The Descent of Man

Before we conclude, it will be well to add a few
remarks on the ornaments of monkeys. In most
of the species the sexes resemble each other in
colour, but in some, as we have seen, the males
differ from the females, especially in the colour
of the naked parts of the skin, in the development
of the beard, whiskers, and mane. Many
species are coloured either in so extraordinary
or so beautiful a manner, and are furnished
with such curious and elegant crests of hair,
that we can hardly avoid looking at these characters
as having been gained for the sake of
ornament. The accompanying figures (Figs. 72
to 76) serve to shew the arrangement of the hair
on the face and head in several species. It is
scarcely conceivable that these crests of hair,
and the strongly contrasted colours of the fur
and skin, can be the result of mere variability
without the aid of selection; and it is inconceivable
that they can be of use in any ordinary
way to these animals. If so, they have probably
been gained through sexual selection, though