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The Expression of Emotion in Man and Animals by Charles Darwin

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Change of colour in the hair--Trembling of the muscles--
Modified secretions--Perspiration--Expression of extreme pain--
Of rage, great joy, and terror--Contrast between the emotions
which cause and do not cause expressive movements--Exciting and
depressing states of the mind--Summary.

WE now come to our third Principle, namely, that certain actions which we
recognize as expressive of certain states of the mind, are the direct
result of the constitution of the nervous system, and have been from
the first independent of the will, and, to a large extent, of habit.
When the sensorium is strongly excited nerve-force is generated in excess,
and is transmitted in certain directions, dependent on the connection
of the nerve-cells, and, as far as the muscular system is concerned,
on the nature of the movements which have been habitually practised.
Or the supply of nerve-force may, as it appears, be interrupted.
Of course every movement which we make is determined by the constitution
of the nervous system; but actions performed in obedience to the will,
or through habit, or through the principle of antithesis, are here
as far as possible excluded. Our present subject is very obscure,
but, from its importance, must be discussed at some little length;
and it is always advisable to perceive clearly our ignorance.

The most striking case, though a rare and abnormal one,
which can be adduced of the direct influence of the nervous system,
when strongly affected, on the body, is the loss of colour in the hair,
which has occasionally been observed after extreme terror or grief.
One authentic instance has been recorded, in the case of a man
brought out for execution in India, in which the change of colour
was so rapid that it was perceptible to the eye.[1]

Another good case is that of the trembling of the muscles,
which is common to man and to many, or most, of the lower animals.
Trembling is of no service, often of much disservice,
and cannot have been at first acquired through the will,
and then rendered habitual in association with any emotion.
I am assured by an eminent authority that young children do
not tremble, but go into convulsions under the circumstances
which would induce excessive trembling in adults. Trembling is
excited in different individuals in very different degrees.
and by the most diversified causes,--by cold to the surface,
before fever-fits, although the temperature of the body is then
above the normal standard; in blood-poisoning, delirium tremens,
and other diseases; by general failure of power in old age;
by exhaustion after excessive fatigue; locally from severe injuries,
such as burns; and, in an especial manner, by the passage of
a catheter. Of all emotions, fear notoriously is the most apt
to induce trembling; but so do occasionally great anger and joy.
I remember once seeing a boy who had just shot his first snipe
on the wing, and his hands

[1] See the interesting cases collected by M. G. Pouchet in the `Revue
des Deux Mondes,' January 1, 1872, p. 79. An instance was also
brought some years ago before the British Association at Belfast.
trembled to such a degree from delight, that he could not for
some time reload his gun; and I have heard of an exactly similar
case with an Australian savage, to whom a gun had been lent.
Fine music, from the vague emotions thus excited,
causes a shiver to run down the backs of some persons.
There seems to be very little in common in the above several
physical causes and emotions to account for trembling;
and Sir J. Paget, to whom I am indebted for several of the above
statements, informs me that the subject is a very obscure one.
As trembling is sometimes caused by rage, long before exhaustion
can have set in, and as it sometimes accompanies great joy,
it would appear that any strong excitement of the nervous system
interrupts the steady flow of nerve-force to the muscles.[2]

The manner in which the secretions of the alimentary canal
and of certain glands--as the liver, kidneys, or mammae are
affected by strong emotions, is another excellent instance
of the direct action of the sensorium on these organs,
independently of the will or of any serviceable associated habit.
There is the greatest difference in different persons in the parts
which are thus affected, and in the degree of their affection.

The heart, which goes on uninterruptedly beating night and day in so
wonderful a manner, is extremely sensitive to external stimulants.
The great physiologist, Claude Bernard,[3] has shown bow the least
excitement of a sensitive nerve reacts on the heart; even when a nerve
is touched so slightly that no pain can possibly be felt by the animal
under experiment. Hence when the mind is strongly excited, we might
expect that it would instantly affect in a direct manner the heart;
and this is universally acknowledged and felt to be the case.
Claude Bernard also repeatedly insists, and this deserves especial notice,
that when the heart is affected it reacts on the brain; and the state
of the brain again reacts through the pneumo-gastric nerve on the heart;
so that under any excitement there will be much mutual action and reaction
between these, the two most important organs of the body.

[2] Muller remarks (`Elements of Physiology,' Eng. translat. vol. ii. p.
934) that when the feelings are very intense, "all the spinal nerves become
affected to the extent of imperfect paralysis, or the excitement of trembling
of the whole body."

[3] `Lecons sur les Prop. des Tissus Vivants,' 1866, pp. 457-466.

The vaso-motor system, which regulates the diameter of the
small arteries, is directly acted on by the sensorium, as we see
when a man blushes from shame; but in this latter case the checked
transmission of nerve-force to the vessels of the face can,
I think, be partly explained in a curious manner through habit.
We shall also be able to throw some light, though very little,
on the involuntary erection of the hair under the emotions
of terror and rage. The secretion of tears depends, no doubt,
on the connection of certain nerve-cells; but here again we can
trace some few of the steps by which the flow of nerve-force through
the requisite channels has become habitual under certain emotions.

A brief consideration of the outward signs of some of the stronger
sensations and emotions will best serve to show us, although vaguely,
in how complex a manner the principle under consideration of the direct
action of the excited nervous system of the body, is combined with
the principle of habitually associated, serviceable movements.

When animals suffer from an agony of pain, they generally
writhe about with frightful contortions; and those which
habitually use their voices utter piercing cries or groans.
Almost every muscle of the body is brought into strong action.
With man the mouth may be closely compressed, or more commonly
the lips are retracted, with the teeth clenched or ground together.
There is said to be "gnashing of teeth" in hell; and I
have plainly heard the grinding of the molar teeth of a cow
which was suffering acutely from inflammation of the bowels.
The female hippopotamus in the Zoological Gardens, when she
produced her young, suffered greatly; she incessantly walked about,
or rolled on her sides, opening and closing her jaws, and clattering
her teeth together.[4] With man the eyes stare wildly as in
horrified astonishment, or the brows are heavily contracted.
Perspiration bathes the body, and drops trickle down the face.
The circulation and respiration are much affected.
Hence the nostrils are generally dilated and often quiver; or the
breath may be held until the blood stagnates in the purple face.
If the agony be severe and prolonged, these signs all change;
utter prostration follows, with fainting or convulsions.

A sensitive nerve when irritated transmits some influence to the
nerve-cell, whence it proceeds; and this transmits its influence,
first to the corresponding nerve-cell on the opposite side of the body,
and then upwards and downwards along the cerebro-spinal column
to other nerve-cells, to a greater or less extent, according to
the strength of the excitement; so that, ultimately, the whole
nervous system maybe affected.[5] This involuntary transmission
of nerve-force may or may not be accompanied by consciousness.
Why the irritation of a nerve-cell should generate or liberate
nerve-force is not known; but that this is the case seems to be
the conclusion arrived at by all the greatest physiologists,
such as Muller, Virchow, Bernard, &c.[6] As Mr. Herbert Spencer remarks,
it may be received as an "unquestionable truth that, at any moment,
the existing quantity of liberated nerve-force, which in an inscrutable
way produces in us the state we call feeling, MUST expend itself
in some direction--MUST generate an equivalent manifestation
of force somewhere;" so that, when the cerebro-spinal system is
highly excited and nerve-force is liberated in excess, it may be
expended in intense sensations, active thought, violent movements,
or increased activity of the glands.[7] Mr. Spencer further maintains
that an "overflow of nerve-force, undirected by any motive,
will manifestly take the most habitual routes; and, if these do
not suffice, will next overflow into the less habitual ones."
Consequently the facial and respiratory muscles, which are
the most used, will be apt to be first brought into action;
then those of the upper extremities, next those of the lower,
and finally those of the whole body.[8]

[4] Mr. Bartlett, "Notes on the Birth of
a Hippopotamus," Proc. Zoolog. Soc. 1871, p. 255.

[5] See, on this subject, Claude Bernard, `Tissus Vivants,' 1866, pp.
316, 337, 358. Virchow expresses himself to almost exactly the same
effect in his essay "Ueber das Ruckenmark" (Sammlung wissenschaft.
Vortrage, 1871, s. 28).

An emotion may be very strong, but it will have little tendency
to induce movements of any kind, if it has not commonly led to
voluntary action for its relief or gratification; and when movements
are excited, their nature is, to a large extent, determined by those
which have often and voluntarily been performed for some definite
end under the same emotion. Great pain urges all animals, and has
urged them during endless generations, to make the most violent
and diversified efforts to escape from the cause of suffering.
Even when a limb or other separate part of the body is hurt,
we often see a tendency to shake it, as if to shake off the cause,
though this may obviously be impossible. Thus a habit of exerting
with the utmost force all the muscles will have been established,
whenever great suffering is experienced. As the muscles of the chest
and vocal organs are habitually used, these will be particularly liable
to be acted on, and loud, harsh screams or cries will be uttered.
But the advantage derived from outcries has here probably come
into play in an important manner; for the young of most animals,
when in distress or danger, call loudly to their parents for aid,
as do the members of the same community for mutual aid.

[6] Muller (`Elements of Physiology,' Eng. translat. vol. ii. p. 932) in
speaking of the nerves, says, "any sudden change of condition of whatever kind
sets the nervous principle into action." See Virchow and Bernard on the same
subject in passages in the two works referred to in my last foot-note.

[7] H. Spencer, `Essays, Scientific, Political,' &c., Second Series,
1863, pp. 109, 111.

[8] Sir H. Holland, in speaking (`Medical Notes and Reflexions,'
1839, p. 328) of that curious state of body called the _fidgets_,
remarks that it seems due to "an accumulation of some cause
of irritation which requires muscular action for its relief."

Another principle, namely, the internal consciousness
that the power or capacity of the nervous system is limited,
will have strengthened, though in a subordinate degree,
the tendency to violent action under extreme suffering.
A man cannot think deeply and exert his utmost muscular force.
As Hippocrates long ago observed, if two pains are felt
at the same time, the severer one dulls the other.
Martyrs, in the ecstasy of their religious fervour have often,
as it would appear, been insensible to the most horrid tortures.
Sailors who are going to be flogged sometimes take a piece of lead
into their mouths, in order to bite it with their utmost force,
and thus to bear the pain. Parturient women prepare to exert
their muscles to the utmost in order to relieve their sufferings.

We thus see that the undirected radiation of nerve-force from
the nerve-cells which are first affected--the long-continued habit
of attempting by struggling to escape from the cause of suffering--
and the consciousness that voluntary muscular exertion relieves pain,
have all probably concurred in giving a tendency to the most violent,
almost convulsive, movements under extreme suffering; and such movements,
including those of the vocal organs, are universally recognized
as highly expressive of this condition.

As the mere touching of a sensitive nerve reacts in a direct manner
on the heart, severe pain will obviously react on it in like manner,
but far more energetically. Nevertheless, even in this case,
we must not overlook the indirect effects of habit on the heart,
as we shall see when we consider the signs of rage.

When a man suffers from an agony of pain, the perspiration
often trickles down his face; and I have been assured by a
veterinary surgeon that he has frequently seen drops falling
from the belly and running down the inside of the thighs
of horses, and from the bodies of cattle, when thus suffering.
He has observed this, when there has been no struggling
which would account for the perspiration. The whole body
of the female hippopotamus, before alluded to, was covered
with red-coloured perspiration whilst giving birth to her young.
So it is with extreme fear; the same veterinary has often
seen horses sweating from this cause; as has Mr. Bartlett
with the rhinoceros; and with man it is a well-known symptom.
The cause of perspiration bursting forth in these cases is
quite obscure; but it is thought by some physiologists to be
connected with the failing power of the capillary circulation;
and we know that the vasomotor system, which regulates
the capillary circulation, is much influenced by the mind.
With respect to the movements of certain muscles of the face
under great suffering, as well as from other emotions,
these will be best considered when we treat of the special
expressions of man and of the lower animals.

We will now turn to the characteristic symptoms of Rage. Under this
powerful emotion the action of the heart is much accelerated,[9]
or it may be much disturbed. The face reddens, or it becomes purple
from the impeded return of the blood, or may turn deadly pale.
The respiration is laboured, the chest heaves, and the dilated
nostrils quiver. The whole body often trembles. The voice is affected.
The teeth are clenched or ground together, and the muscular
system is commonly stimulated to violent, almost frantic action.
But the gestures of a man in this state usually differ from the purposeless
writhings and struggles of one suffering from an agony of pain;
for they represent more or less plainly the act of striking or fighting
with an enemy.

All these signs of rage are probably in large part, and some of them
appear to be wholly, due to the direct action of the excited sensorium.
But animals of all kinds, and their progenitors before them,
when attacked or threatened by an enemy, have exerted their utmost
powers in fighting and in defending themselves. Unless an animal
does thus act, or has the intention, or at least the desire,
to attack its enemy, it cannot properly be said to be enraged.
An inherited habit of muscular exertion will thus have been gained
in association with rage; and this will directly or indirectly
affect various organs, in nearly the same manner as does
great bodily suffering.

[9] I am much indebted to Mr. A. H. Garrod for having informed
me of M. Lorain's work on the pulse, in which a sphygmogram
of a woman in a rage is given; and this shows much difference
in the rate and other characters from that of the same woman
in her ordinary state.

The heart no doubt will likewise be affected in a direct manner;
but it will also in all probability be affected through habit;
and all the more so from not being under the control of the will.
We know that any great exertion which we voluntarily make, affects the heart,
through mechanical and other principles which need not here be considered;
and it was shown in the first chapter that nerve-force flows
readily through habitually used channels,--through the nerves of
voluntary or involuntary movement, and through those of sensation.
Thus even a moderate amount of exertion will tend to act on the heart;
and on the principle of association, of which so many instances have
been given, we may feel nearly sure that any sensation or emotion,
as great pain or rage, which has habitually led to much muscular action,
will immediately influence the flow of nerve-force to the heart,
although there may not be at the time any muscular exertion.

The heart, as I have said, will be all the more readily affected through
habitual associations, as it is not under the control of the will.
A man when moderately angry, or even when enraged, may command the movements
of his body, but he cannot prevent his heart from beating rapidly.
His chest will perhaps give a few heaves, and his nostrils just quiver,
for the movements of respiration are only in part voluntary.
In like manner those muscles of the face which are least obedient
to the will, will sometimes alone betray a slight and passing emotion.
The glands again are wholly independent of the will, and a man suffering
from grief may command his features, but cannot always prevent
the tears from coming into his eyes. A hungry man, if tempting food
is placed before him, may not show his hunger by any outward gesture,
but he cannot check the secretion of saliva.

Under a transport of Joy or of vivid Pleasure, there is a strong tendency
to various purposeless movements, and to the utterance of various sounds.
We see this in our young children, in their loud laughter, clapping
of hands, and jumping for joy; in the bounding and barking of a dog
when going out to walk with his master; and in the frisking of a horse
when turned out into an open field. Joy quickens the circulation,
and this stimulates the brain, which again reacts on the whole body.
The above purposeless movements and increased heart-action may be
attributed in chief part to the excited state of the sensorium,[10]
and to the consequent undirected overflow, as Mr. Herbert Spencer insists,
of nerve-force. It deserves notice, that it is chiefly the anticipation
of a pleasure, and not its actual enjoyment, which leads to purposeless and
extravagant movements of the body, and to the utterance of various sounds.
We see this in our children when they expect any great pleasure or treat;
and dogs, which have been bounding about at

[10] How powerfully intense joy excites the brain, and how
the brain reacts on the body, is well shown in the rare cases of
Psychical Intoxication. Dr. J. Crichton Browne (`Medical Mirror,'
1865) records the case of a young man of strongly nervous temperament,
who, on hearing by a telegram that a fortune had been bequeathed him,
first became pale, then exhilarated, and soon in the highest spirits,
but flushed and very restless. He then took a walk with a friend
for the sake of tranquillising himself, but returned staggering
in his gait, uproariously laughing, yet irritable in temper,
incessantly talking, and singing loudly in the public streets.
It was positively ascertained that he had not touched any
spirituous liquor, though every one thought that he was intoxicated.
Vomiting after a time came on, and the half-digested contents of his
stomach were examined, but no odour of alcohol could be detected.
He then slept heavily, and on awaking was well, except that
he suffered from headache, nausea, and prostration of strength.
the sight of a plate of food, when they get it do not show their
delight by any outward sign, not even by wagging their tails.
Now with animals of all kinds, the acquirement of almost all
their pleasures, with the exception of those of warmth and rest,
are associated, and have long been associated with active movements,
as in the hunting or search for food, and in their courtship.
Moreover, the mere exertion of the muscles after long rest
or confinement is in itself a pleasure, as we ourselves feel,
and as we see in the play of young animals. Therefore on this
latter principle alone we might perhaps expect, that vivid pleasure
would be apt to show itself conversely in muscular movements.

With all or almost all animals, even with birds, Terror causes the body
to tremble. The skin becomes pale, sweat breaks out, and the hair bristles.
The secretions of the alimentary canal and of the kidneys are increased,
and they are involuntarily voided, owing to the relaxation of the
sphincter muscles, as is known to be the case with man, and as I have
seen with cattle, dogs, cats, and monkeys. The breathing is hurried.
The heart beats quickly, wildly, and violently; but whether it pumps
the blood more efficiently through the body may be doubted, for the
surface seems bloodless and the strength of the muscles soon fails.
In a frightened horse I have felt through the saddle the beating
of the heart so plainly that I could have counted the beats.
The mental faculties are much disturbed. Utter prostration soon follows,
and even fainting. A terrified canary-bird has been seen not only to
tremble and to turn white about the base of the bill, but to faint;[11]
and I once caught a robin in a room, which fainted so completely,
that for a time I thought it dead.

[11] Dr. Darwin, `Zoonomia,' 1794, vol. i. p. 148.

Most of these symptoms are probably the direct result,
independently of habit, of the disturbed state of the sensorium;
but it is doubtful whether they ought to be wholly thus accounted for.
When an animal is alarmed it almost always stands motionless for a moment,
in order to collect its senses and to ascertain the source of danger,
and sometimes for the sake of escaping detection. But headlong flight
soon follows, with no husbanding of the strength as in fighting,
and the animal continues to fly as long as the danger lasts,
until utter prostration, with failing respiration and circulation,
with all the muscles quivering and profuse sweating, renders further
flight impossible. Hence it does not seem improbable that the principle
of associated habit may in part account for, or at least augment,
some of the above-named characteristic symptoms of extreme terror.

That the principle of associated habit has played an important part in
causing the movements expressive of the foregoing several strong emotions
and sensations, we may, I think, conclude from considering firstly,
some other strong emotions which do not ordinarily require for their
relief or gratification any voluntary movement; and secondly the contrast
in nature between the so-called exciting and depressing states of the mind.
No emotion is stronger than maternal love; but a mother may feel the deepest
love for her helpless infant, and yet not show it by any outward sign;
or only by slight caressing movements, with a gentle smile and tender eyes.
But let any one intentionally injure her infant, and see what a change!
how she starts up with threatening aspect, how her eyes sparkle and her
face reddens, how her bosom heaves, nostrils dilate, and heart beats;
for anger, and not maternal love, has habitually led to action.
The love between the opposite sexes is widely different from maternal love;
and when lovers meet, we know that their hearts beat quickly,
their breathing is hurried, and their faces flush; for this love is not
inactive like that of a mother for her infant.

A man may have his mind filled with the blackest hatred or suspicion,
or be corroded with envy or jealousy, but as these feelings do not at once
lead to action, and as they commonly last for some time, they are not shown
by any outward sign, excepting that a man in this state assuredly does
not appear cheerful or good-tempered. If indeed these feelings break out
into overt acts, rage takes their place, and will be plainly exhibited.
Painters can hardly portray suspicion, jealousy, envy, &c., except by the aid
of accessories which tell the tale; and poets use such vague and fanciful
expressions as "green-eyed jealousy." Spenser describes suspicion as
"Foul, ill-favoured, and grim, under his eyebrows looking still askance,"
&c.; Shakespeare speaks of envy "as lean-faced in her loathsome case;"
and in another place he says, "no black envy shall make my grave;"
and again as "above pale envy's threatening reach."

Emotions and sensations have often been classed as exciting or depressing.
When all the organs of the body and mind,--those of voluntary and
involuntary movement, of perception, sensation, thought, &c.,--perform
their functions more energetically and rapidly than usual, a man or animal
may be said to be excited, and, under an opposite state, to be depressed.
Anger and joy are from the first exciting emotions, and they naturally lead,
more especially the former, to energetic movements, which react on the heart
and this again on the brain. A physician once remarked to me as a proof
of the exciting nature of anger, that a man when excessively jaded
will sometimes invent imaginary offences and put himself into a passion,
unconsciously for the sake of reinvigorating himself; and since hearing
this remark, I have occasionally recognized its full truth.

Several other states of mind appear to be at first exciting,
but soon become depressing to an extreme degree. When a mother
suddenly loses her child, sometimes she is frantic with grief,
and must be considered to be in an excited state; she walks
wildly about, tears her hair or clothes, and wrings her hands.
This latter action is perhaps due to the principle of antithesis,
betraying an inward sense of helplessness and that nothing can be done.
The other wild and violent movements may be in part explained
by the relief experienced through muscular exertion, and in part
by the undirected overflow of nerve-force from the excited sensorium.
But under the sudden loss of a beloved person, one of the first
and commonest thoughts which occurs, is that something more
might have been done to save the lost one. An excellent
observer,[12] in describing the behaviour of a girl at the sudden
death of her father, says she "went about the house wringing
her hands like a creature demented, saying `It was her fault;'
`I should never have left him;' `If I had only sat up with him,'
" &c. With such ideas vividly present before the mind,
there would arise, through the principle of associated habit,
the strongest tendency to energetic action of some kind.

As soon as the sufferer is fully conscious that nothing can be done,
despair or deep sorrow takes the place of frantic grief.
The sufferer sits motionless, or gently rocks to and fro;
the circulation becomes languid; respiration is almost forgotten,
and deep sighs are drawn.

[12] "Mrs. Oliphant, in her novel of `Miss Majoribanks,' p. 362. All this
reacts on the brain, and prostration soon follows with collapsed muscles
and dulled eyes. As associated habit no longer prompts the sufferer
to action, he is urged by his friends to voluntary exertion, and not
to give way to silent, motionless grief. Exertion stimulates the heart,
and this reacts on the brain, and aids the mind to bear its heavy load.

Pain, if severe, soon induces extreme depression or prostration;
but it is at first a stimulant and excites to action, as we see when we
whip a horse, and as is shown by the horrid tortures inflicted in foreign
lands on exhausted dray-bullocks, to rouse them to renewed exertion.
Fear again is the most depressing of all the emotions; and it soon
induces utter, helpless prostration, as if in consequence of,
or in association with, the most violent and prolonged attempts to escape
from the danger, though no such attempts have actually been made.
Nevertheless, even extreme fear often acts at first as a powerful stimulant.
A man or animal driven through terror to desperation, is endowed with
wonderful strength, and is notoriously dangerous in the highest degree.

On the whole we may conclude that the principle of the direct
action of the sensorium on the body, due to the constitution
of the nervous system, and from the first independent of the will,
has been highly influential in determining many expressions.
Good instances are afforded by the trembling of the muscles,
the sweating of the skin, the modified secretions of the alimentary
canal and glands, under various emotions and sensations.
But actions of this kind are often combined with others,
which follow from our first principle, namely, that actions
which have often been of direct or indirect service,
under certain states of the mind, in order to gratify or relieve
certain sensations, desires, &c., are still performed under
analogous circumstances through mere habit although of no service.
We have combinations of this kind, at least in part, in the
frantic gestures of rage and in the writhings of extreme pain;
and, perhaps, in the increased action of the heart and of
the respiratory organs. Even when these and other emotions
or sensations are aroused in a very feeble manner, there will
still be a tendency to similar actions, owing to the force
of long-associated habit; and those actions which are least
under voluntary control will generally be longest retained.
Our second principle of antithesis has likewise occasionally
come into play.

Finally, so many expressive movements can be explained, as I trust
will be seen in the course of this volume, through the three
principles which have now been discussed, that we may hope hereafter
to see all thus explained, or by closely analogous principles.
It is, however, often impossible to decide how much weight ought
to be attributed, in each particular case, to one of our principles,
and how much to another; and very many points in the theory
of Expression remain inexplicable. CHAPTER IV.


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 now that some animals,
after being domesticated, have acquired the habit of uttering
sounds which were not natural to them.[1] 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[2]
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.

[1] See the evidence on this head in my `Variation of Animals
and Plants under Domestication,' vol. i. p. 27. On the cooing
of pigeons, vol. i. pp. 154, 155.

[2] `Essays, Scientific, Political, and Speculative,' 1858.
`The Origin and Function of Music,' p. 359.

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."[3] 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.

[3] `The Descent of Man,' 1870, vol. ii. p. 332. The words
quoted are from Professor Owen. It has lately been shown
that some quadrupeds much lower in the scale than monkeys,
namely Rodents, are able to produce correct musical tones:
see the account of a singing Hesperomys, by the Rev. S. Lockwood,
in the `American Naturalist,' vol. v. December, 1871, p. 761.

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;[4] 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[5] that the monkeys
(_Cebus azaroe_), 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,[6] 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.

[4] Mr. Tylor (`Primitive Culture,' 1871, vol. i. p. 166), in his
discussion on this subject, alludes to the whining of the dog.

[5] `Naturgeschichte der Saugethiere von Paraguay,' 1830, s. 46.

[6] Quoted by Gratiolet, `De la Physionomie,' 1865, p. 115.

"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[7] 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.

[7] `Theorie Physiologique de la Musique,' Paris, 1868, P. 146.
Helmholtz has also fully discussed in this profound work the relation
of the form of the cavity of the mouth to the production of vowel-sounds.

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.

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 tail of 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.[8] 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.

[8] I have given some details on this subject in my `Descent
of Man,' vol. i. pp. 352, 384.

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[9]
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[10] that the _Midas aedipus_ (belonging to
the American division) when excited erects its mane, in order,
as he adds, to make itself as frightful as possible.

[9] As quoted in Huxley's `Evidence as to Man's Place in Nature,'
1863, p. 52.

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.[11] 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,[12] 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."

[10] Illust. Thierleben, 1864, B. i. s. 130.

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 pugnax_)
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[13] 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."[14] So do other kinds of owls.
Hawks, as I am

[11] The Hon. J. Caton, Ottawa Acad. of Nat. Sciences, May, 1868, pp.
36, 40. For the _Capra, AEgagrus_, `Land and Water,' 1867, p. 37.

[12] `Land and Water,' July 20, 1867, p. 659.

[13] _Phaeton rubricauda_: `Ibis,' vol. iii. 1861, p. 180.

{illust. caption = FIG. 12--Hen driving away a dog from her chickens.
Drawn from life by Mr. Wood. 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.
[14] On the _Strix flammea_, Audubon, `Ornithological Biography,'
1864, vol. ii. p. 407. I have observed other cases in the
Zoological Gardens.Small birds, also, as I hear from Mr. Weir,
such as various finches, buntings and warblers, when angry,
{illust. caption = FIG. 13.--Swan driving away an intruder.
Drawn from life by Mr. Wood.}

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.[15] 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.[16]
But Dr. Gunther 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,[17]
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[18] 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,[19] that tickling
a neighbouring part of the skin causes the erection and protrusion
of the hairs.

[15] _Melopsittacus undulatus_. See an account of its habits
by Gould, `Handbook of Birds of Australia,' 1865, vol. ii. p. 82.

[16] See, for instance, the account which I have given
(`Descent of Man,' vol. ii. p. 32) of an Anolis and Draco.

[17] These muscles are described in his well-known works.
I am greatly indebted to this distinguished observer for having
given me in a letter information on this same subject.

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.

[18] `Lehrbuch der Histologie des Menschen,' 1857, s. 82. I owe
to Prof. W. Turner's kindness an extract from this work.

[19] `Quarterly Journal of Microscopical Science,' 1853, vol. i. p. 262.

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,[20] 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.

[20] `Lehrbuch der Histologie,' 1857, s. 82.

_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,[21] 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. Gunther 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. Gunther informs me, it cannot swallow the frog,
which thus escapes being devoured.

[21] `Dictionary of English Etymology,' p. 403.

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."[22]

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.[23] This resemblance perhaps serves as some protection
to the Tropidonotus.

[21] See the account of the habits of this animal by Dr, Cooper, as quoted
in `Nature,' April 27, 1871, p. 512.

[22] Dr. Gunther, `Reptiles of British India,' p. 262.

Another innocuous species, the Dasypeltis of South Africa,
blows itself out, distends its neck, hisses and darts at an
intruder.[24] 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.[25]
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.[26] 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.[27] 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.[28]

[24] Mr. J. Mansel Weale, `Nature,' April 27, 1871, p. 508.

[25] `Journal of Researches during the Voyage of the "Beagle,"
' 1845, p. 96. I have compared the rattling thus produced
with that of the Rattle-snake.

[26] See the account by Dr. Anderson, Proc. Zool. Soc. 1871, p. 196.

[27] The `American Naturalist,' Jan. 1872, p. 32. I regret that I cannot
follow Prof. Shaler in believing that the rattle has been developed,
by the aid of natural selection, for the sake of producing sounds which
deceive and attract birds, so that they may serve as prey to the snake.

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

{note [27] continued} I do not, however, wish to doubt
that the sounds may occasionally subserve this end.
But the conclusion at which I have arrived, viz. that the rattling
serves as a warning to would-be devourers, appears to me much
more probable, as it connects together various classes of facts.
If this snake had acquired its rattle and the habit of rattling,
for the sake of attracting prey, it does not seem probable that it
would have invariably used its instrument when angered or disturbed.
Prof. Shaler takes nearly the same view as I do of the manner
of development of the rattle; and I have always held this opinion
since observing the Trigonocephalus in South America.

[28] From the accounts lately collected, and given in the `Journal
of the Linnean Society,' by Airs. Barber, on the habits of the snakes
of South Africa; and from the accounts published by several writers,
for instance by Lawson, of the rattle-snake in North America,--it does
not seem improbable that the terrific appearance of snakes and the sounds
produced by them, may likewise serve in procuring prey, by paralysing,
or as it is sometimes called fascinating, the smaller animals.
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.[29] 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;[30]
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.[31]
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.[32] 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.

[29] See the account by Dr. R. Brown, in Proc. Zool. Soc. 1871, p. 39.
He says that as soon as a pig sees a snake it rushes upon it; and a snake
makes off immediately on the appearance of a pig.

[30] Dr. Gunther remarks (`Reptiles of British India,' p. 340) on the
destruction of cobras by the ichneumon or herpestes, and whilst the cobras
are young by the jungle-fowl. It is well known that the peacock also
eagerly kills snakes.

[31] Prof. Cope enumerates a number of kinds in his `Method of Creation
of Organic Types,' read before the American Phil. Soc., December 15th,
1871, p. 20. Prof. Cope takes the same view as I do of the use
of the gestures and sounds made by snakes. I briefly alluded to this
subject in the last edition of my `Origin of Species.' Since the passages
in the text above have been printed, I have been pleased to find that
Mr. Henderson (`The American Naturalist,' May, 1872, p. 260) also takes
a similar view of the use of the rattle, namely "in preventing an attack
from being made."

_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.

[32] Mr. des Voeux, in Proc. Zool. Soc. 1871, p. 3.

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."[33] 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.

[33] `The Sportsman and Naturalist in Canada,' 1866, p. 53. p. 53.{sic}

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[34] 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.

[34] `The Nile Tributaries of Abyssinia,' 1867, p. 443.

_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.


The Dog, various expressive movements of--Cats--Horses--Ruminants--Monkeys,
their expression of joy and affection--Of pain--Anger--Astonishment
and Terror.

_The Dog_.--I have already described (figs. 5 and 1) the appearance
of a dog approaching another dog with hostile intentions,
namely, with erected ears, eyes intently directed forwards,
hair on the neck and back bristling, gait remarkably stiff,
with the tail upright and rigid. So familiar is this appearance
to us, that an angry man is sometimes said "to have his back up."
Of the above points, the stiff gait and upright tail alone
require further discussion. Sir C. Bell remarks[1] that,
when a tiger or wolf is struck by its keeper and is suddenly
roused to ferocity, every muscle is in tension, and the limbs
are in an attitude of strained exertion, prepared to spring.
This tension of the muscles and consequent stiff gait may be
accounted for on the principle of associated habit, for anger
has continually led to fierce struggles, and consequently
to all the muscles of the body having been violently exerted.
There is also reason to suspect that the muscular
system requires some short preparation, or some degree
of innervation, before being brought into strong action.
My own sensations lead me to this inference; but I cannot
discover that it is a conclusion admitted by physiologists.
Sir J. Paget, however, informs me that when muscles are suddenly
contracted with the greatest force, without any preparation,
they are liable to be ruptured, as when a man slips unexpectedly;
but that this rarely occurs when an action, however violent,
is deliberately performed.

[1] `The Anatomy of Expression,' 1844, p. 190.

With respect to the upright position of the tail, it seems to depend
(but whether this is really the case I know not) on the elevator muscles
being more powerful than the depressors, so that when all the muscles of
the hinder part of the body are in a state of tension, the tail is raised.
A dog in cheerful spirits, and trotting before his master with high,
elastic steps, generally carries his tail aloft, though it is not held
nearly so stiffly as when he is angered. A horse when first turned
out into an open field, may be seen to trot with long elastic strides,
the head and tail being held high aloft. Even cows when they frisk
about from pleasure, throw up their tails in a ridiculous fashion.
So it is with various animals in the Zoological Gardens. The position of
the tail, however, in certain cases, is determined by special circumstances;
thus as soon as a horse breaks into a gallop, at full speed, he always
lowers his tail, so that as little resistance as possible may be offered
to the air.

When a dog is on the point of springing on his antagonist,
be utters a savage growl; the ears are pressed closely backwards,
and the upper lip (fig. 14) is retracted out of the way of his teeth,
especially of his canines. These movements may be observed with dogs
and puppies in their play. But if a dog gets really savage in his play,
his expression immediately changes. This, however, is simply due
to the lips and ears being drawn back with much greater energy.
If a dog only snarls at another, the lip is generally retracted
on one side alone, namely towards his enemy.

The movements of a dog whilst exhibiting affection towards his
master were described (figs. 6 and 8) in our second chapter.
These consist in the head and whole body being lowered and thrown into
flexuous movements, with the tail extended and wagged from side to side.
The ears fall down and are drawn somewhat backwards, which causes
the eyelids to be elongated, and alters the

{illust. caption = FIG. 14.--Head of snarling Dog. From life,
by Mr. Wood. whole appearance of the face.
The lips hang loosely, and the hair remains smooth.
All these movements or gestures are explicable, as I believe,
from their standing in complete antithesis to those naturally
assumed by a savage dog under a directly opposite state of mind.
When a man merely speaks to, or just notices, his dog,we see
the last vestige of these movements in a slight wag of the tail,
without any other movement of the body, and without even the ears
being lowered. Dogs also exhibit their affection by desiring
to rub against their masters, and to be rubbed or patted by them.
Gratiolet explains the above gestures of affection in the
following manner: and the reader can judge whether the explanation
appears satisfactory. Speaking of animals in general,
including the dog, he says,[2] "C'est toujours la partie la plus
sensible de leurs corps qui recherche les caresses ou les donne.
Lorsque toute la longueur des flancs et du corps est sensible,
l'animal serpente et rampe sous les caresses; et ces ondulations
se propageant le long des muscles analogues des segments jusqu'aux
extremites de la colonne vertebrale, la queue se ploie et s'agite."
Further on, he adds, that dogs, when feeling affectionate,
lower their ears in order to exclude all sounds, so that their whole
attention may be concentrated on the caresses of their master!
Dogs have another and striking way of exhibiting their affection,
namely, by licking the hands or faces of their masters.
They sometimes lick other dogs, and then it is always their chops.
I have also seen dogs licking cats with whom they were friends.
This habit probably originated in the females carefully licking
their puppies--the dearest object of their love--for the sake
of cleansing them. They also often give their puppies, after a
short absence, a few cursory licks, apparently from affection.
Thus the habit will have become associated with the emotion of love,
however it may afterwards be aroused. It is now so firmly
inherited or innate, That it is transmitted equally to both sexes.
A female terrier of mine lately had her puppies destroyed,
and though at all times a very affectionate creature,
I was much struck with the manner in which she then tried
to satisfy her instinctive maternal love by expending it on me;
and her desire to lick my hands rose to an insatiable passion.
[1] `De la Physionomie,' 1865, pp. 187, 218.The same principle
probably explains why dogs, when feeling affectionate, like rubbing
against their masters and being rubbed or patted by them, for from
the nursing of their puppies, contact with a beloved object has
become firmly associated in their minds with the emotion of love.
The feeling of affection of a dog towards his master is combined
with a strong sense of submission, which is akin to fear.
Hence dogs not only lower their bodies and crouch a little
as they approach their masters, but sometimes throw themselves
on the ground with their bellies upwards. This is a movement
as completely opposite as is possible to any show of resistance.
I formerly possessed a large dog who was not at all afraid
to fight with other dogs; but a wolf-like shepherd-dog
in the neighbourhood, though not ferocious and not so
powerful as my dog, had a strange influence over him.
When they met on the road, my dog used to run to meet him,
with his tail partly tucked in between his legs and hair not erected;
and then be would throw himself on the ground, belly upwards.
By this action he seemed to say more plainly than by words,
"Behold, I am your slave." A pleasurable and excited state
of mind, associated with affection, is exhibited by some
dogs in a very peculiar manner, namely, by grinning.
This was noticed long ago by Somerville, who says,
And with a courtly grin, the fawning bound Salutes thee
cow'ring, his wide op'ning nose Upward he curls, and his large
sloe-back eyes Melt in soft blandishments, and humble joy.'
_The Chase_, book i.Sir W. Scott's famous Scotch greyhound,
Maida, had this habit, and it is common with terriers.
I have also seen it in a Spitz and in a sheep-dog. Mr. Riviere,
who has particularly attended to this expression, informs me
that it is rarely displayed in a perfect manner, but is quite
common in a lesser degree. The upper lip during the act
of grinning is retracted, as in snarling, so that the canines
are exposed, and the ears are drawn backwards; but the general
appearance of the animal clearly shows that anger is not felt.
Sir C. Bell[3] remarks "Dogs, in their expression of fondness,
have a slight eversion of the lips, and grin and sniff
amidst their gambols, in a way that resembles laughter."
Some persons speak of the grin as a smile, but if it had been
really a smile, we should see a similar, though more pronounced,
movement of the lips and ears, when dogs utter their bark of joy;
but this is not the case, although a bark of joy often follows a grin.
On the other hand, dogs, when playing with their comrades
or masters, almost always pretend to bite each other; and they
then retract, though not energetically, their lips and ears.
Hence I suspect that there is a tendency in some dogs,
whenever they feel lively pleasure combined with affection,
to act through habit and association on the same muscles,
as in playfully biting each other, or their masters' hands.
I have described, in the second chapter, the gait and
appearance of a dog when cheerful, and the marked antithesis
presented by the same animal when dejected and disappointed,
with his head, ears, body, tail, and chops drooping, and eyes dull.
Under the expectation of any great pleasure, dogs bound and jump
about in an extravagant manner, and bark for joy. The tendency
to bark under this state of mind is inherited, or runs in the breed:
greyhounds rarely bark, whilst the Spitz-dog barks so incessantly
on starting for a walk with his master that he becomes a nuisance.
[1] `The Anatomy of Expression,' 1844, p. 140.An agony of pain is
expressed by dogs in nearly the same way as by many other animals,
namely, by howling writhing, and contortions of the whole body.
Attention is shown by the head being raised, with the ears erected,
and eyes intently directed towards the object or quarter
under observation. If it be a sound and the source is not known,
the head is often turned obliquely from side to side
in a most significant manner, apparently in order to judge
with more exactness from what point the sound proceeds.
But I have seen a dog greatly surprised at a new noise, turning,
his head to one side through habit, though he clearly perceived
the source of the noise. Dogs, as formerly remarked, when their
attention is in any way aroused, whilst watching some object,
or attending to some sound, often lift up one paw (fig. 4)
and keep it doubled up, as if to make a slow and stealthy approach.
A dog under extreme terror will throw himself down, howl, and void
his excretions; but the hair, I believe, does not become erect
unless some anger is felt. I have seen a dog much terrified
at a band of musicians who were playing loudly outside the house,
with every muscle of his body trembling, with his heart
palpitating so quickly that the beats could hardly be counted,
and panting for breath with widely open mouth, in the same manner
as a terrified man does. Yet this dog had not exerted himself;
he had only wandered slowly and restlessly about the room,
and the day was cold. Even a very slight degree of fear is
invariably shown by the tail being tucked in between the legs.
This tucking in of the fail is accompanied by the ears being
drawn backwards; but they are not pressed closely to the head,as
in snarling, and they are not lowered, as when a dog is pleased
or affectionate. When two young dogs chase each other in play,
the one that runs away always keeps his tail tucked inwards.
So it is when a dog, in the highest spirits, careers like a mad
creature round and round his master in circles, or in figures
of eight. He then acts as if another dog were chasing him.
This curious kind of play, which must be familiar to every one
who has attended to dogs, is particularly apt to be excited,
after the animal has been a little startled or frightened,
as by his master suddenly jumping out on him in the dusk.
In this case, as well as when two young dogs are chasing each
other in play, it appears as if the one that runs away was afraid
of the other catching him by the tail; but as far as I can
find out, dogs very rarely catch each other in this manner.
I asked a gentleman, who had kept foxhounds all his life,
and be applied to other experienced sportsmen, whether they
had ever seen hounds thus seize a fox; but they never had.
It appears that when a dog is chased, or when in danger
of being struck behind, or of anything falling on him, in all
these cases he wishes to withdraw as quickly as possible his
whole hind-quarters, and that from some sympathy or connection
between the muscles, the tail is then drawn closely inwards.
A similarly connected movement between the hind- quarters and
the tail may be observed in the hyaena. Mr. Bartlett informs
me that when two of these animals fight together, they are
mutually conscious of the wonderful power of each other's jaws,
and are extremely cautious. They well know that if one of their
legs were seized, the bone would instantly be crushed into atoms;
hence they approach each other kneeling, with their legs turned
as much as possible inwards, and with their whole bodies bowed,
so as not to present any salient point; thetail at the same time
being closely tucked in between the legs. In this attitude
they approach each other sideways, or even partly backwards.
So again with deer, several of the species, when savage and fighting,
tuck in their tails. When one horse in a field tries to bite
the hind-quarters of another in play, or when a rough boy
strikes a donkey from behind, the hind-quarters and the tail
are drawn in, though it does not appear as if this were done
merely to save the tail from being injured. We have also seen
the reverse of these movements; for when an animal trots with
high elastic steps, the tail is almost always carried aloft.
As I have said, when a dog is chased and runs away, he keeps
his ears directed backwards but still open; and this is clearly
done for the sake of hearing the footsteps of his pursuer.
From habit the ears are often held in this same position,
and the tail tucked in, when the danger is obviously in front.
I have repeatedly noticed, with a timid terrier of mine,
that when she is afraid of some object in front, the nature
of which she perfectly knows and does not need to reconnoitre,
yet she will for a long time hold her ears and tail in this position,
looking the image of discomfort. Discomfort, without any fear,
is similarly expressed: thus, one day I went out of doors, just at
the time when this same dog knew that her dinner would be brought.
I did not call her, but she wished much to accompany me,
and at the same time she wished much for her dinner;
and there she stood, first looking one way and then
the other, with her tail tucked in and ears drawn back,
presenting an unmistakable appearance of perplexed discomfort.
Almost all the expressive movements now described, with the
exception of the grinning from joy, are innate or instinctive,
for they are common to all the individuals, young and old,
of all the breeds. Most of themare likewise common to the
aboriginal parents of the dog, namely the wolf and jackal;
and some of them to other species of the same group.
Tamed wolves and jackals, when caressed by their masters,
jump about for joy, wag their tails, lower their ears,
lick their master's hands, crouch down, and even throw themselves
on the ground belly upwards.[4] I have seen a rather fox-like
African jackal, from the Gaboon, depress its ears when caressed.
Wolves and jackals, when frightened, certainly tuck in their tails;
and a tamed jackal has been described as careering round
his master in circles and figures of eight, like a dog,
with his tail between his legs. It has been stated[5] that foxes,
however tame, never display any of the above expressive movements;
but this is not strictly accurate. Many years ago I observed
in the Zoological Gardens, and recorded the fact at the time,
that a very tame English fox, When caressed by the keeper,
wagged its tail, depressed its ears, and then threw itself
on the ground, belly upwards. The black fox of North America
likewise depressed its ears in a slight degree. But I believe
that foxes never lick the hands of their masters, and I have been
assured that when frightened they never tuck in their tails.
If the explanation which I have given of the expression of affection
in dogs be admitted, then it would appear that animals which have
never been domesticated--namely wolves, jackals, and even foxes--
have nevertheless ac- quired, through the principle of antithesis,
certain expressive gestures; for it is Dot probable that these animals,
confined in cages, should have learnt them by imitating dogs.
[4] Many particulars are given by Gueldenstadt in his account
of the jackal in Nov. Comm. Acad. Sc. Imp. Petrop.
1775, tom. xx. p. 449. See also another excellent account
of the manners of this animal and of its play, in `Land
and Water,' October, 1869. Lieut. Annesley, R. A., has also
communicated to me some particulars with respect to the jackal.
I have made many inquiries about wolves and jackals in
the Zoological Gardens, and have observed them for myself.
[5] `Land and Water,' November 6, 1869._Cats_.--I have already
described the actions of a cat

(fig. 9), when feeling savage and not terrified.
She assumes a crouching attitude and occasionally protrudes
her fore-feet, with the claws exserted ready for striking.
The tail is extended, being curled or lashed from side to side.
The hair is not erected--at least it was not so in the few
cases observed by me. The ears are drawn closely backwards
and the teeth are shown. Low savage growls are uttered.
We can understand why the attitude assumed by a cat when preparing
to fight with another cat, or in any way greatly irritated,
is so widely different from that of a dog approaching another dog
with hostile intentions; for the cat uses her fore-feet for striking,
and this renders a crouching position convenient or necessary.
She is also much more accustomed than a dog to lie concealed
and suddenly spring on her prey. No cause can be assigned with
certainty for the tail being lashed or curled from side to side.
This habit is common to many other animals--for instance,
to the puma, when prepared to spring;[1] but it is not
common to dogs, or to foxes, as I infer from Mr. St. John's
account of a fox lying in wait and seizing a hare.
We have already seen that some kinds of lizards and various snakes,
when excited, rapidly vibrate the tips of their tails.
It would appear as if, under strong excitement, there existed
an uncontrollable desire for movement of some kind, owing to
nerve-force being freely liberated from the excited sensorium;
and that as the tail is left free, and as its movement does
not disturb the general position of the body, it is curled
or lashed about.

All the movements of a cat, when feeling affectionate, are in complete
antithesis to those just described. She now stands upright,
with slightly arched back, tail perpendicularly raised, and ears erected;
and she rubs her cheeks and flanks against her master or mistress.
The desire to rub something is so strong in cats under this state of mind,
that they may often be seen rubbing themselves against the legs
of chairs or tables, or against door-posts. This manner of expressing
affection probably originated through association, as in the case
of dogs, from the mother nursing and fondling her young; and perhaps
from the young themselves loving each other and playing together.
Another and very different gesture, expressive of pleasure, has already
been described, namely, the curious manner in which young and even
old cats, when pleased, alternately protrude their fore-feet, with
separated toes, as if pushing against and sucking their mother's teats.
This habit is so far analogous to that of rubbing against something,
that both apparently are derived from actions performed during
the nursing period. Why cats should show affection by rubbing
so much more than do dogs, though the latter delight in contact
with their masters, and why cats only occasionally lick the hands
of their friends, whilst dogs always do so, I cannot say. Cats cleanse
themselves by licking their own coats more regularly than do dogs.
On the other hand, their tongues seem less well fitted for the work
than the longer and more flexible tongues of dogs.

[1] Azara, `Quadrupedes du Paraquay,' 1801, tom. 1. p. 136.

Cats, when terrified, stand at full height, and arch their backs
in a well-known and ridiculous fashion. They spit, hiss, or growl.
The hair over the whole body, and especially on the tail, becomes erect.
In the instances observed by me the basal part of the tail was held upright,
the terminal part being thrown on one side; but sometimes the tail (see fig.
15) is only a little raised, and is bent almost from the base to one side.
The ears are drawn back, and the teeth exposed. When two kittens
are playing together, the one often thus tries to frighten the other.
From what we have seen in former chapters, all the above points of
expression are intelligible, except the extreme arching of the back.
I am inclined to believe that, in the same manner as many birds,
whilst they ruffle their feathers, spread out their wings and tail,
to make themselves look as big as possible, so cats stand upright at their
full height, arch their backs, often raise the basal part of the tail,
and erect their hair, for the same purpose. The lynx, when attacked,
is said to arch its back, and is thus figured by Brehm. But the keepers
in the Zoological Gardens have never seen any tendency to this action
in the larger feline animals, such as tigers, lions, &c.; and these have
little cause to be afraid of any other animal.

Cats use their voices much as a means of expression, and they utter,
under various emotions and desires, at least six or seven
different sounds. The purr of satisfaction, which is made during
both inspiration and expiration, is one of the most curious.
The puma, cheetah, and ocelot likewise purr; but the tiger, when pleased,
"emits a peculiar short snuffle, accompanied by the closure
of the eyelids."[7] It is said that the lion, jaguar, and leopard,
do not purr.

_Horses_.--Horses when savage draw their ears closely back,
protrude their heads, and partially uncover their incisor teeth,
ready for biting. When inclined to kick behind, they generally,
through habit, draw back their ears; and their eyes are
turned backwards in a peculiar manner.[8] When pleased,
as when some coveted food is brought to them in the stable,
they raise and draw in their heads, prick their ears,
and looking intently towards their friend, often whinny.
Impatience is expressed by pawing the ground.

[7] `Land and Water,' 1867, p. 657. See also Azara on the Puma,
in the work above quoted.

[8] Sir C. Bell, `Anatomy of Expression,' 3rd edit. p. 123. See also p.
126, on horses not breathing through their mouths, with reference
to their distended nostrils.

The actions of a horse when much startled are highly expressive.
One day my horse was much frightened at a drilling machine,
covered by a tarpaulin, and lying on an open field. He raised
his head so high, that his neck became almost perpendicular;
and this he did from habit, for the machine lay on a slope below,
and could not have been seen with more distinctness through
the raising of the head; nor if any sound had proceeded
from it, could the sound have been more distinctly heard.
His eyes and ears were directed intently forwards; and I
could feel through the saddle the palpitations of his heart.
With red dilated nostrils he snorted violently, and whirling round,
would have dashed off at full speed, had I not prevented him.
The distension of the nostrils is not for the sake of scenting
the source of danger, for when a horse smells carefully at any
object and is not alarmed, he does not dilate his nostrils.
Owing to the presence of a valve in the throat, a horse when
panting does not breathe through his open mouth, but through
his nostrils; and these consequently have become endowed with
great powers of expansion. This expansion of the nostrils,
as well as the snorting, and the palpitations of the heart,
are actions which have become firmly associated during a long
series of generations with the emotion of terror; for terror
has habitually led the horse to the most violent exertion
in dashing away at full speed from the cause of danger.

_Ruminants_.--Cattle and sheep are remarkable from displaying in so slight
a degree their emotions or sensations, excepting that of extreme pain.
A bull when enraged exhibits his rage only by the manner in which be
holds his lowered head, with distended nostrils, and by bellowing.
He also often paws the ground; but this pawing seems quite different
from that of an impatient horse, for when the soil is loose, he throws up
clouds of dust. I believe that bulls act in this manner when irritated
by flies, for the sake of driving them away. The wilder breeds of sheep
and the chamois when startled stamp on the ground, and whistle through
their noses; and this serves as a danger-signal to their comrades.
The musk-ox of the Arctic regions, when encountered, likewise stamps
on the ground.[9] How this stamping action arose I cannot conjecture;
for from inquiries which I have made it does not appear that any of
these animals fight with their fore-legs.

Some species of deer, when savage, display far more expression
than do cattle, sheep, or goats, for, as has already been stated,
they draw back their ears, grind their teeth, erect their hair,
squeal, stamp on the ground, and brandish their horns.
One day in the Zoological Gardens, the Formosan deer
(_Cervus pseudaxis_) approached me in a curious attitude,
with his muzzle raised high up, so that the horns were pressed
back on his neck; the head being held rather obliquely.
From the expression of his eye I felt sure that he was savage;
he approached slowly, and as soon as he came close to the iron bars,
he did not lower his head to butt at me, but suddenly bent it inwards,
and struck his horns with great force against the railings.
Mr. Bartlett informs me that some other species of deer place
themselves in the same attitude when enraged.

_Monkeys_.--The various species and genera of monkeys express
their feelings in many different ways; and this fact is interesting,
as in some degree bearing on the question, whether the so-called races
of man should be ranked as distinct species or varieties; for, as we
shall see in the following chapters, the different races of man express
their emotions and sensations with remarkable uniformity throughout
the world. Some of the expressive actions of monkeys are interesting
in another way, namely from being closely analogous to those of man.
As I have had no opportunity of observing any one species of the group
under all circumstances, my miscellaneous remarks will be best arranged
under different states of the mind.

[9] `Land and Water,' 1869, p. 152.

_Pleasure, joy, affection_--It is not possible to distinguish
in monkeys, at least without more experience than I have had,
the expression of pleasure or joy from that of affection.
Young chimpanzees make a kind of barking noise, when pleased
by the return of any one to whom they are attached.

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