122 THE RELATIONS OF MAN 



tematic value, for the simple reason that, as may be conclud- 

 ed from what has been already said respecting cranial ca- 

 pacity, the difference in weight of brain between the highest 

 and the lowest men is far greater, both relatively and abso- 

 lutely, than that between the lowest man and the highest 

 ape. The latter, as has been seen, is represented by, say 



ally, and with much seeming plausibility, argue that the vast intellectual chasm 

 between the Ape and Man implies »a corresponding structural chasm in the 

 organs of the intellectual functions ; so that, it is said, the non-discovery of 

 such vast diflferences proves, not that they are absent, but that Science is in- 

 competent to detect them. A very little consideration, however, will, I think, 

 show the fallacy of this reasoning. Its validity hangs upon the assumption, 

 that intellectual power depends altogether on the brain — whereas the brain is 

 only one condition out of many on which intellectual manifestations depend ; 

 the others being, chiefly, the organs of the senses and the motor apparatuses, 

 especially those which are concerned in prehension and in the production of 

 articulate speech. 



A man born dumb, notwithstanding his great cerebral mass and his inherit- 

 ance of strong intellectual instincts, would be capable of few higher intellec- 

 tual manifestations than an Orang or a Chimpanzee, if he were confined to the 

 society of dumb associates. And yet there might not be the slightest discerni- 

 ble difference between his brain and that of a highly intelligent and cultivated 

 person. The dumbness might be the result of a defective structure .of the 

 mouth, or of the tongue, or a mere defective innervation of these parts ; or it 

 might result from congenital deafness, caused by some minute defect of the 

 internal ear, which only a careful anatomist could discover. 



The argument, that because there is an immense difference between a Man's 

 intelligence and an Ape's, therefore, there must be an equally immense differ- 

 ence between their brains, appears to me to be about as well based as the 

 reasoning by which one should endeavour to prove that, because there is a 

 " great gulf" between a watch that keeps accurate time and another that will 

 not go at all, there is therefore a great structural hiatus between the two 

 watches. A hair in the balance-wheel, a little rust on a pinion, a bend in a 

 tooth of the escapement, a something so slight that only the practised eye of 

 the watchmaker can discover it, may be the source of all the difference. 



And believing, as I do, with Cuvier, that the possession of articulate speech 

 is the grand distinctive character of man (whether it be absolutely peculiar to 

 him or not), I find it very easy to comprehend, that some equally inconspi- 

 cuous structural difference may have been the primary cause of the immeasu- 

 rable and practically infinite divergence of the Human from the Simian Stirps. 



