THE MAN-SHAPED APES (_concluded_)--THE GIBBONS[18]--1. THE SIAMANGS--2.
THE TRUE GIBBONS.
General Characteristics of the Species--THE SIAMANG--Its Habits
and Anatomy--Distinctness from the Orangs and Gibbons--Special
Peculiarities--THE WHITE-HANDED GIBBON--Where Found--Its Cry--Its
Habits--Special Anatomical Features--THE HOOLOOK--Where Found--A
Young One in Captivity--Shape of the Skull--THE WOOYEN APE--Its
Appearance and Habits--THE WOW-WOW--Very little Known about
it--THE AGILE GIBBON--Reason of the Name--Peculiarities of the
Anatomy--General Comparison of the Different Varieties of the Great
Apes.
The Orang-utan is not the only man-shaped Ape of the forests and
jungles of the great Asiatic Islands, for there are several others to
be found there, and which also live on the main land, from Malacca far
away to the north in Assam; southwards, in the peninsula of Hindostan,
and in South China.
They are less human-looking than the red Orangs, and they are smaller
and more slender, but when they walk for a short distance erect, with
the arms above the head balancing the body, their resemblance to a
small and hairy “lord of creation” is considerable. A very slight
glance distinguishes them from the Orangs; they have straight backs,
small beads, large eyes, rather prominent chins, very long fore-arms,
and their fingers reach the ankle in some, and the ground in others.
Moreover, the Orangs sit upon a surface of hair, and these are
furnished with a hard pad-like seat which is bare, and is called a
callosity, but they have no tail. They can run.
These long-armed Apes have a number of names, but as a whole they
are called Gibbons; and as their outside and inside differences and
distinctions from the Orangs are considerable and more than those
of the kinds of Orangs between themselves, they are grouped into a
separate genus. The Orangs form, as has been stated before, the genus
_Simia_, and these Gibbons constitute the genus _Hylobates_, a term
taken from the Greek ὑλοβάτης, a walker in the woods.
So far as their intelligence, amiability, and teachableness are
concerned, they are equal to the Orangs, and indeed they seem to adapt
themselves to the methods of men more readily. Not only do they become
very fond of their keepers, but they recollect them after the lapse of
time; and they are constantly let loose by those who keep them in India
to wander about the trees in the neighbourhood, and they will return to
be cared for, and come, when called, to be fed.
Interesting to those who study the intelligence of animals, they are
equally so to the common observer, who delights in witnessing their
surpassing agility, wonderful leaps, and graceful swings from bough
to bough. But to the anatomist they present many complicated problems
for although evidently not so high in the animal scale as the Orangs
and Chimpanzees, they have some things about them which cause them to
resemble man more than do these great Apes, and others which cause
them to resemble the large army of Monkeys. They are the last of the
man-shaped in the classification, and the usual plan is to place them
after the Orangs.
They are extremely delicate animals, although their fur is thick,
and, in some kinds, long. They require a considerable temperature and
very pure air; hence, although many have been brought to Europe, and
exhibited to the delight of thousands, they do not live long, dying
usually from consumption or from some lung disease. In the British
Museum there are several groups of stuffed specimens of them, and also
many skulls and skeletons, and a cursory examination of the first
will prove that it is very difficult to distinguish one kind from
another, for in the same kind, or species, there is a great variety of
colour, and a different individuality in the two sexes and young. It
has happened that the same kind has been called by several names by
different observers, and it is only when the skeleton has been examined
with the stuffed specimen that a satisfactory distinction between the
species or kinds has been made.
Evidently, the whole of these long-armed Apes, with small heads and
callosities on the seat, are separable into two divisions. In one the
animals are larger than the others, and have a very singular adaptation
of the foot for rapid movement amongst the boughs, and they have
air-pouches; and in the second the animals are smaller, and have the
toes free, and have no pouches. So the genus _Hylobates_ is divided
into two divisions: 1. The Siamangs. 2. The True Gibbons.
THE SIAMANG.[19]
Sir Stamford Raffles brought the Siamang prominently before the
scientific world, and noticed the curious manner in which some of the
toes were united, and he considered that this was to enable them to
swing rapidly from branch to branch during their ordinary movements
in the forest, when any stretching out of the fingers might be
dangerous and produce a fall. But in this, as in many others, we owe
to Mr. Wallace thanks for a concise description of the habits of the
creature, which, from having its toes partly joined, has been named,
_Syndactylus_, from the Greek words σὺν and δάκτυλος, which mean
“together” and “finger.”
“A very curious Ape, the Siamang, was rather abundant, but it is much
less bold than the common Monkeys, keeping to the virgin forest, and
avoiding villages. This species is allied to the little long-armed
Apes of the genus _Hylobates_, but is considerably larger, and differs
from them by having the two first fingers of the feet united together,
nearly to the end; whence its name. It moves much more slowly than the
_Hylobates_, keeping lower down in the trees, and not indulging in such
tremendous leaps; but still it is very active, and by means of its
immense long arms--five feet six inches across in an adult about three
feet high--can swing itself along among the trees at a great rate. I
purchased a small one, which had been caught by the natives, and tied
up so tightly as to hurt it. It was rather savage at first, and tried
to bite, but when we had released it, and given it two poles under
the verandah to hang upon, securing it by a short cord running along
the pole with a ring, so that it could move easily, it became more
contented, and would swing itself about with greater rapidity. It ate
almost any kind of fruit and rice, and I was in hopes to have brought
it to England, but it died just before I started. It took a dislike
to me at first, which I tried to get over by feeding it constantly
myself. One day, however, it bit me so sharply while giving it food
that I lost patience, and gave it rather a severe beating which I
regretted afterwards, as from that time it disliked me more than ever.
It would allow my Malay boys to play with it, and for hours together
would swing by its arms from pole to pole, and on to the rafters of the
verandah, with so much ease and rapidity, that it was a constant source
of amusement to us. When I returned to Singapore it attracted great
attention, as no one had seen a Siamang before, although it is not
uncommon in some parts of the Malay peninsula.”
There are some interesting points about the relation of the
construction of this animal and its method of moving. Thus, in
grasping a bough with the arm at full length above the head, so as
to leave it with a swing in order to grasp another rapidly and for
a correspondingly short period of time, the fingers require to be
kept together as much as is possible, and to remain more or less bent
on the palm. The long thumb may or may not be used, but in order to
move efficiently it must be free, and also strong. Now in the Siamang
these necessary peculiarities are present, and the common use of the
finger and thumb in taking hold of things in the ordinary manner is
sacrificed to them, and there is little or no delicacy of fingering or
of prehension. Moreover, the fingers and thumbs are extremely thin and
delicate, and in order to render the first finger less movable, it is,
to a certain extent, deficient in its muscles of extension; and the
common bending or flexor muscle of the fingers is very independent of
that of the thumb. In compensation there is a special muscle found in
this genus alone, which pulls the top of the second finger towards the
thumb.[20] The skeleton of the hand shows that the fingers are slightly
curved. There is no doubt that the hand of the Siamang, although it has
these peculiar muscles, the curve of the bones, and also the extra bone
noticed in the Orangs, is, as far as its skeleton is concerned, much
more human than that of the other Apes. The extensor muscles of the
fingers resemble those of the Orangs. The hand is larger than the foot
in these animals, and the forearm is much longer than the upper arm.
A French naturalist states that the animal can leap, or, rather,
swing--for it is done with the fore limbs--with graceful agility at
least eighty feet, and the muscles of the arm, which are connected with
the chest, aid in this. The pull is from the stationary arm to the
chest of the movable body by muscular contraction; and the greater the
muscular connection between the arm and chest, the greater will be the
movement. In order to provide for this, the great muscle of the front
of the upper arm, the biceps (see page 26), is not only attached, as in
the other Apes and in man, to the blade-bone just above the arm-joint,
but also to the chest in front, for it is united there with the great
muscle which springs from the ribs and breast-bone, and is attached
high up to the arm (_pectoralis major_). In some of the other Apes this
second part of the biceps is attached to a bent projection (coracoid)
of the blade-bone, so that it has no direct attachment with the chest
itself.
The Siamang can walk fairly in the erect posture by balancing with
the arms, or by placing them over the head, and it has a great power
of grasp with its toe-thumb. The shape of the foot resembles that of
man more than that of the Troglodytes and Orangs, and the heel-bone is
strong, and projects but slightly, and the toe-thumb is stout and long.
The muscles of the foot are, as it were, more separate than in man,
especially the flexors: and there is an extra muscle, an abductor of
the third joint of the second toe.
The ability to walk well was proved when a tame Siamang used to walk
along a cabin table at sea, without disturbing the crockery; and
curiously enough this was better done than were some of the ordinary
movements of the hand, for drinking out of the palm was a most
ineffective and clumsy effort.
The bones of the foot resemble those of man more than do those of the
Apes already noticed; but the first and second fingers are united by a
fold of skin.
Under the jaw and along the throat of a tame Siamang, a large swelling,
not very well covered with hair, was visible enough. This was a vast
air or laryngeal pouch, and pressure emptied it into the throat. Hence
the creature in this point resembles the Oranges and the Troglodytes,
but the use of the sac could not be satisfactorily decided. The sac
opens into the windpipe by two apertures, which are in a membrane that
unites the base of the tongue and the organ of voice together. It has
an uvula.
They are quiet, inoffensive animals, full of affection for man,
and having good memories. Their temper is short enough sometimes,
especially if there is any disappointment, but they have none of the
mischievous tricks or malice of the Monkeys. Liking milk occasionally,
they still mainly feed on fruit and leaves, and hence the nature of
their teeth, the size of their jaws, and the capacity of their brain
case may be fairly anticipated.
The bulk of the brain is less in comparison with that of the Orang,
and the hind part does not quite cover or overlap the cerebellum, and
the whole skull is long and low, and slightly broad behind. The most
striking parts about it are the cavities for the eyes (the orbits),
which are nearly circular in outline, deep, open, and swollen behind;
moreover, they are wide apart, and there is no brow ridge connecting
them. They, the face and the lower jaw, occupy only one-half of the
skull, and the brain case is composed of the usual bones, which are
extremely faintly ridged, the ridges extending on either side from the
outer part of the orbit on to the frontal and parietal (or side) head
bones. The back of the skull is rough, for the attachment of muscles,
and the opening for the spinal cord and the joints for the top of the
neck are far back, so that the head is set, as it were, forward in
respect of the spine. There is a long and narrow roof to the mouth,
and the diastema, or space in the line of the teeth, in front of the
upper eye or canine teeth, is very distinct. These teeth are long,
thin, and grooved, and project rather outwards as well as far below the
other upper teeth. Yet, in all probability, this is not a bloodthirsty
sign, but one which may have to do with sex, the males of many of
the Monkeys possessing these great teeth only, or having them larger
than the females. The first, or incisor teeth, occupy a very small
space, and they and the two front molars are like those of man. An
examination of the three true crushing molars shows the last, or that
nearest the back of the jaw, to be the largest. They have four cusps or
projections, which are small but decided, and somewhat resemble those
of insect-eating animals.
The lower jaw is very remarkable, for it has a good straight chin; and
the joint and the part which passes from it to the body of the jaw, or
the “angle,” resembles that of man more than that of the rest of the
Apes.
The lower teeth are very unlike the upper, and the canines are smaller;
the first false molar is pyramidal, and has a cutting surface in front
and behind. The true molars have at least five cusps or projections,
and are admirably suited for the creature’s diet.
[Illustration: SKELETON OF THE SIAMANG.
(_From the “Cyclopædia of Anatomy and Physiology.”_)]
One of the most curious points about the Siamang is that the broad
breast-bone, the blade-bone, and large chest, and the ribs present
human resemblances, but there are fourteen pairs of these last. The
hip-bones are long and do not curve far in front, but the joint of the
thigh is situated more after the manner of that of man than is the case
in the other great Apes.
Everything in this creature’s anatomy, and, amongst other things, its
delicate, long bones, great grasp, supple back, small head, long neck,
and long hair, assist in its peculiar life, which is evidently one of
much climbing, swaying, swinging, and passing from tree to tree with
the hands rather than with the feet. It lives in Sumatra and in the
Malay peninsula.
THE TRUE GIBBONS.
The other kinds of Hylobates are called the True Gibbons, and although
in their habits they greatly resemble the Siamang, they are smaller
in size, and have some very remarkable structural differences.
They inhabit the mainland of India and the great islands of Borneo
and Sumatra, or, rather, all the great islands of the Indo-Malayan
sub-region, except the Philippines. They are found in Sylhet, and
Assam, and Camboja, in South China, to the west of Canton, and in the
island of Hainan.
[Illustration: GROUP OF SIAMANGS AND GIBBONS.]
THE WHITE-HANDED OR LAR GIBBON.[21]
A well-known kind of Gibbon, which is found in Tenasserim, is called
the White-handed Gibbon, or _Hylobates lar_. The old Latin dictionaries
translated “lar” as a god who preserved both house and land, and
presided over cities and houses, or the chimney or fireside; but this
evidently does not apply to the Gibbon. But the Lar, or Lares, were
demons, genii, or sprites, and probably the sprite-like activity of the
Gibbons in their own woods suggested the name.
[Illustration: WHITE-HANDED GIBBON. (_From a stuffed specimen._)]
The Hylobates Lar is found in great abundance in all the forests
skirting the hills, which run from north to south in the country of
Tenasserim, south-west of Burmah. They ascend the hills up to an
elevation of from 3,000 to 3,500 feet, but not higher, and are met with
in parties of from eight to twenty in number, composed of individuals
of all ages. It is rare to see a solitary one; occasionally, however,
an old male will stray apart from the flock, and perch on the summit
of some vast tree, whence his howls are heard for miles around. The
forests which these animals inhabit resound with their cries from
sunrise to about nine in the morning, and their usual call may be thus
rendered:--
[Illustration: Woo, a-woo, a-woo, a-wow--------o-o woo.]
The sounds vary from the deep notes of the old ones to the sharp
treble of the young, in horrible unison. During these vocal efforts
they appear to resort to the tops of the loftiest trees, and to
call each other from different parts of the jungle. After nine or
ten o’clock they begin to think of eating, and are soon engaged in
feeding on fruit, young leaves, buds, shoots, and insects, for which
they occasionally come to the ground. When approached, if alone, they
will sit so close, doubled up in a thick tuft of foliage, or behind
the fork of a tree, and so screened as to be safe from the shot of
the sportsman. With a companion this manœuvre is of course useless.
But even when the creature is forced from its hiding-place it is not
easily shot, for it swings from branch to branch with its long arms,
shaking the boughs all round, and flinging itself from prodigious
heights into the dense under-scrub, and is quickly concealed from view.
This long-armed Ape does not walk readily on its hind-legs, and has to
stop frequently and prop or urge itself on, having the knuckles on the
ground. In sitting it often rests on its elbows, and it likes to lie on
its back. They make great use of their hind limbs, and of the hand-foot
especially, for they will cling on and swing with their fore-hands, and
steal and carry anything which pleases them with their hinder ones. In
captivity it is generally a gentle, peaceable animal, very timid; but
when captured after its young days have passed, it becomes very wild.
The adults soon die, and even the young seldom reach maturity when
deprived of liberty. They are born generally in the early part of the
cold weather, a single one at a time, two being as rare as human twins.
The young one clings safely to the mother for about seven months,
although she swings and climbs to perfection, and then it shifts for
itself. They may be made cross, like most creatures, by being teased,
and anger is then shown by a steady look, with the mouth held open, and
the lips occasionally drawn back to show the eye teeth, with which they
bite severely. But usually it attacks with its long hands, which are
at such times held dangling and shaken in a ridiculous manner, like a
person who has suddenly burnt his fingers. It drinks in a curious and
difficult manner, by scooping the water in its long narrow hand, and
thus conveying a very little drop at a time to its mouth.
Usually the young are feeble, dull, and querulous in captivity, and
sit huddled up together on the ground, seldom or never climbing trees.
On the smooth surface of a matted floor they will run along on their
feet and slide on their hands at the same time. By being fed solely
on plantains, or on milk and rice, they are apt to lose all their
fur, presenting in their nude state a most ridiculous appearance. Few
recover; but by change of diet, and especially by allowing them to
help themselves to insects, some of them come round, and resume their
natural covering. For the most part they are devoid of those pranks
and tricks which are exhibited by the smaller Monkeys. The length of
a full-grown male was two feet six inches; the fore-limb measured two
feet one inch, and the hind limb one foot seven and a half inches. The
Lar or White-handed Gibbon has a black skin and hair, and there is a
white band round the entire face, across the forehead.
The Lar is common in its native haunts, and is subject to great
variation in its colour. Some are dark brown or black, with white hands
and feet, and they have the circle of white hairs around the face, the
band across the forehead coming down in a peak above the nose. Others
are ochre-brown, and have a lighter-coloured hand, foot, and anklet;
whilst many are a dirty white. They take odd fancies, and likes and
dislikes. Some which are allowed in India to roam about the grounds of
the Zoological Gardens there will come in to sleep, and are exceedingly
gentle to men, but extremely savage to women; others do not do this.
In looking at the collection in the British Museum, every one must
be struck with the long necks of these creatures, which do not allow
the little muzzle and snub-like nose to come down on a level with the
breast-bone (as in the Chimpanzee, for instance), and also with the
extremely narrow and long hands and feet, with their thin fingers. It
will be also noticed that the nails of their thumbs and toe-thumbs are
flat, whilst all the rest are claws. Their chin is less prominent than
that of the Siamang, and this is shown in the skull. In the lower jaw
there are some interesting differences between the Lar and the Siamang
which cannot readily be accounted for; firstly, the crushing teeth wear
in pits in the middle, whilst a ridge is formed in the Siamang; and in
the Lar the angle of the jaw is decidedly turned in or inflected, as
the term is, a condition which will be noticed in the other Hylobates.
No air or laryngeal sac is found in the Lar or in any Gibbon, and its
noise has therefore nothing to do with such an organ.
Their swinging from branch to branch is assisted by the same
arrangement of the muscle of the arm as in the Siamang; and they have
the _transversus pedis_, which was stated to be wanting in the Orang,
and it is united with the adductor of the thumb.
THE HOOLOOK.[22]
Naturalists have ransacked nearly every part of the globe for
interesting animals, and have procured them from very out-of-the-way
places. One of these localities was particularly difficult to get
at years ago, for it is in the hills, far away to the north-east of
Calcutta the other side of the great river Brahmapootra, in Assam.
Amongst the Garrow and Cossyah hills, where there are wild gorges, and
uplands crowded with vast forests, overlooking the wide plains of the
river-valley, there were many wonderfully active Gibbons. About two
feet in length, they were capable of swinging with unerring certainty
from branch to branch, many feet apart; and even the females performed
these constant and natural movements while their young were hanging to
them. They were black in colour, with white eyebrows, or, rather, a
white band across the forehead. When caught, they soon became tamed,
especially when young, and were docile and affectionate. One which
was kept by Dr. Burrough was two feet six inches in length, yet the
fore-limb was only five inches shorter than this, the length of the
hand itself being six inches.
[Illustration: SKULL OF HOOLOOK.]
So great was the disproportion of the legs and arms, that the first
were, including the feet, only nineteen inches long, and the fingers
touched the ground readily when he was standing erect. This Hoolook
was of a deep black colour, and he had the usual simple band of white
across the forehead, and black hands and feet. He was caught in the
usual haunt of this species, not on the upper, but on the lower hills,
which do not reach a greater altitude than 500 feet, and being well
treated, he was easily tamed, and his habits were capable of being well
watched. He liked the fruit of the peepul-tree better than anything,
and bananas; but he took to rice and milk, and enjoyed snapping up a
sweet or two, and especially delighted in Spiders. Meat he cared little
about, and pork and beef he detested, but he liked fish occasionally.
After about a month’s captivity he took a great fancy to his master,
and would come to his call, and sit up to breakfast. He liked to help
himself to chicken and egg, and at first was very bad in his manners,
dipping his fingers into the coffee and milk, and then sucking them.
Afterwards he was taught to hold a cup and to drink from it.
He would walk erect slowly, first on one foot and then on the other,
and would put his long arms over his head to balance his body, as it
swayed first on one side and then on the other as his pace increased;
then he began to run, and at last, grasping a bough, would swing
himself forwards first with one hand and then with the other, getting
over twenty to thirty paces with the greatest ease and regularity.
He was timid, very reluctant to oppose those who teased him, and
usually retreated at once. His master used to brush his skin for him
when he was out of sorts, and the sensation appears to have been most
pleasurable, and he evidently enjoyed the gentle friction very much.
Falling ill he had a dose of calomel and a warm bath, the latter remedy
being much more to his taste than the other.
The skull in the Hoolook has less breadth across the orbits than in
the Lar; and in that of a young one the sutures or joinings of the
skull-bones are distinct, showing that the side-bones (parietal) of the
head unite with the front (frontals), the temporal or ear-bones, and
with a part of a wing-shaped bone which forms part of the base of the
skull (sphenoid bone). The angle of the jaw projects backwards, and
it is slightly turned in; moreover, the projections or cusps of the
lower back teeth are five in number, and are prominent-looking and very
sharp, as if they could crush a beetle as well as crack a nut.
THE WOOYEN APE, OR YUEN.[23]
A number of Apes were found in company on a small island near
Camboja, and at first sight they appeared to be of different kinds,
although they all had the long arms and the general appearance of
the “Long-armed Apes” (_Hylobates_). But a careful examination proved
that they belonged to one particular species, the individuals of which
differ greatly in their colour during different parts of their lives.
The young were uniformly dirty white in colour, and had no black spots
on their chests or heads. The females were white, with the fur of the
back brownish-white, slightly waved, and there was a large black spot
on the crown and one on the chest. On the other hand the male was
black, and the back of the head, body, and legs greyish. The hands were
white. This variation in colour at different ages and in different
sexes in one kind should teach us that something more than mere outside
distinctions is requisite for deciding the value of what are called
species. The dark cap-like mass of hair on the head gives the name
to this Ape. Evidently the animal is a puzzle and a source of the
marvellous to the Chinese, for one of their gazetteers gives a mixture
of correct information regarding its natural history, and of what has
been drawn from a very vigorous imagination.
[Illustration: HOOLOOK. (_From a stuffed specimen in the British
Museum._)]
It is described in the following manner, as coming from the district of
Hainan:--“Yuen--male black, female white, like a Macaque, but larger,
with the two fore-arms exceedingly long. Climbs to tree-tops, and runs
among them backwards and forwards with great agility. If it falls to
the ground it remains there like a log! Its delight is in scaling
trees, as it cannot walk on the ground. Those desiring to rear it in
confinement should keep it amongst trees, for the exhalations of the
earth affect it with diarrhœa, causing death; a sure remedy for this,
however, may be found in a draught made of the syrup of the fried
foo-tse” (seeds of _Abrus precatorius_, the Indian liquorice).
In a work called _Pun Yu liang che_, the various kinds of Yuens are
mentioned which are known to the author. “There are three kinds of
Yuens--the Golden-silk Yuen, which is yellow; the Jade-faced Yuen,
which is black; and the Jet-black Yuen, which has the face also black.
The Golden-silk and the Jade-face are both difficult to procure.”
“Hainan has also the Rock Yuen; it is small, about the size of one’s
fist. If allowed to drink water it grows in size. This is also called
the Black Yuen, and is difficult to obtain.” “The word Yuen is given
to them from their love of climbing and their wild disposition.”
In Central Hainan the magistrate of the district was of opinion that
the Yuen had the power of drawing its long arm-bones into its body,
and that when it drew in one it pushed out the other to such an
extraordinary length that he believed the two bones united in the body.
He used the front bones of the arms for chopsticks.
THE WOW-WOW.
A species which is called the Wow-wow, or Silvery Gibbon (_Hylobates
leuciscus_), is perhaps more interesting to the anatomist than to the
observer of the habits of animals; for nothing is known about their
method of living. Their skull shows a decided ridge or crest along the
top, which branches well in front into two ridges going to the front
over the orbit. Moreover, the chin of the lower jaw is very deep, the
angles slightly turned in, and the eye teeth are thin and sharp.
[Illustration: WOOYEN APE. (_From a stuffed specimen in the British
Museum._)]
THE AGILE GIBBON.[24]
This animal is also interesting, from having a great twist inwards of
the jaw behind, and two curious ridge-like crests on the head. Its name
conveys the extreme agility of the animal, as observed in confinement.
These Gibbons have many interesting points about them, and one of the
most curious is that they have no air or laryngeal pouches, and yet
their general anatomy, especially of the muscles of the throat, neck,
and body, is the same as that of the Siamang, which has been noticed
above to have a vast pouch. The brain is small, especially behind, but
why it is difficult to imagine, for the Spider Monkey, which lives
in the New World, and whose feats of agility resemble those of the
Gibbons, has a very large back portion of the brain, large even in
proportion to that of man; and the importance of this difference is
all the greater when it is remembered that all the last investigations
into the actions of the nerves arising from the sides of the brain
towards the back connect them with motions of the hands and fore-limbs
especially. But it is possible that the back of the brain in the
Siamang appears to be smaller than it really is, because of the large
size of the cerebellum. The skulls of the Gibbons are very man-like,
and more so than those of the other Apes, and this is because of their
faces and jaws being smaller in comparison with the brain case. If the
young of all the great Apes be examined, their skulls will appear much
more human than those of the adults, because the brain and face grow up
to a certain point together and equally; but with age the brain does
not increase in size proportionally with the face, which grows on, and
finally preponderates in size. But if the skulls of the young Apes be
compared one with the other, that of the Siamang will really not look
as human as that of the Gorilla or Chimpanzee.
[Illustration: AGILE GIBBON.]
The Gibbons have a very small appendage to the blindgut, and they have
hard bare pads or callosities on the seat, and these structures connect
them with the next group of Monkeys, which cease to be man-shaped; and
indeed the Gibbons and Siamangs, although man-shaped (Anthropomorpha),
occupy neutral ground between the Orangs and the Cynomorpha.
Formerly, in those ages when the Orang lived on the continent of India,
the Gibbons roamed far over the vast land surfaces of the period, and
lived in Southern France. Portions of the skeleton of an Ape as large
as a man, but which resembled the Hylobates, were found there, and
named _Dryopithecus_, in strata of Mid-Tertiary age.
In concluding this part of the subject, which relates especially to
the man-shaped Apes, some very obvious reflections occur. There is
something very interesting as well as instructive and suggestive in
the study of the proportions of the limbs to each other and to the
body in the larger Apes, of which the Gorilla is the highest in the
scale, and in man. The fingers in man hang down to below the middle of
the thigh; in the Gorilla they attain the knee; in the Chimpanzee they
reach below the knee; in the Orang they touch the ankle; in the Siamang
they reach the sole; and in some Gibbons the whole palm may be applied
to the ground without the trunk being bent forward beyond its natural
position on the legs. It is also found that in man the arm-bone exceeds
in length each of the bones of the fore-arm in a marked manner, and in
the Gorilla and Chimpanzee it does so but slightly; the bones are equal
in the Orangs, and very unequal in the Gibbons, those of the fore-arm
being the longest. When the length of the arms down to the wrist
is compared with that of the body, omitting the legs, there is not
much difference between man and the Gorilla, but it increases in the
Chimpanzee, Orang, and in the Siamang. The lower limbs are short in the
Gorilla, and this is characteristic--they offer but a poor support to
the huge body--and the resemblance to the symmetrical proportion of the
legs to the body in man is scanty indeed. This disproportion is greater
in the Chimpanzee and Orangs, in which the lower limbs are pigmies.
[Illustration: JAW OF THE GIBBON.]
Consider the hand in the same manner. Man’s perfect hand, writes Owen,
is one of his peculiar physical characters, and that perfection is
mainly due to the differences of the first and the other four fingers,
and the ability of this first to be opposed to them, as a perfect
thumb. A partially opposable thumb, that is to say, one which can be
brought over the palm, more or less, is present in the hand of the
great Apes. It is large in the Gorilla, so far as Apes are concerned,
and it reaches, when it and the fingers are stretched out, to just
a little beyond the first joint of the first finger, or rather of
its first movable part. But in the Chimpanzee and Orang it does not
reach to the joint, and it is longest and strongest in proportion in
the Gibbons (_Hylobates_). In the Gorilla and the Chimpanzee, the
wrist-bones are eight in number, but there are nine in the Orangs and
Gibbons.
[Illustration: BACK OF JAW OF THE AGILE GIBBON.]
The toe-thumb is about five-twelfths of the length of the whole foot in
the Gorilla, and it is slightly longer in the Chimpanzee and Hylobates,
but it is not more than a fourth of the length of the foot in Orangs.
The nails of all the fingers and toes of the great Apes are flattened,
except in the Hylobates, whose thumb and toe-thumb nails only are so;
the rest are more claw-like.
Finally, as regards the brain and nervous system. In the man-shaped
Apes the brain is smaller as compared with the nerves which proceed
from it than in man; and the brain proper is smaller relatively to the
cerebellum than in man. The convolutions, the fissures, and eminences
of the brain are generally less complex, and those of the two sides
or hemispheres of the brain are more symmetrical than in man. The
sides of the brain or the hemispheres are rounder and deeper in man,
and the proportions of their lobes to one another are different. Some
convolutions and fissures present in man are less perfectly formed, but
still exist in the Apes, and the cerebellum is not covered entirely in
the Hylobates, but it is in the other Anthropomorpha.