The emission of Sounds—Vocal sounds—Sounds otherwise produced—Erection
of the dermal appendages, hairs, feathers, &c., under the emotions of
anger and terror—The drawing back of the ears as a preparation for
fighting, and as an expression of anger—Erection of the ears and
raising the head, a sign of attention.
In this and the following chapter I will describe, but only in
sufficient detail to illustrate my subject, the expressive movements,
under different states of the mind, of some few well-known animals. But
before considering them in due succession, it will save much useless
repetition to discuss certain means of expression common to most of
them.
_The emission of Sounds_.—With many kinds of animals, man included, the
vocal organs are efficient in the highest degree as a means of
expression. We have seen, in the last chapter, that when the sensorium
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
animals call for their mothers. When a flock of sheep is scattered, the
ewes bleat incessantly for their lambs, and their mutual pleasure at
coming together is manifest. Woe betide the man who meddles with the
young of the larger and fiercer quadrupeds, if they hear the cry of
distress from their young. Rage leads to the violent exertion of all
the muscles, including those of the voice; and some animals, when
enraged, endeavour to strike terror into their enemies by its power and
harshness, as the lion does by roaring, and the dog by growling. I
infer that their object is to strike terror, because the lion at the
same time erects the hair of its mane, and the dog the hair along its
back, and thus they make themselves appear as large and terrible as
possible. Rival males try to excel and challenge each other by their
voices, and this leads to deadly contests. Thus the use of the voice
will have become associated with the emotion of anger, however it may
be aroused. We have also seen that intense pain, like rage, leads to
violent outcries, and the exertion of screaming by itself gives some
relief; and thus the use of the voice will have become associated with
suffering of any kind.
The cause of widely different sounds being uttered under different
emotions and sensations is a very obscure subject. Nor does the rule
always hold good that there is any marked difference. For instance with
the dog, the bark of anger and that of joy do not differ much, though
they can be distinguished. It is not probable that any precise
explanation of the cause or source of each particular sound, under
different states of the mind, will ever be given. We know that some
animals, after being domesticated, have acquired the habit of uttering
sounds which were not natural to them.[401] Thus domestic dogs, and
even tamed jackals, have learnt to bark, which is a noise not proper to
any species of the genus, with the exception of the _Canis latrans_ of
North America, which is said to bark. Some breeds, also, of the
domestic pigeon have learnt to coo in a new and quite peculiar manner.
The character of the human voice, under the influence of various
emotions, has been discussed by Mr. Herbert Spencer[402] in his
interesting essay on Music. He clearly shows that the voice alters much
under different conditions, in loudness and in quality, that is, in
resonance and _timbre_, in pitch and intervals. No one can listen to an
eloquent orator or preacher, or to a man calling angrily to another, or
to one expressing astonishment, without being struck with the truth of
Mr. Spencer’s remarks. It is curious how early in life the modulation
of the voice becomes expressive. With one of my children, under the age
of two years, I clearly perceived that his humph of assent was rendered
by a slight modulation strongly emphatic; and that by a peculiar whine
his negative expressed obstinate determination. Mr. Spencer further
shows that emotional speech, in all the above respects is intimately
related to vocal music, and consequently to instrumental music; and he
attempts to explain the characteristic qualities of both on
physiological grounds—namely, on “the general law that a feeling is a
stimulus to muscular action.” It may be admitted that the voice is
affected through this law; but the explanation appears to me too
general and vague to throw much light on the various differences, with
the exception of that of loudness, between ordinary speech and
emotional speech, or singing.
This remark holds good, whether we believe that the various qualities
of the voice originated in speaking under the excitement of strong
feelings, and that these qualities have subsequently been transferred
to vocal music; or whether we believe, as I maintain, that the habit of
uttering musical sounds was first developed, as a means of courtship,
in the early progenitors of man, and thus became associated with the
strongest emotions of which they were capable,—namely, ardent love,
rivalry and triumph. That animals utter musical notes is familiar to
every one, as we may daily hear in the singing of birds. It is a more
remarkable fact that an ape, one of the Gibbons, produces an exact
octave of musical sounds, ascending and descending the scale by
halftones; so that this monkey “alone of brute mammals may be said to
sing.”[403] From this fact, and from the analogy of other animals, I
have been led to infer that the progenitors of man probably uttered
musical tones, before they had acquired the power of articulate speech;
and that consequently, when the voice is used under any strong emotion,
it tends to assume, through the principle of association, a musical
character. We can plainly perceive, with some of the lower animals,
that the males employ their voices to please the females, and that they
themselves take pleasure in their own vocal utterances; but why
particular sounds are uttered, and why these give pleasure cannot at
present be explained.
That the pitch of the voice bears some relation to certain states of
feeling is tolerably clear. A person gently complaining of
ill-treatment, or slightly suffering, almost always speaks in a
high-pitched voice. Dogs, when a little impatient, often make a high
piping note through their noses, which at once strikes us as
plaintive;[404] but how difficult it is to know whether the sound is
essentially plaintive, or only appears so in this particular case, from
our having learnt by experience what it means! Rengger, states[405]
that the monkeys (_Cebus azaræ_), which he kept in Paraguay, expressed
astonishment by a half-piping, half-snarling noise; anger or
impatience, by repeating the sound _hu hu_ in a deeper, grunting voice;
and fright or pain, by shrill screams. On the other hand, with mankind,
deep groans and high piercing screams equally express an agony of pain.
Laughter maybe either high or low; so that, with adult men, as Haller
long ago remarked,[406] the sound partakes of the character of the
vowels (as pronounced in German) _O_ and _A_; whilst with children and
women, it has more of the character of _E_ and _I_; and these latter
vowel-sounds naturally have, as Helmholtz has shown, a higher pitch
than the former; yet both tones of laughter equally express enjoyment
or amusement.
In considering the mode in which vocal utterances express emotion, we
are naturally led to inquire into the cause of what is called
“expression” in music. Upon this point Mr. Litchfield, who has long
attended to the subject of music, has been so kind as to give me the
following remarks:—“The question, what is the essence of musical
‘expression’ involves a number of obscure points, which, so far as I am
aware, are as yet unsolved enigmas. Up to a certain point, however, any
law which is found to hold as to the expression of the emotions by
simple sounds must apply to the more developed mode of expression in
song, which may be taken as the primary type of all music. A great part
of the emotional effect of a song depends on the character of the
action by which the sounds are produced. In songs, for instance, which
express great vehemence of passion, the effect often chiefly depends on
the forcible utterance of some one or two characteristic passages which
demand great exertion of vocal force; and it will be frequently noticed
that a song of this character fails of its proper effect when sung by a
voice of sufficient power and range to give the characteristic passages
without much exertion. This is, no doubt, the secret of the loss of
effect so often produced by the transposition of a song from one key to
another. The effect is thus seen to depend not merely on the actual
sounds, but also in part on the nature of the action which produces the
sounds. Indeed it is obvious that whenever we feel the ‘expression’ of
a song to be due to its quickness or slowness of movement—to smoothness
of flow, loudness of utterance, and so on—we are, in fact, interpreting
the muscular actions which produce sound, in the same way in which we
interpret muscular action generally. But this leaves unexplained the
more subtle and more specific effect which we call the _musical_
expression of the song—the delight given by its melody, or even by the
separate sounds which make up the melody. This is an effect indefinable
in language—one which, so far as I am aware, no one has been able to
analyse, and which the ingenious speculation of Mr. Herbert Spencer as
to the origin of music leaves quite unexplained. For it is certain that
the _melodic_ effect of a series of sounds does not depend in the least
on their loudness or softness, or on their _absolute_ pitch. A tune is
always the same tune, whether it is sung loudly or softly, by a child
or a man; whether it is played on a flute or on a trombone. The purely
musical effect of any sound depends on its place in what is technically
called a ‘scale;’ the same sound producing absolutely different effects
on the ear, according as it is heard in connection with one or another
series of sounds.
“It is on this _relative_ association of the sounds that all the
essentially characteristic effects which are summed up in the phrase
‘musical expression,’ depend. But why certain associations of sounds
have such-and-such effects, is a problem which yet remains to be
solved. These effects must indeed, in some way or other, be connected
with the well-known arithmetical relations between the rates of
vibration of the sounds which form a musical scale. And it is
possible—but this is merely a suggestion—that the greater or less
mechanical facility with which the vibrating apparatus of the human
larynx passes from one state of vibration to another, may have been a
primary cause of the greater or less pleasure produced by various
sequences of sounds.”
But leaving aside these complex questions and confining ourselves to
the simpler sounds, we can, at least, see some reasons for the
association of certain kinds of sounds with certain states of mind. A
scream, for instance, uttered by a young animal, or by one of the
members of a community, as a call for assistance, will naturally be
loud, prolonged, and high, so as to penetrate to a distance. For
Helmholtz has shown[407] that, owing to the shape of the internal
cavity of the human ear and its consequent power of resonance, high
notes produce a particularly strong impression. When male animals utter
sounds in order to please the females, they would naturally employ
those which are sweet to the ears of the species; and it appears that
the same sounds are often pleasing to widely different animals, owing
to the similarity of their nervous systems, as we ourselves perceive in
the singing of birds and even in the chirping of certain tree-frogs
giving us pleasure. On the other hand, sounds produced in order to
strike terror into an enemy, would naturally be harsh or displeasing.
Whether the principle of antithesis has come into play with sounds, as
might perhaps have been expected, is doubtful. The interrupted,
laughing or tittering sounds made by man and by various kinds of
monkeys when pleased, are as different as possible from the prolonged
screams of these animals when distressed. The deep grunt of
satisfaction uttered by a pig, when pleased with its food, is widely
different from its harsh scream of pain or terror. But with the dog, as
lately remarked, the bark of anger and that of joy are sounds which by
no means stand in opposition to each other; and so it is in some other
cases.
There is another obscure point, namely, whether the sounds which are
produced under various states of the mind determine the shape of the
mouth, or whether its shape is not determined by independent causes,
and the sound thus modified. When young infants cry they open their
mouths widely, and this, no doubt, is necessary for pouring forth a
full volume of sound; but the mouth then assumes, from a quite distinct
cause, an almost quadrangular shape, depending, as will hereafter be
explained, on the firm closing of the eyelids, and consequent drawing
up of the upper lip. How far this square shape of the mouth modifies
the wailing or crying sound, I am not prepared to say; but we know from
the researches of Helmholtz and others that the form of the cavity of
the mouth and lips determines the nature and pitch of the vowel sounds
which are produced.
It will also be shown in a future chapter that, under the feeling of
contempt or disgust, there is a tendency, from intelligible causes, to
blow out of the mouth or nostrils, and this produces sounds like pooh
or pish. When any one is startled or suddenly astonished, there is an
instantaneous tendency, likewise from an intelligible cause, namely, to
be ready for prolonged exertion, to open the mouth widely, so as to
draw a deep and rapid inspiration. When the next full expiration
follows, the mouth is slightly closed, and the lips, from causes
hereafter to be discussed, are somewhat protruded; and this form of the
mouth, if the voice be at all exerted, produces, according to
Helmholtz, the sound of the vowel _O_. Certainly a deep sound of a
prolonged _Oh!_ may be heard from a whole crowd of people immediately
after witnessing any astonishing spectacle. If, together with surprise,
pain be felt, there is a tendency to contract all the muscles of the
body, including those of the face, and the lips will then be drawn
back; and this will perhaps account for the sound becoming higher and
assuming the character of _Ah!_ or _Ach!_ As fear causes all the
muscles of the body to tremble, the voice naturally becomes tremulous,
and at the same time husky from the dryness of the mouth, owing to the
salivary glands failing to act. Why the laughter of man and the
tittering of monkeys should be a rapidly reiterated sound, cannot be
explained. During the utterance of these sounds, the mouth is
transversely elongated by the corners being drawn backwards and
upwards; and of this fact an explanation will be attempted in a future
chapter. But the whole subject of the differences of the sounds
produced under different states of the mind is so obscure, that I have
succeeded in throwing hardly any light on it; and the remarks which I
have made, have but little significance.
Sound Producing Quills from Tail of a Porcupine. Fig. 11
All the sounds hitherto noticed depend on the respiratory organs; but
sounds produced by wholly different means are likewise expressive.
Rabbits stamp loudly on the ground as a signal to their comrades; and
if a man knows how to do so properly, he may on a quiet evening hear
the rabbits answering him all around. These animals, as well as some
others, also stamp on the ground when made angry. Porcupines rattle
their quills and vibrate their tails when angered; and one behaved in
this manner when a live snake was placed in its compartment. The quills
on the tail are very different from those on the body: they are short,
hollow, thin like a goose-quill, with their ends transversely
truncated, so that they are open; they are supported on long, thin,
elastic foot-stalks. Now, when the tail is rapidly shaken, these hollow
quills strike against each other and produce, as I heard in the
presence of Mr. Bartlett, a peculiar continuous sound. We can, I think,
understand why porcupines have been provided, through the modification
of their protective spines, with this special sound-producing
instrument. They are nocturnal animals, and if they scented or heard a
prowling beast of prey, it would be a great advantage to them in the
dark to give warning to their enemy what they were, and that they were
furnished with dangerous spines. They would thus escape being attacked.
They are, as I may add, so fully conscious of the power of their
weapons, that when enraged they will charge backwards with their spines
erected, yet still inclined backwards.
Many birds during their courtship produce diversified sounds by means
of specially adapted feathers. Storks, when excited, make a loud
clattering noise with their beaks. Some snakes produce a grating or
rattling noise. Many insects stridulate by rubbing together specially
modified parts of their hard integuments. This stridulation generally
serves as a sexual charm or call; but it is likewise used to express
different emotions.[408] Every one who has attended to bees knows that
their humming changes when they are angry; and this serves as a warning
that there is danger of being stung. I have made these few remarks
because some writers have laid so much stress on the vocal and
respiratory organs as having been specially adapted for expression,
that it was advisable to show that sounds otherwise produced serve
equally well for the same purpose.
_Erection of the dermal appendages_.—Hardly any expressive movement is
so general as the involuntary erection of the hairs, feathers and other
dermal appendages; for it is common throughout three of the great
vertebrate classes. These appendages are erected under the excitement
of anger or terror; more especially when these emotions are combined,
or quickly succeed each other. The action serves to make the animal
appear larger and more frightful to its enemies or rivals, and is
generally accompanied by various voluntary movements adapted for the
same purpose, and by the utterance of savage sounds. Mr. Bartlett, who
has had such wide experience with animals of all kinds, does not doubt
that this is the case; but it is a different question whether the power
of erection was primarily acquired for this special purpose.
I will first give a considerable body of facts showing how general this
action is with mammals, birds and reptiles; retaining what I have to
say in regard to man for a future chapter. Mr. Sutton, the intelligent
keeper in the Zoological Gardens, carefully observed for me the
Chimpanzee and Orang; and he states that when they are suddenly
frightened, as by a thunderstorm, or when they are made angry, as by
being teased, their hair becomes erect. I saw a chimpanzee who was
alarmed at the sight of a black coalheaver, and the hair rose all over
his body; he made little starts forward as if to attack the man,
without any real intention of doing so, but with the hope, as the
keeper remarked, of frightening him. The Gorilla, when enraged, is
described by Mr. Ford[409] as having his crest of hair “erect and
projecting forward, his nostrils dilated, and his under lip thrown
down; at the same time uttering his characteristic yell, designed, it
would seem, to terrify his antagonists.” I saw the hair on the Anubis
baboon, when angered bristling along the back, from the neck to the
loins, but not on the rump or other parts of the body. I took a stuffed
snake into the monkey-house, and the hair on several of the species
instantly became erect; especially on their tails, as I particularly
noticed with the _Cereopithecus nictitans_. Brehm states[410] that the
_Midas œdipus_ (belonging to the American division) when excited erects
its mane, in order, as he adds, to make itself as frightful as
possible.
With the Carnivora the erection of the hair seems to be almost
universal, often accompanied by threatening movements, the uncovering
of the teeth and the utterance of savage growls. In the Herpestes, I
have seen the hair on end over nearly the whole body, including the
tail; and the dorsal crest is erected in a conspicuous manner by the
Hyaena and Proteles. The enraged lion erects his mane. The bristling of
the hair along the neck and back of the dog, and over the whole body of
the cat, especially on the tail, is familiar to every one. With the cat
it apparently occurs only under fear; with the dog, under anger and
fear; but not, as far as I have observed, under abject fear, as when a
dog is going to be flogged by a severe gamekeeper. If, however, the dog
shows fight, as sometimes happens, up goes his hair. I have often
noticed that the hair of a dog is particularly liable to rise, if he is
half angry and half afraid, as on beholding some object only
indistinctly seen in the dusk.
I have been assured by a veterinary surgeon that he has often seen the
hair erected on horses and cattle, on which he had operated and was
again going to operate. When I showed a stuffed snake to a Peccary, the
hair rose in a wonderful manner along its back; and so it does with the
boar when enraged. An Elk which gored a man to death in the United
States, is described as first brandishing his antlers, squealing with
rage and stamping on the ground; “at length his hair was seen to rise
and stand on end,” and then he plunged forward to the attack.[411] The
hair likewise becomes erect on goats, and, as I hear from Mr. Blyth, on
some Indian antelopes. I have seen it erected on the hairy Ant-eater;
and on the Agouti, one of the Rodents. A female Bat,[412] which reared
her young under confinement, when any one looked into the cage “erected
the fur on her back, and bit viciously at intruding fingers.”
Birds belonging to all the chief Orders ruffle their feathers when
angry or frightened. Every one must have seen two cocks, even quite
young birds, preparing to fight with erected neck-hackles; nor can
these feathers when erected serve as a means of defence, for
cock-fighters have found by experience that it is advantageous to trim
them. The male Ruff (_Machetes pugnæ_) likewise erects its collar of
feathers when fighting. When a dog approaches a common hen with her
chickens, she spreads out her wings, raises her tail, ruffles all her
feathers, and looking as ferocious as possible, dashes at the intruder.
The tail is not always held in exactly the same position; it is
sometimes so much erected, that the central feathers, as in the
accompanying drawing, almost touch the back. Swans, when angered,
likewise raise their wings and tail, and erect their feathers. They
open their beaks, and make by paddling little rapid starts forwards,
against any one who approaches the water’s edge too closely. Tropic
birds[413] when disturbed on their nests are said not to fly away, but
“merely to stick out their feathers and scream.” The Barn-owl, when
approached “instantly swells out its plumage, extends its wings and
tail, hisses and clacks its mandibles with force and rapidity.”[414] So
do other kinds of owls. Hawks, as I am informed by Mr. Jenner Weir,
likewise ruffle their feathers, and spread out their wings and tail
under similar circumstances. Some kinds of parrots erect their
feathers; and I have seen this action in the Cassowary, when angered at
the sight of an Ant-eater. Young cuckoos in the nest, raise their
feathers, open their mouths widely, and make themselves as frightful as
possible.
Hen Driving Away a Dog from Her Chickens. Fig. 12
{illust. caption = FIG. 12—Hen driving away a dog from her chickens.
Drawn from life by Mr. Wood.}
Swan Driving Away an Intruder. Fig 13
{illust. caption = FIG. 13.—Swan driving away an intruder. Drawn from
life by Mr. Wood.}
Small birds, also, as I hear from Mr. Weir, such as various finches,
buntings and warblers, when angry, ruffle all their feathers, or only
those round the neck; or they spread out their wings and tail-feathers.
With their plumage in this state, they rush at each other with open
beaks and threatening gestures. Mr. Weir concludes from his large
experience that the erection of the feathers is caused much more by
anger than by fear. He gives as an instance a hybrid goldfinch of a
most irascible disposition, which when approached too closely by a
servant, instantly assumes the appearance of a ball of ruffled
feathers. He believes that birds when frightened, as a general rule,
closely adpress all their feathers, and their consequently diminished
size is often astonishing. As soon as they recover from their fear or
surprise, the first thing which they do is to shake out their feathers.
The best instances of this adpression of the feathers and apparent
shrinking of the body from fear, which Mr. Weir has noticed, has been
in the quail and grass-parrakeet.[415] The habit is intelligible in
these birds from their being accustomed, when in danger, either to
squat on the ground or to sit motionless on a branch, so as to escape
detection. Though, with birds, anger may be the chief and commonest
cause of the erection of the feathers, it is probable that young
cuckoos when looked at in the nest, and a hen with her chickens when
approached by a dog, feel at least some terror. Mr. Tegetmeier informs
me that with game-cocks, the erection of the feathers on the head has
long been recognized in the cock-pit as a sign of cowardice.
The males of some lizards, when fighting together during their
courtship, expand their throat pouches or frills, and erect their
dorsal crests.[416] But Dr. Günther does not believe that they can
erect their separate spines or scales.
We thus see how generally throughout the two higher vertebrate classes,
and with some reptiles, the dermal appendages are erected under the
influence of anger and fear. The movement is effected, as we know from
Kolliker’s interesting discovery, by the contraction of minute,
unstriped, involuntary muscles,[417] often called _arrectores pili_,
which are attached to the capsules of the separate hairs, feathers, &c.
By the contraction of these muscles the hairs can be instantly erected,
as we see in a dog, being at the same time drawn a little out of their
sockets; they are afterwards quickly depressed. The vast number of
these minute muscles over the whole body of a hairy quadruped is
astonishing. The erection of the hair is, however, aided in some cases,
as with that on the head of a man, by the striped and voluntary muscles
of the underlying _panniculus carnosus_. It is by the action of these
latter muscles, that the hedgehog erects its spines. It appears, also,
from the researches of Leydig[418] and others, that striped fibres
extend from the panniculus to some of the larger hairs, such as the
vibrissae of certain quadrupeds. The _arrectores pili_ contract not
only under the above emotions, but from the application of cold to the
surface. I remember that my mules and dogs, brought from a lower and
warmer country, after spending a night on the bleak Cordillera, had the
hair all over their bodies as erect as under the greatest terror. We
see the same action in our own _goose-skin_ during the chill before a
fever-fit. Mr. Lister has also found,[419] that tickling a neighbouring
part of the skin causes the erection and protrusion of the hairs.
From these facts it is manifest that the erection of the dermal
appendages is a reflex action, independent of the will; and this action
must be looked at, when, occurring under the influence of anger or
fear, not as a power acquired for the sake of some advantage, but as an
incidental result, at least to a large extent, of the sensorium being
affected. The result, in as far as it is incidental, may be compared
with the profuse sweating from an agony of pain or terror.
Nevertheless, it is remarkable how slight an excitement often suffices
to cause the hair to become erect; as when two dogs pretend to fight
together in play. We have, also, seen in a large number of animals,
belonging to widely distinct classes, that the erection of the hair or
feathers is almost always accompanied by various voluntary movements—by
threatening gestures, opening the mouth, uncovering the teeth,
spreading out of the wings and tail by birds, and by the utterance of
harsh sounds; and the purpose of these voluntary movements is
unmistakable. Therefore it seems hardly credible that the co-ordinated
erection of the dermal appendages, by which the animal is made to
appear larger and more terrible to its enemies or rivals, should be
altogether an incidental and purposeless result of the disturbance of
the sensorium. This seems almost as incredible as that the erection by
the hedgehog of its spines, or of the quills by the porcupine, or of
the ornamental plumes by many birds during their courtship, should all
be purposeless actions.
We here encounter a great difficulty. How can the contraction of the
unstriped and involuntary _arrectores pili_ have been co-ordinated with
that of various voluntary muscles for the same special purpose? If we
could believe that the arrectores primordially had been voluntary
muscles, and had since lost their stripes and become involuntary, the
case would be comparatively simple. I am not, however, aware that there
is any evidence in favour of this view; although the reversed
transition would not have presented any great difficulty, as the
voluntary muscles are in an unstriped condition in the embryos of the
higher animals, and in the larvae of some crustaceans. Moreover in the
deeper layers of the skin of adult birds, the muscular network is,
according to Leydig,[420] in a transitional condition; the fibres
exhibiting only indications of transverse striation.
Another explanation seems possible. We may admit that originally the
_arrectores pili_ were slightly acted on in a direct manner, under the
influence of rage and terror, by the disturbance of the nervous system;
as is undoubtedly the case with our so-called _goose-skin_ before a
fever-fit. Animals have been repeatedly excited by rage and terror
during many generations; and consequently the direct effects of the
disturbed nervous system on the dermal appendages will almost certainly
have been increased through habit and through the tendency of
nerve-force to pass readily along accustomed channels. We shall find
this view of the force of habit strikingly confirmed in a future
chapter, where it will be shown that the hair of the insane is affected
in an extraordinary manner, owing to their repeated accesses of fury
and terror. As soon as with animals the power of erection had thus been
strengthened or increased, they must often have seen the hairs or
feathers erected in rival and enraged males, and the bulk of their
bodies thus increased. In this case it appears possible that they might
have wished to make themselves appear larger and more terrible to their
enemies, by voluntarily assuming a threatening attitude and uttering
harsh cries; such attitudes and utterances after a time becoming
through habit instinctive. In this manner actions performed by the
contraction of voluntary muscles might have been combined for the same
special purpose with those effected by involuntary muscles. It is even
possible that animals, when excited and dimly conscious of some change
in the state of their hair, might act on it by repeated exertions of
their attention and will; for we have reason to believe that the will
is able to influence in an obscure manner the action of some unstriped
or involuntary muscles, as in the period of the peristaltic movements
of the intestines, and in the contraction of the bladder. Nor must we
overlook the part which variation and natural selection may have
played; for the males which succeeded in making themselves appear the
most terrible to their rivals, or to their other enemies, if not of
overwhelming power, will on an average have left more offspring to
inherit their characteristic qualities, whatever these may be and
however first acquired, than have other males.
_The inflation of the body, and other means of exciting fear in an
enemy_.—Certain Amphibians and Reptiles, which either have no spines to
erect, or no muscles by which they can be erected, enlarge themselves
when alarmed or angry by inhaling air. This is well known to be the
case with toads and frogs. The latter animal is made, in AEsop’s fable
of the ‘Ox and the Frog,’ to blow itself up from vanity and envy until
it burst. This action must have been observed during the most ancient
times, as, according to Mr. Hensleigh Wedgwood,[421] the word _toad_
expresses in all the languages of Europe the habit of swelling. It has
been observed with some of the exotic species in the Zoological
Gardens; and Dr. Günther believes that it is general throughout the
group. Judging from analogy, the primary purpose probably was to make
the body appear as large and frightful as possible to an enemy; but
another, and perhaps more important secondary advantage is thus gained.
When frogs are seized by snakes, which are their chief enemies, they
enlarge themselves wonderfully; so that if the snake be of small size,
as Dr. Günther informs me, it cannot swallow the frog, which thus
escapes being devoured.
Chameleons and some other lizards inflate themselves when angry. Thus a
species inhabiting Oregon, the _Tapaya Douglasii_, is slow in its
movements and does not bite, but has a ferocious aspect; “when
irritated it springs in a most threatening manner at anything pointed
at it, at the same time opening its mouth wide and hissing audibly,
after which it inflates its body, and shows other marks of anger.”[422]
Several kinds of snakes likewise inflate themselves when irritated. The
puff-adder (_Clotho arietans_) is remarkable in this respect; but I
believe, after carefully watching these animals, that they do not act
thus for the sake of increasing their apparent bulk, but simply for
inhaling a large supply of air, so as to produce their surprisingly
loud, harsh, and prolonged hissing sound. The Cobras-de-capello, when
irritated, enlarge themselves a little, and hiss moderately; but, at
the same time they lift their heads aloft, and dilate by means of their
elongated anterior ribs, the skin on each side of the neck into a large
flat disk,—the so-called hood. With their widely opened mouths, they
then assume a terrific aspect. The benefit thus derived ought to be
considerable, in order to compensate for the somewhat lessened rapidity
(though this is still great) with which, when dilated, they can strike
at their enemies or prey; on the same principle that a broad, thin
piece of wood cannot be moved through the air so quickly as a small
round stick. An innocuous snake, the _Trovidonotus macrophthalmus_, an
inhabitant of India, likewise dilates its neck when irritated; and
consequently is often mistaken for its compatriot, the deadly
Cobra.[423] This resemblance perhaps serves as some protection to the
Tropidonotus. Another innocuous species, the Dasypeltis of South
Africa, blows itself out, distends its neck, hisses and darts at an
intruder.[424] Many other snakes hiss under similar circumstances. They
also rapidly vibrate their protruded tongues; and this may aid in
increasing their terrific appearance.
Snakes possess other means of producing sounds besides hissing. Many
years ago I observed in South America that a venomous Trigonocephalus,
when disturbed, rapidly vibrated the end of its tail, which striking
against the dry grass and twigs produced a rattling noise that could be
distinctly heard at the distance of six feet.[425] The deadly and
fierce _Echis carinata_ of India produces “a curious prolonged, almost
hissing sound in a very different manner, namely by rubbing the sides
of the folds of its body against each other,” whilst the head remains
in almost the same position. The scales on the sides, and not on other
parts of the body, are strongly keeled, with the keels toothed like a
saw; and as the coiled-up animal rubs its sides together, these grate
against each other.[426] Lastly, we have the well-known case of the
Rattle-snake. He who has merely shaken the rattle of a dead snake, can
form no just idea of the sound produced by the living animal. Professor
Shaler states that it is indistinguishable from that made by the male
of a large Cicada (an Homopterous insect), which inhabits the same
district.[427] In the Zoological Gardens, when the rattle-snakes and
puff-adders were greatly excited at the same time, I was much struck at
the similarity of the sound produced by them; and although that made by
the rattle-snake is louder and shriller than the hissing of the
puff-adder, yet when standing at some yards distance I could scarcely
distinguish the two. For whatever purpose the sound is produced by the
one species, I can hardly doubt that it serves for the same purpose in
the other species; and I conclude from the threatening gestures made at
the same time by many snakes, that their hissing,—the rattling of the
rattle-snake and of the tail of the Trigonocephalus,—the grating of the
scales of the Echis,—and the dilatation of the hood of the Cobra,—all
subserve the same end, namely, to make them appear terrible to their
enemies.[428]
It seems at first a probable conclusion that venomous snakes, such as
the foregoing, from being already so well defended by their
poison-fangs, would never be attacked by any enemy; and consequently
would have no need to excite additional terror. But this is far from
being the case, for they are largely preyed on in all quarters of the
world by many animals. It is well known that pigs are employed in the
United States to clear districts infested with rattle-snakes, which
they do most effectually.[429] In England the hedgehog attacks and
devours the viper. In India, as I hear from Dr. Jerdon, several kinds
of hawks, and at least one mammal, the Herpestes, kill cobras and other
venomous species;[430] and so it is in South Africa. Therefore it is by
no means improbable that any sounds or signs by which the venomous
species could instantly make themselves recognized as dangerous, would
be of more service to them than to the innocuous species which would
not be able, if attacked, to inflict any real injury.
Having said thus much about snakes, I am tempted to add a few remarks
on the means by which the rattle of the rattle-snake was probably
developed. Various animals, including some lizards, either curl or
vibrate their tails when excited. This is the case with many kinds of
snakes.[431] In the Zoological Gardens, an innocuous species, the
_Coronella Sayi_, vibrates its tail so rapidly that it becomes almost
invisible. The Trigonocephalus, before alluded to, has the same habit;
and the extremity of its tail is a little enlarged, or ends in a bead.
In the Lachesis, which is so closely allied to the rattle-snake that it
was placed by Linnaeus in the same genus, the tail ends in a single,
large, lancet-shaped point or scale. With some snakes the skin, as
Professor Shaler remarks, “is more imperfectly detached from the region
about the tail than at other parts of the body.” Now if we suppose that
the end of the tail of some ancient American species was enlarged, and
was covered by a single large scale, this could hardly have been cast
off at the successive moults. In this case it would have been
permanently retained, and at each period of growth, as the snake grew
larger, a new scale, larger than the last, would have been formed above
it, and would likewise have been retained. The foundation for the
development of a rattle would thus have been laid; and it would have
been habitually used, if the species, like so many others, vibrated its
tail whenever it was irritated. That the rattle has since been
specially developed to serve as an efficient sound-producing
instrument, there can hardly be a doubt; for even the vertebrae
included within the extremity of the tail have been altered in shape
and cohere. But there is no greater improbability in various
structures, such as the rattle of the rattle-snake,—the lateral scales
of the Echis,—the neck with the included ribs of the Cobra,—and the
whole body of the puff-adder,—having been modified for the sake of
warning and frightening away their enemies, than in a bird, namely, the
wonderful Secretary-hawk (_Gypogeranus_) having had its whole frame
modified for the sake of killing snakes with impunity. It is highly
probable, judging from what we have before seen, that this bird would
ruffle its feathers whenever it attacked a snake; and it is certain
that the Herpestes, when it eagerly rushes to attack a snake, erects
the hair all over its body, and especially that on its tail.[432] We
have also seen that some porcupines, when angered or alarmed at the
sight of a snake, rapidly vibrate their tails, thus producing a
peculiar sound by the striking together of the hollow quills. So that
here both the attackers and the attacked endeavour to make themselves
as dreadful as possible to each other; and both possess for this
purpose specialised means, which, oddly enough, are nearly the same in
some of these cases. Finally we can see that if, on the one hand, those
individual snakes, which were best able to frighten away their enemies,
escaped best from being devoured; and if, on the other hand, those
individuals of the attacking enemy survived in larger numbers which
were the best fitted for the dangerous task of killing and devouring
venomous snakes;—then in the one case as in the other, beneficial
variations, supposing the characters in question to vary, would
commonly have been preserved through the survival of the fittest.
_The Drawing back and pressure of the Ears to the Head_.—The ears
through their movements are highly expressive in many animals; but in
some, such as man, the higher apes, and many ruminants, they fail in
this respect. A slight difference in position serves to express in the
plainest manner a different state of mind, as we may daily see in the
dog; but we are here concerned only with the ears being drawn closely
backwards and pressed to the head. A savage frame of mind is thus
shown, but only in the case of those animals which fight with their
teeth; and the care which they take to prevent their ears being seized
by their antagonists, accounts for this position. Consequently, through
habit and association, whenever they feel slightly savage, or pretend
in their play to be savage, their ears are drawn back. That this is the
true explanation may be inferred from the relation which exists in very
many animals between their manner of fighting and the retraction of
their ears.
All the Carnivora fight with their canine teeth, and all, as far as I
have observed, draw their ears back when feeling savage. This may be
continually seen with dogs when fighting in earnest, and with puppies
fighting in play. The movement is different from the falling down and
slight drawing back of the ears, when a dog feels pleased and is
caressed by his master. The retraction of the ears may likewise be seen
in kittens fighting together in their play, and in full-grown cats when
really savage, as before illustrated in fig. 9 (p. 58). Although their
ears are thus to a large extent protected, yet they often get much torn
in old male cats during their mutual battles. The same movement is very
striking in tigers, leopards, &c., whilst growling over their food in
menageries. The lynx has remarkably long ears; and their retraction,
when one of these animals is approached in its cage, is very
conspicuous, and is eminently expressive of its savage disposition.
Even one of the Eared Seals, the _Otariapusilla_, which has very small
ears, draws them backwards, when it makes a savage rush at the legs of
its keeper.
When horses fight together they use their incisors for biting, and
their fore-legs for striking, much more than they do their hind-legs
for kicking backwards. This has been observed when stallions have
broken loose and have fought together, and may likewise be inferred
from the kind of wounds which they inflict on each other. Every one
recognizes the vicious appearance which the drawing back of the ears
gives to a horse. This movement is very different from that of
listening to a sound behind. If an ill-tempered horse in a stall is
inclined to kick backwards, his ears are retracted from habit, though
he has no intention or power to bite. But when a horse throws up both
hind-legs in play, as when entering an open field, or when just touched
by the whip, he does not generally depress his ears, for he does not
then feel vicious. Guanacoes fight savagely with their teeth; and they
must do so frequently, for I found the hides of several which I shot in
Patagonia deeply scored. So do camels; and both these animals, when
savage, draw their ears closely backwards. Guanacoes, as I have
noticed, when not intending to bite, but merely to spit their offensive
saliva from a distance at an intruder, retract their ears. Even the
hippopotamus, when threatening with its widely-open enormous mouth a
comrade, draws back its small ears, just like a horse.
Now what a contrast is presented between the foregoing animals and
cattle, sheep, or goats, which never use their teeth in fighting, and
never draw back their ears when enraged! Although sheep and goats
appear such placid animals, the males often join in furious contests.
As deer form a closely related family, and as I did not know that they
ever fought with their teeth, I was much surprised at the account given
by Major Ross King of the Moose-deer in Canada. He says, when“two males
chance to meet, laying back their ears and gnashing their teeth
together, they rush at each other with appalling fury.”[433] But Mr.
Bartlett informs me that some species of deer fight savagely with their
teeth, so that the drawing back of the ears by the moose accords with
our rule. Several kinds of kangaroos, kept in the Zoological Gardens,
fight by scratching with their fore-feet and by kicking with their
hind-legs; but they never bite each other, and the keepers have never
seen them draw back their ears when angered. Rabbits fight chiefly by
kicking and scratching, but they likewise bite each other; and I have
known one to bite off half the tail of its antagonist. At the
commencement of their battles they lay back their ears, but afterwards,
as they bound over and kick each other, they keep their ears erect, or
move them much about.
Mr. Bartlett watched a wild boar quarrelling rather savagely with his
sow; and both had their mouths open and their ears drawn backwards. But
this does not appear to be a common action with domestic pigs when
quarrelling. Boars fight together by striking upwards with their tusks;
and Mr. Bartlett doubts whether they then draw back their ears.
Elephants, which in like manner fight with their tusks, do not retract
their ears, but, on the contrary, erect them when rushing at each other
or at an enemy.
The rhinoceroses in the Zoological Gardens fight with their nasal
horns, and have never been seen to attempt biting each other except in
play; and the keepers are convinced that they do not draw back their
ears, like horses and dogs, when feeling savage. The following
statement, therefore, by Sir S. Baker[434] is inexplicable, namely,
that a rhinoceros, which he shot in North Africa, “had no ears; they
had been bitten off close to the head by another of the same species
while fighting; and this mutilation is by no means uncommon.”
Lastly, with respect to monkeys. Some kinds, which have moveable ears,
and which fight with their teeth—for instance the _Cereopithecus
ruber_—draw back their ears when irritated just like dogs; and they
then have a very spiteful appearance. Other kinds, as the _Inuus
ecaudatus_, apparently do not thus act. Again, other kinds—and this is
a great anomaly in comparison with most other animals—retract their
ears, show their teeth, and jabber, when they are pleased by being
caressed. I observed this in two or three species of Macacus, and in
the _Cynopithecus niger_. This expression, owing to our familiarity
with dogs, would never be recognized as one of joy or pleasure by those
unacquainted with monkeys.
_Erection of the Ears_.—This movement requires hardly any notice. All
animals which have the power of freely moving their ears, when they are
startled, or when they closely observe any object, direct their ears to
the point towards which they are looking, in order to hear any sound
from this quarter. At the same time they generally raise their heads,
as all their organs of sense are there situated, and some of the
smaller animals rise on their hind-legs. Even those kinds which squat
on the ground or instantly flee away to avoid danger, generally act
momentarily in this manner, in order to ascertain the source and nature
of the danger. The head being raised, with erected ears and eyes
directed forwards, gives an unmistakable expression of close attention
to any animal.