58 CONTROLLED NATURAL SELECTION 
It {is possible to arrive at the same con- 
clusion in other ways. There is evidence 
that the destruction of wild animals is in 
many respects similar to that observed in 
man: and that an animal life-table is very 
like a human one. Many are born to die 
almost at once: some die before reaching 
maturity ; others become adults; and a few 
only reach old age. It has therefore been said 
that Natural Selection acts chiefly upon the 
young, and therefore must be most effective 
before the assumption of adult characters: 
and thus cannot be a powerful force in Evo- 
lution. But this is a false argument, apart 
from consideration of juvenile characters. 
Consider one thousand individuals, and sup- 
pose that ten of these become reproductively 
mature ; then it is obvious that the death of 
one of these ten will be equivalent to the 
destruction of one hundred newly born in- 
dividuals; which means that the power of 
Natural Selection, re Evolution, when adults 
are operated upon, is a hundred times as great 
as when newly born individuals are dealt with, 
and still greater when the adults are about 
to reproduce. It follows, therefore, that the 
factors which decide life or death of adults 
are very important ones of Natural Selection. 
