CHAPTER VI 

 EFFECT OF NATURAL SELECTION 



Natural selection means progressive development • Effect of selection upon 

 the individual • Selection good for the species that can endure it • Selection 

 fatal to a race that cannot endure its hardships • Interest of the individual 

 and the race not identical • A close fit between a species and its environment 

 is inevitable • Apparent exceptions due to absence of severe selection • 

 Adaptation not necessarily perfect • Our standards of selection differ from 

 those of nature • Not all the results of natural selection are useful to us • 

 Our standards often require much readjustment of domesticated species ■ 

 Natural selection always at work • Power of selection to modify type 



Natural selection means progressive development. Natural 

 selection and the survival of the fittest mean progressive develop- 

 ment for the species, because each new generation is born, not 

 from an average, but from a highly selected parentage, limited 

 to the few that best fit the conditions of life as a whole. This 

 means that each new generation is a little better born than the 

 last, and that the " fit " becomes a little closer with each genera- 

 tion, till it becomes approximately perfect if conditions remain 

 constant, all of which is to be counted an improvement of the 

 species as measured by natural standards. 



For example, the bills of woodpeckers are bound to become 

 a little longer and a little better adapted to the needs so long 

 as selection continues, because all below a certain standard are 

 being constantly exterminated. Moreover, in many cases, the 

 standard of selection is likely to rise as time goes on, working 

 still further improvement. Thus deer and wolves frequently 

 run wild in the same regions. The deer live upon vegetation, 

 but the wolves live upon the deer. Both depend on their legs, 

 the one for pursuit, the other for protection. Under conditions 

 such as these, the slow and the crippled deer would be first 



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