-eared races,
but are not strictly inherited, for they occur or fail in animals of the
same litter.[168] As no wild pigs are known to have analogous appendages,
we have at present no reason to suppose that their appearance is due to
reversion; and if this be so, we are forced to admit that somewhat complex,
though apparently useless, structures may be suddenly developed without the
aid of selection. This case perhaps throws some little light on the manner
of appearance of the hideous fleshy protuberances, though of an essentially
different nature from the above-described appendages, on the cheeks of the
wart-hog or Phacochoerus Africanus.

It is a remarkable fact that the boars of all domesticated breeds have much
shorter tusks than wild boars. Many facts show that with all animals the
state of the hair is much affected by exposure to, or protection from,
climate; and as we see that the state of the hair and teeth are correlated
in Turkish dogs (other analogous facts will be hereafter given), may we not
venture to surmise that the reduction of the tusks in the domestic boar is
related to his coat of bristles being diminished from living under shelter?
On the other hand, as we shall immediately see, the tusks and bristles
reappear with feral boars, which are no longer protected from the weather.
It is not surprising that the tusks should be more affected than the other
teeth; as parts developed to serve as secondary sexual characters are
always liable to much variation.

It is a well-known fact that the young of wild European and Indian
pigs,[169] for the first six months, are longitudinally banded with
light-coloured stripes. This character generally disappears under
domestication. The Turkish domestic pigs, however, have striped young, as
have those of Westphalia, "whatever may be their hue;"[170] whether these
latter pigs belong to the {77} same curly-haired race with the Turkish
swine, I do not know. The pigs which have run wild in Jamaica and the
semi-feral pigs of New Granada, both those which are black and those which
are black with a white band across the stomach, often extending over the
back, have resumed this aboriginal character and produce
longitudinally-striped young. This is likewise the case, at least
occasionally, with the neglected pigs in the Zambesi settlement on the
coast of Africa.[171]

The common belief that all domesticated animals, when they run wild, revert
completely to the character of thei