On The Parts Of Animals   

hair in the axillae, nor on the pubes, as man has. Their hair, then,
instead of being collected in these parts, is either thickly set over
the whole dorsal surface, as is the case for instance in dogs, or,
sometimes, forms a mane, as in horses and the like, or as in the male
lion where the mane is still more flowing and ample. So, again,
whenever there is a tail of any length, nature decks it with
On the Parts of Animals
By Aristotle
Written 350 B.C.E Part 1
We have next to consider the teeth, and with these the mouth, that is
the cavity which they enclose and form. The teeth have one invariable
office, namely the reduction of food; but besides this general
function they have other special ones, and these differ in different
groups. Thus in some animals the teeth serve as weapons; but this with
a distinction. For there are offensive weapons and there are defensive
weapons; and while in some animals, as the wild Carnivora, the teeth
answer both purposes, in many others, both wild and domesticated, they
serve only for defence. In man the teeth are admirably constructed for
their general office, the front ones being sharp, so as to cut the
food into bits, and the hinder ones broad and flat, so as to grind it
to a pulp; while between these and separating them are the dog-teeth,
which, in accordance with the rule that the mean partakes of both
extremes, share in the characters of those on either side, being broad
in one part but sharp in another. Similar distinctions of shape are
presented by the teeth of other animals, with the exception of those
whose teeth are one and all of the sharp kind. In man, however, the
number and the character even of these sharp teeth have been mainly
determined by the requirements of speech. For the front teeth of man
contribute in many ways to the formation of letter-sounds.
In some animals, however, the teeth, as already said, serve merely for
the reduction of food. When, besides this, they serve as offensive and
defensive weapons, they may either be formed into tusks, as for
instance is the case in swine, or may be sharp-pointed and interlock
with those of the opposite jaw, in which case the animal is said to be
saw-toothed. The explanation of this latter arrangement is as follows.
The strength of such an animal is in its teeth, and these depend for
their efficiency on their sharpness. In order, then, to prevent their
getting blunted by mutual friction, such of them as serve for weapons
fit into each other's interspaces, and are so kept in proper
condition. No animal that has sharp interfitting teeth is at the same
time furnished with tusks. For nature never makes anything superfluous
or in vain. She gives, therefore, tusks to such animals as strike in
fighting, and serrated teeth to such as bite. Sows, for instance, have
no tusks, and accordingly sows bite instead of striking.
A general principle must here be noted, which will be found applicable
not only in this instance but in many others that will occur later on.
Nature allots each weapon, offensive and defensive alike, to those
animals alone that can use it; or, if not to them alone, to them in a
more marked degree; and she allots it in its most perfect state to
those that can use it best; and this whether it be a sting, or a spur,
or horns, or tusks, or what it may of a like kind.
Thus as males are stronger and more choleric than females, it is in
males that such parts as those just mentioned are found, either
exclusively, as in some species, or more fully developed, as in
others. For though females are of course provided with such parts as
are no less necessary to them than to males, the parts, for instance,
which subserve nutrition, they have even these in an inferior degree,
and the parts which answer no such necessary purpose they do not
possess at all. This explains why stags have horns, while does have
none; why the horns of cows are different from those of bulls, and,
similarly, the horns of ewes from those of rams. It explains also why
the females are often without spurs in species where the males are
provided with them, and accounts for similar facts relating to all
other such parts.