1 16 THE ASCENT OF MAN 



That Evolution should leave such clues lying about 

 is at least an instance of its candour. 



But this does not exhaust the betrayals of this 

 most confiding organ. If we turn from the out- 

 ward ear to the muscular apparatus for working 

 it, fresh traces of its animal career are brought to 

 light. The erection of the ear, in order to catch 

 sound better, is a power possessed by almost all 

 mammals, and the attached muscles are large and 

 greatly developed in all but domesticated forms. 

 This same apparatus, though he makes no use of 

 it whatever, is still attached to the ears of Man. 

 It is so long since he relied on the warnings of 

 hearing, that by a well-known law, the muscles 

 have fallen into disuse and atrophied. In many 

 cases, however, the power of twitching the ear is 

 not wholly lost, and every school-boy can point to 

 some one in his class who retains the capacity, 

 and is apt to revive it in irrelevant circumstances. 



One might run over all the other organs of the 

 human body and show their affinities with animal 

 structures and an animal past. The twitching of 

 the ear, for instance, suggests another obsolete, or 

 obsolescent power — the power, or rather the set of 

 powers, for twitching the skin, especially the skin 

 of the scalp and forehead by which we raise the 

 eyebrows. Subcutaneous muscles for shaking off 



