PRESENT ASPECTS OF EVOLUTION 283 



struggle for life.' As fast as the faculties are multiplied, so 

 fast does it become possible for the several members of a 

 species to have various kinds of superiorities over one another. 

 While one saves its life by higher speed, another does the like 

 by clearer vision, another by keener scent, another by quicker 

 hearing, another by greater strength, another by unusual power 

 of enduring cold or hunger, another by special sagacity, an- 

 other by special timidity, another by special courage ; and 

 others by other bodily and mental attributes. Now it is un- 

 questionably true that, other things equal, each of these attri- 

 butes, giving its possessor an extra chance of life, is likely to 

 be transmitted to posterity. But there seems no reason to 

 suppose that it will be increased in subsequent generations by 

 natural selection. That it may be thus increased, the individ- 

 uals not possessing more than average endowments of it must 

 be more frequently killed off than individuals highly endowed 

 with it ; and this can happen only when the attribute is one of 

 greater importance, for the time being, than most of the other 

 attributes. If those members of the species which have but 

 ordinary shares of it, nevertheless survive by virtue of other 

 superiorities which they severally possess, then it is not easy 

 to see how this particular attribute can be developed by natu- 

 ral selection in subsequent generations. The probability seems 

 rather to be that, by gamogenesis, this extra endowment will, 

 on the average, be diminished in posterity — just serving in the 

 long run to compensate the deficient endowments of other in- 

 dividuals whose special powers lie in other directions, and so 

 to keep up the normal structure of the species. The working 

 out of the process is here somewhat difficult to follow ; but it 

 appears to me that as fast as the number of bodily and mental 

 faculties increases, and as fast as the maintenance of life comes 

 to depend less on the amount of any one, and more on the 

 combined action of all, so fast does the production of special- 

 ties of character by natural selection alone become difficult. 

 Particularly does this seem to be so with a species so multi. 

 tudinous in its powers as mankind, and above all does it seem 

 to be so with such of the human powers as have but minor 

 shares in aiding the struggle for life — the sesthetio faculties 

 for example." — Spencer, " Principles of Biology," g 166. 



