The Descent of Man

exposed to danger whilst sitting on the eggs. It
should also be borne in mind that the males are
not only in a slight degree less conspicuously
coloured than the females, but are smaller and
weaker. They have, moreover, not only acquired
the maternal instinct of incubation, but are
less pugnacious and vociferous than the females,
and in one instance have simpler vocal organs.
Thus an almost complete transposition of
the instincts, habits, disposition, colour, size,
and of some points of structure, has been effected
between the two sexes.
Now if we might assume that the males in the
present class have lost some of that ardour
which is usual to their sex, so that they no longer
search eagerly for the females; or, if we
might assume that the females have become
much more numerous than the males—and in
the case of one Indian Turnix the females are
said to be "much more commonly met with
than the males" (26. Jerdon, 'Birds of India,' vol.