MAN. 603 



More important, however, is the fact that the weight of 

 the gorilla's brain bears to that of the smallest brain of 

 an adult man the ratio of 2 : 3, and to the largest human 

 brain the ratio of i : 3 ; in other words, a man may have 

 a brain three times as heavy as that of a gorilla. The brain 

 of a healthy human adult never weighs less than 31 or 32 

 ounces ; the average human brain weighs 48 or 49 ounces ; 

 the heaviest gorilla brain does not exceed 20 ounces. "The 

 cranial capacity is never less than 55 cubic inches in any 

 normal human subject, while in the Orang and Chimpanzee, 

 it is but 26 and 37^ cubic inches respectively." 



But, as Owen allowed long since, there is an " all-pervad- 

 ing similitude of structure" between man and the anthropoid 

 apes. As far as structure is concerned, there is much less 

 difference between man and the gorilla-than there is between 

 the gorilla and the marmoset. 



The arguments by which Darwin and others have sought 

 to show that man arose from an ancestral type common to 

 him and to the higher apes, are the same as those used to 

 substantiate the general doctrine of descent. The " Descent 

 of Man " is the expansion of a chapter in the " Origin 

 of Species.^' The arguments may ba briefly summarised. 



(i) Physiological. The bodily life of man is like that of 

 monkeys ; both are subject to similar diseases ; various 

 human traits of gesture, expression, etc., are paralleled 

 among the " brutes ; " reversions and monsters corroborate 

 the alliance sadly enough. ' 



(2) Morphological. The structure of man is like that of 

 the anthropoid apes ; none of his distinctions, except that 

 of a heavy brain, are momentous ; there are about eighty 

 vestigial structures in his muscular, skeletal, and other 

 systems. 



(3) Historical. Certainties in regard to remains of pri- 

 mitive man are few, but his individual development reads 

 like a recapitulation of ancestral history. 



To many, man seems too marvellous to have been natur- 

 ally evolved, to others the evidence seems insufiScient, but 

 if the doctrine of descent is true for other organisms, it is 

 likely that it is true for man also. 



As to the antiquity of the human race, it is certain that 

 men lived in Europe in the later stages of the Ice Age, and 



