The Descent of Man

genitors; and we may infer that the beauty of
our existing species, if we look to the whole
class, has been largely increased since that period,
of which the immature plumage gives us
an indirect record. Many birds, especially those
which live much on the ground, have undoubtedly
been obscurely coloured for the sake of
protection. In some instances the upper exposed
surface of the plumage has been thus coloured
in both sexes, whilst the lower surface in
the males alone has been variously ornamented
through sexual selection. Finally, from the facts
given in these four chapters, we may conclude
that weapons for battle, organs for producing
sound, ornaments of many kinds, bright and
conspicuous colours, have generally been acquired
by the males through variation and
sexual selection, and have been transmitted in
various ways according to the several laws of
inheritance—the females and the young being
left comparatively but little modified. (57. I am
greatly indebted to the kindness of Mr. Sclater