EFFECT OF NATURAL SELECTION 8? 



responds at the cost of its life. Manifestly this is because of 

 unusual conditions, for if there were very many naked lights in 

 the world, relatively speaking, these moths would become ex- 

 tinct unless there were a sufficient number of individuals with- 

 out this fatal instinct to keep the numbers good, in which case 

 a new and real fit would be developed. The cause of the 

 present misfit is of course due to the fact that the fatal selection 

 is too rare to greatly affect the species ; that is, the selection is 

 not severe upon the species because, relatively speaking, it is 

 not frequently exercised. 



The foot of the elephant has been mentioned as a disadvan- 

 tage. The immense branching horns of the stag are certainly 

 far from being advantageous to him, or even a good fit with 

 his brushy environment, with which they frequently become 

 entangled. Many a stag has gone down to his death because 

 his horns became entangled in the thicket or locked with those 

 of an adversary, and many pairs of antlers are found lying be- 

 tween two skeletons, mute witnesses of the final death struggle 

 in which the cause of the tragedy was the unfortunate horns 

 that are commonly supposed to be protective. 



The present point is, that while this is far from a good fit, 

 yet the fatal consequences do not follow with sufficient frequency 

 to affect the species. But few males are needed to perpetuate 

 the species, and the small number that lose their lives by means 

 of their unfortunate horns can well be spared, for they will not 

 be needed in the propagation of the new generation. As will be 

 readily seen, defects in females are much more dangerous to 

 species than are defects in males. 



Adaptation not necessarily perfect. The fit between various 

 species and their environment, and the adaptation of their parts 

 to the surrounding conditions, are not, therefore, necessarily 

 perfect. It must be good enough to insure abundance of offspring 

 for the next generation, and that is enough. Any race, therefore, 

 can endure any handicap up to this point and prosper, and that 

 is why natural selection carries improvement up to a certain point 



