The Descent of Man

iod of reproduction arrives; consequently if
dangerous to the young, they will be eliminated
through natural selection. Thus we can understand
how it is that variations arising late in
life have so often been preserved for the ornamentation
of the males; the females and the
young being left almost unaffected, and therefore
like each other. With species having a distinct
summer and winter plumage, the males of
which either resemble or differ from the females
during both seasons or during the summer
alone, the degrees and kinds of resemblance
between the young and the old are exceedingly
complex; and this complexity apparently depends
on characters, first acquired by the males,
being transmitted in various ways and degrees,
as limited by age, sex, and season.
As the young of so many species have been but
little modified in colour and in other ornaments,
we are enabled to form some judgment
with respect to the plumage of their early pro-