SEXUAL SELECTION IN RELATION TO MAN 781 



meuts whieh lie retains, and the abnormal reversions to 

 which he is occasionally liable — are facts which cannot be 

 disputed. They have long been known, but until recently 

 they told us nothing with respect to the origin of man. 

 Now when viewed by the light of our knowledge of the 

 whole organic world, their meaning is unmistakable. The 

 great principle of evolution stands up clear and firm, when 

 these groups of facts are considered in connection with oth- 

 ers, such as the mutual affinities of the members of the same 

 group, their geographical distribution in past and present 

 times, and their geological succession. It is incredible that 

 all these facts should speak falsely. He who is not content 

 to look, like a savage, at the phenomena of nature as dis- 

 connected, cannot any longer believe that man is the work 

 of a separate act of creation. He will be forced to admit 

 that the close resemblance of the embryo of man to that, 

 for instance, of a dog — the construction of his skull, limbs, 

 and whole frame on the same plan with that of other mam- 

 mals, independently of the uses to which the parts may be 

 put — the occasional reappearance of various structures, for 

 instance of several muscles, which man does not normally 

 possess, but which are common to the Quadrumana — and a 

 crowd of analogous facts — all point in the plainest manner 

 to the conclusion that man is the co-descendant with other 

 mammals of a common progenitor. 



"We have seen that man incessantly presents individual 

 difEerences in all parts of his body and in his mental facul- 

 ties. These differences or variations seem to be induced by 

 the same general causes, and to obey the same laws as with 

 the lower animals. In both cases similar laws of inheri- 

 tance prevail. Man tends to increase at a greater rate than 

 his means of subsistence; consequently he is occasionally 

 subjected to a severe struggle for existence, and natural 

 selection will have effected whatever lies within its scope. 

 A succession of strongly marked variations of a similar na- 

 ture is by no means requisite; slight fluctuating differences 

 in the individual suffice for the work of natural selection; 



