded for an adult male 

 gorilla (412 c.c.) is 2.15 S.D.s below the total pooled male mean. 



Hence, the distribution of gorilla capacities was nearly symmetrical 

 until Schultz (1962) discovered the gorilla cranium with 752 c.c. Clearly, 

 this single gorilla cranium has positively skewed the distribution curve. 



49 K 



