The Descent of Man

quired by one sex, generally the male, and then
transmitted to the offspring 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, but 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 acquired simple colours, such as white
or black, 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
having preferred plain black or white. Obscure
tints have often been developed through natu-