458 DARWINISM chap. 



less than 31 or 32 ounces, or that the heaviest gorilla 

 brain has exceeded 20 ounces," although " a full-grown 

 gorilla is probably pretty nearly twice as heavy as a Bosjes 

 man, or as many an European woman." ^ The average 

 human brain, however, weighs 48 or 49 ounces, and if we take 

 the average ape brain at only 2 ounces less than the very 

 largest gorilla's brain, or 18 ounces, we shall see better the 

 enormous increase which has taken place in the brain of man 

 since the time when he branched off from the apes ; and this 

 increase will be still greater if we consider that the brains of 

 apes, like those of all other mammals, have also increased 

 from earlier to later geological times. 



If these various considerations are taken into account, we 

 must conclude that the essential features of man's structure 

 as compared with that of apes — his erect posture and free 

 hands — were accjuired at a comparatively early period, and 

 were, in fact, the characteristics which gave him his superiority 

 over other mammals, and started him on the line of develop- 

 ment which has led to his conquest of the world. But during 

 this long and steady development of brain and intellect, man- 

 kind must have continuously increased in numbers and in 

 the area which they occupied — they must have formed what 

 Darwin terms a " dominant race." For had they been few^ in 

 numbers and confined to a limited area, they could hardly 

 have successfully struggled against the numerous fierce 

 carnivora of that period, and against those adverse influences 

 which led to the extinction of so many more powerful 

 animals. A large population spread over an extensive area 

 is also needed to supply an adequate number of brain varia- 

 tions for man's progressive improvement. But this large 

 population and long-continued development in a single line 

 of advance renders it the more difficult to account for 

 the complete absence of human or pre-human remains in 

 all those deposits which have furnished, in such rich 

 abundance, the remains of other land animals. It is true 

 that the remains of apes are also very rare, and we may 

 well suppose that the superior intelligence of man led him to 

 avoid that extensive destruction by flood or in morass w^hich 

 seems to have often overwhelmed other animals. Yet, w^hen 

 ^ Man 8 Place in Nature, p. 102. 



