The Descent of Man

ted the more beautiful females; but it is doubtful
whether this double process of selection
would be likely to occur, owing to the greater
eagerness of one sex than the other, and whether
it would be more efficient than selection on
one side alone. It is, therefore, the most probable
view that sexual selection has acted, in the
present class, as far as ornamental characters
are concerned, in accordance with the general
rule throughout the animal kingdom, that is, on
the males; and that these have transmitted their
gradually-acquired colours, either equally or
almost equally, to their offspring of both sexes.
Another point is more doubtful, namely, whether
the successive variations first appeared in
the males after had become nearly mature, or
whilst quite young. In either case sexual selection
must have acted on the male when he had
to compete with rivals for the possession of the
female; and in both cases the characters thus
acquired have been transmitted to both sexes