84 DOMESTICATED ANIMALS AND PLANTS 
killed off, and the fleetest would go scot free. On the other 
hand, the fleetest wolves would be best fed and the laggards 
would die of hunger. In this way both species would develop 
high speed and great wariness, and this development would pro- 
gress further and further as the competition grew keener with 
each passing generation. The horse has almost certainly come 
up through a similar experience in ages past. 
Effect of selection upon the individual. This effect is two- 
fold. First of all, it sharpens the wits of the individual if he 
has any, and develops to the utmost whatever faculties he may 
possess. If by this he is able to withstand the competition, he is 
in every way the better for it. 
If, however, as generally happens where the selective process 
is severe, it is only the few that are able to withstand, then the 
masses will go down in the struggle; so that the total effects 
of selection may be said to be hard upon all but the few individ- 
uals, and its chief advantage is to the race as a whole. 
Selection good for the species that can endure it. By this we 
mean that if a number of individuals sufficient to keep up the 
population are able to meet the demands of selection, then the 
species will rapidly progress; and up to this point the more 
severe the selection the better for the race. This is an impor- 
tant distinction in all evolution that should never be forgotten, 
for it is only when undergoing severe selection that species 
change much in their characters from generation to generation. 
Next to sudden calamity the greatest misfortune that can 
happen to a species or a race is a long succession of easy times, 
when the whole population settles down to a dead level of inac- 
tivity. Then are the days of extinction imminent, for matters 
will not always run in an accustomed rut, and when the days of 
sudden and unaccustomed changes come, they are likely to find 
things unprepared. 
Selection fatal to a race that cannot endure its hardships. 
It matters little to the race what happens to individuals, so long 
as a sufficient number prosper, It is vital, however, that a 
