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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