The Descent of Man

tection; so that they have probably been gained
by the males through sexual selection, and then
transferred to the females and the young. It is,
however, possible that the males may have selected
the more attractive females; and if these
transmitted their characters to their offspring of
both sexes, the same results would follow as
from the selection of the more attractive males
by the females. But there is evidence that this
contingency has rarely, if ever, occurred in any
of those groups of birds in which the sexes are
generally alike; for, if even a few of the successive
variations had failed to be transmitted to
both sexes, the females would have slightly
exceeded the males in beauty. Exactly the reverse
occurs under nature; for, in almost every
large group in which the sexes generally resemble
each other, the males of some few species
are in a slight degree more brightly coloured
than the females. It is again possible that
the females may have selected the more beautiful
males, these males having reciprocally selec-