Chap. VIII. 
SEXUAL SELECTION. 
277 
would not make tlie one sex different from the other, 
unless indeed their taste for the beautiful differed ; but 
this is a supposition too improbable in the case of any 
animal, excepting man, to be worth considering. There 
are, however, many animals, in which the sexes resemble 
each other, both being furnished with the same orna- 
ments, which analogy would lead us to attribute to the 
agency of sexual selection. In such cases it may be 
suggested with more plausibility, that there has been a 
double or mutual process of sexual selection ; the more 
vigorous and precocious females having selected the 
more attractive and vigorous males, the latter having 
rejected all except the more attractive females. But 
from what we know of the habits of animals, this view 
is hardly probable, the male being generally eager to 
pair with any female. It is more probable that the 
ornaments common to both sexes were acquired by one 
sex, generally the male, and then transmitted to the off- 
spring of both sexes. If, indeed, during a lengthened 
period the males of any species were greatly to exceed 
the females in number, and then during another 
lengthened period under different conditions the reverse 
were to occur, a double, but not simultaneous, process 
of sexual selection might easily be carried on, by which 
the two sexes might be rendered widely different. 
We shall hereafter see that many animals exist, of 
which neither sex is brilliantly coloured or provided 
with special ornaments, and yet the members of both 
sexes or of one alone have probably been modified 
through sexual selection. The absence of bright tints 
or other ornaments may be the result of variations of 
the right kind never having occurred, or of the animals 
themselves preferring simple colours, such as plain black 
or white. Obscure colours have often been acquired 
through natural selection for the sake of protection, and 
