NATURE CROWNED IN MAN 553 



us is a succession tax on our inheritance, a lien that the past 

 dwelling in us exacts. It has been a heartening encourage- 

 ment to know that it is an ascent, not a descent, that we 

 have behind us, and that if we read the story aright the 

 Cosmos is rather with us than against us. The recognition 

 of our solidarity with the realm of organisms has been of 

 great importance, and we cannot go back on it. Yet it 

 has perhaps blurred our appreciation of Man's apartness. 



What, then, are the differentiating characteristics of Man 

 that mark him as a being unique and apart? The bipedal 

 uprightness may have had something to do with human 

 speech, and there is undoubtedly interest in various structu- 

 ral peculiarities from chin to heel (taking both these words 

 with anatomical literalness), and from teeth to great toe, 

 but there is little that we can regard as decisive save the 

 size and complexity of the brain, of the cerebral cortex in 

 particular. No normal human subject has less than twice 

 the cranial capacity of say the orang or chimpanzee; the 

 average human brain weighs far more than twice the heaviest 

 gorilla brain. The closely convoluted cerebral cortex, about 

 a foot and a half square if folded out, is composed of some 

 9,000 millions of cells, and is the protoplasmic side of Man's 

 capacity for forming general ideas and experimenting with 

 them (in what we call reason), his power of rational dis- 

 course or language, his vivid self-consciousness of him- 

 self as a personality with a history behind him, and with 

 strong kin-instincts binding him for his own self-realisation 

 to his fellows. 



We lose what Darwin has gained for us if we fail to 

 recognise that many animals seem to have a power of per- 

 ceptual (though probably not of conceptual) inference; that 

 many animals have words though they do not make sentences 



