THE DESCENT OR OBIGIN OF MAN 89 



structures -wliicli now appear to us useless will hereafter 

 te proved to be useful, and will therefore come within 

 the range of natural selection. Nevertheless, I did not 

 formerly consider sufficiently the existence of structures 

 which, as far as we can at present judge, are neither 

 heneficial nor injurious ; •^and this I believe to be one 

 of the greatest oversights as yet detected in my work. I 

 may be permitted to say, as some excuse, that I had two 

 distinct objects in view: first, to show that species had not 

 been separately created, and, secondly, that natural selection 

 had been the chief agent of change, though largely aided 

 by the inherited effects of habit, and slightly by the direct 

 action of the surrounding conditions. I was not, however, 

 able to annul the influence of my former belief, then almost 

 universal, that each species had been purposely created; and 

 this led to my tacit assumption that every detail of structure, 

 excepting rudiments, was of some special, though unrecog- 

 nized, service. Any one with this assumption in his mind 

 would naturally extend too far the action of natural selec- 

 tion, either during past or present times. Some of those who 

 admit the principle of evolution, but reject natural selection, 

 seem to forget, when criticising my book, that I had the 

 above two objects in view ; hence if I have erred in giving 

 to natural selection great power, which I am very far from 

 admitting, or in having exaggerated its power, which is in 

 itself probable, I have at least, as I hope, done good service 

 in aiding to overthrow the dogma of separate creations. X 



It is, as I can now see, probable that all organic beings, 

 including man, possess peculiarities of structure which neither 

 are now nor were formerly of any service to them, and which, 

 therefore, are of no physiological importance. We know 

 not what produces the numberless slight differences between 

 the individuals of each species, for reversion only carries the 

 problem a few steps backward; but each peculiarity must 

 have had its efficient cause. If these causes, whatever they 

 may be, were to act more uniformJy and energetically dur- 

 ing a lengthened period (and against this no reason can be 



