76 Darwin, and after Darwin. 



actions, but will ask whether we can reasonably 

 hold that this particular reflex action — comparatively 

 simple though it is — has ever been of selective 

 value to the human species, or to the ancestors 

 thereof? Even in its present fully-formed con- 

 dition it is fairly questionable whether it is of any 

 adaptive value at all. The movement performed is 

 no doubt an adaptive movement ; but is there any 

 occasion upon which the reflex mechanism con- 

 cerned therein can ever have been of adaptive use} 

 Until a man's legs have been paralyzed as to 

 their voluntary motion, he will always promptly 

 withdraw his feet from any injurious source of 

 irritation by means of his conscious intelligence. 

 True, the reflex mechanism secures an almost in- 

 appreciable saving in the time of response to a 

 stimulus, as compared with the time required for 

 response by an act of will ; but the difference is 

 so exceedingly small, that we can hardly suppose 

 the saving of it in this particular case to be 

 a matter of any adaptive — much less selective 

 — importance. Nor is it more easy to suppose 

 that the reflex mechanism has been developed by 

 natural selection for the purpose of replacing volun- 

 tary action when the latter has been destroyed or 

 suspended by grave spinal injury, paralysis, coma, 

 or even ordinary sleep. In short, even if for the 

 sake of argument we allow it to be conceivable that 

 any single human being, ape, or still more distant 

 ancestor, has ever owed its life to the possession of 

 this mechanisni, we may still be certain that not one 

 in a million can have done so. And, if this is the 

 case with regard to the mechanism as now fully 



