We should, however, be cautious before accepting this estimate of 

 population range. There seems to be little doubt that between the 

 australopithecine and habiline stages on the one hand, and the H. sapiens 

 stage on the other hand, the mean cranial capacity of mankind doubled 

 its size— from the 450 c.c. and 650 ex. of the earlier stages to the 1300 

 c.c. and more of the sapient stage. The process of doubling the brain size 

 is what characterized that stage of mankind usually lumped into the 

 taxon Homo erect us. It is clear that selection must have been operating 

 most vigorously in favor of larger brains during the emergence and life- 

 span of the species Homo erectus. One might expect, therefore, that 

 some populations of H. erectus would be characterized by appreciably 

 larger brains and others by appreciably smaller brains than the species 

 average. Two such populations may be represented by the Indonesian 

 group (often recognized as the subspecies H. erectus erectus), with a 

 sample mean capacity of 859 c.c, and by the Choukoutien group (H. 

 erectus pekinensis), with a sample mean of 1043 c.c. In relation to such 

 subspecific groups, the position of the isolated specimens from Lantian 

 and Olduvai must, for the time being, remain in suspense. 



Under these conditions of a dramatic selection for larger brain size, 

 with consequent diversification of populations with respect to this param- 

 eter, it may well be inquired whether it is biologically meaningful to 

 compute a species average for the parameter in question and, by the 

 pooling of data from such disparate populations, to attempt to assess 

 the species standard deviation and population range. Statistically impec- 

 cable though the procedure might be. it may seriously be questioned 

 whether normal statistical procedures can be invoked here under condi- 

 tions of rapid evolution and changing patterns of brain size. The very 

 meaningfulness of the biological events occurring at this critical stage 

 of hominization may be masked by the statistical pooling of all the data 

 from the geographically, chronologically, and evolutionarily dispersed 

 populations. 



Note to chapter five 



Professor Georges Olivier, head of the Laboratoire d' Anthropologic 

 biologique in Paris, has used a somewhat different approach to estimate the 

 standard deviations and population limits of hominoids (1971, personal com- 

 munication). He based his estimate on Sacchetti's (1942) demonstration that 



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