is strongly excited, the muscles of the body are generally thrown into
violent action; and as a consequence, loud sounds are uttered, however
silent the animal may generally be, and although the sounds may be of
no use. Hares and rabbits for instance, never, I believe, use their
vocal organs except in the extremity of suffering; as, when a wounded
hare is killed by the sportsman, or when a young rabbit is caught by a
stoat. Cattle and horses suffer great pain in silence; but when this is
excessive, and especially when associated with terror, they utter
fearful sounds. I have often recognized, from a distance on the Pampas,
the agonized death-bellow of the cattle, when caught by the lasso and
hamstrung. It is said that horses, when attacked by wolves, utter loud
and peculiar screams of distress.
Involuntary and purposeless contractions of the muscles of the chest
and glottis, excited in the above manner, may have first given rise to
the emission of vocal sounds. But the voice is now largely used by many
animals for various purposes; and habit seems to have played an
important part in its employment under other circumstances. Naturalists
have remarked, I believe with truth, that social animals, from
habitually using their vocal organs as a means of intercommunication,
use them on other occasions much more freely than other animals. But
there are marked exceptions to this rule, for instance, with the
rabbit. The principle, also, of association, which is so widely
extended in its power, has likewise played its part. Hence it follows
that the voice, from having been habitually employed as a serviceable
aid under certain conditions, inducing pleasure, pain, rage, &c., is
commonly used whenever the same sensations or emotions are excited,
under quite different conditions, or in a lesser degree.
The sexes of many animals incessantly call for each other during the
breeding-season; and in not a few cases, the male endeavours thus to
charm or excite the female. This, indeed, seems to have been the
primeval use and means of development of the voice, as I have attempted
to show in my Descent of Man. Thus the use of the vocal organs will
have become associated with the anticipation of the strongest pleasure
which animals are capable of feeling. Animals which live in society
often call to each other when separated, and evidently feel much joy at
meeting; as we see with a horse, on the return of his companion, for
whom he has been neighing. The mother calls incessantly for her lost
young ones; for instance, a cow for her calf; and the young of many
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