Chap. VIII. 
SEXUAL SELECTION. 
299 s 
adult male parents. If only a few of tlie successive 
variations in brightness were to occur at a late age,, 
the adult male would be only a little brighter than the 
young male ; and such cases are common. 
In this illustration I have assumed that the young 
varied in a manner which was of no service to them 
but many characters proper to the adult male would be 
actually injurious to the young, — as bright colours from 
making them conspicuous, or horns of large size from 
expending much vital force. Such variations in the 
young would promptly be eliminated through natural 
selection. With the adult and experienced males, on 
the other hand, the advantage thus derived in their 
rivalry with other males would often more than counter- 
balance exposure to some degree of danger. Thus we 
can understand how it is that variations which must 
originally have appeared rather late in life have alone 
or in chief part been preserved for the development of 
secondary sexual characters ; and the remarkable coin- 
cidence between the periods of variability and of sexual 
selection is intelligible. 
As variations which give to the male an advantage 
in fighting with other males, or in finding, securing,, 
or charming the female, would be of no use to the 
female, they will not have been preserved in this sex 
either during youth or maturity. Consequently such 
variations would be extremely liable to be lost ; and the 
female, as far as these characters are concerned, would be 
left unmodified, excepting in so far as she may have re- 
ceived them by transference from the male. No doubt if 
the female varied and transferred serviceable characters 
to her male offspring, these would be favoured through 
sexual selection ; and then both sexes would thus far be 
modified in the same manner. But I shall hereafter 
have to recur to these more intricate contingencies. 
