conditions, and swells under yet other circumstances, though the braincase 

 itself has not been shown to diminish in capacity (Anderson 1910; Stillman 

 1911; Zuckerman 1928; Appel and Appel 1942; Tobias 1970). Hence, as the 

 quality and duration of life change, the non-neural endocranial capacity 

 increases, and one's head becomes rilled more and more with fluid and 

 meninges (Anderson 1910; Stillman 1911; Todd 1923; Greenfield and 

 Carmichael 1925; Zuckerman 1928). 



We know a little of the percentage of the cavity occupied by non- 

 neural contents at different ages (Donaldson 1895, Bolk 1904, Rudolph 

 1914, cited by Zuckerman 1928). What correction should we apply, for 

 example, to the cranial capacity of the Taung child who had just reached 

 the stage of erupting his first permanent molar tooth, that is, an age of 

 perhaps five or six years? And what correction to Sterkfontein 5 who was 

 old enough for the sutures of her cranium largely to have closed? How much 

 for the capacity of Olduvai hominid 5 (A. boisei, formerly called Zinj- 

 anthropus), who died as an adolescent with incompletely erupted wisdom 

 teeth (third molars)? We can arrive at only approximate answers to these 

 questions on the age variations in the ratio of brain size to cranial capacity. 



Some lead is given by a table published in Tabulae Biologicae, 1941. 

 For a series of ages from birth to twenty years, the table cites the volume of 

 the brain, the cranial capacity, and the weight of the brain. The figures in 

 our Table 1 are extracted from this source. The capacity of the cranium in 

 the newborn infant is cited as 1.01 to 1.06 times as great as the volume of 



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