body, now we must consider that of the human mind. In seeking through
the animal kingdom for the probable ancestor of man in his bodily
aspect, we were drawn irresistibly to the ape tribe, as the only one
that made any near approach to him in structure. In considering the case
from the point of view of mental development we find a similar
irresistible drawing toward the apes, as the most spontaneously
intelligent of the mammalia. While many of the lower animals are capable
of being taught, the ape stands nearly alone in the power of thinking
for itself, the characteristic of self-education.
Innumerable testimonials could be quoted from observers in evidence of
the superior mental powers of the apes. Hartmann says of them that
"their intelligence sets them high above other mammals," and Romanes
that they "certainly surpass all other animals in the scope of their
rational faculty." It is scarcely necessary here to give extended
examples of ape intelligence. Hundreds of instances are on record, many
of them showing remarkable powers of reasoning for one of the lower
animals. The ape, it is true, is not alone in its teachableness. Nearly
all the domestic animals can be taught, the dog and the elephant to a
considerable degree. And evidences of reasoning out some subject for
themselves now and then appear in the domesticated species; but these
are rare instances, not frequent acts as in the case of the apes.
The apes, indeed, rarely need teaching. They observe and imitate to an
extent far beyond that displayed by any others of the lower animals, and
the more remarkable from the fact that in nearly every instance the
animals concerned began life in the wild state, and had none of the
advantages of hereditary influence possessed by the domesticated dog and
horse. Among the most interesting examples of spontaneous acts of
intelligence of the ape tribe are those related by Romanes, in his
"Animal Intelligence," of the doings of a cebus monkey, which he kept
for several months under close observation in his own house. Instead of
selecting general examples of ape actions, we may cite some of the
doings of this intelligent creature.
The cebus did not wait to be shown how to do things, but was an adept in
devising ways to do them himself. He had the monkey love of mischief
well developed, and not much that was breakable came whole from his
hands. When he could not break an egg cup by dashing it to the ground,
he hammered it on the post of a brass bedstead until it was in
fragments. In breaking a stick, he would pass it down between a heavy
object and the wall, and break it by hanging on its end. In destroying
an article of dress, he would begin by carefully pulling out the
threads, and afterward tear it to pieces with his teeth. His nuts he
broke with a hammer precisely as a man would have done and without being
shown its use. Ridicule was not pleasant to him; he strongly resented
being laughed at, and would throw anything within reach at his tormentor
and with a skill and force not usual with monkeys. Taking the missile in
both hands and standing erect, he would extend his long arms behind his
back and hurl the article by bringing them forcibly forward.
If any object he wanted was too far away to reach, he would draw it
toward him with a stick. Failing in this, he was observed to throw a
shawl back over his head, and then fling it forward with all his
strength, holding it by two corners. When it fell over the object, he
brought this within reach by drawing in the shawl. In his gyrations,
the chain by which he was fastened often became twisted around some
object. He would now examine it intently, pulling it in opposite ways
with his fingers until he had discovered how the turns ran. This done,
he would carefully reverse his motions until the chain was quite
disentangled.
The most striking act of intelligence told of this creature was his
dealings with a hearth-brush which fell into his hands, and of which the
handle screwed into the brush. It took him no long time to find out how
to unscrew the handle. When this was achieved, he at once began to try
and screw it in again. In doing so he showed great ingenuity. At first
he put the wrong end of the handle into the hole, and turned it round
and round in the right direction for screwing. Finding this would not
work, he took it out and tried the other end, always turning in the
right direction. It was a difficult feat to perform, as he had to turn
the screw with both hands, while the flexible bristles of the brush
prevented it from remaining steady. To aid his operations he now held
the brush with one foot, while turning with both hands. It was still
difficult to make the first turn of the screw, but he worked on with
untiring perseverance until he got the thread to catch, and then screwed
it in to the end. The remarkable thing was that he never tried to turn
the handle in the wrong direction, but always screwed it from left to
right, as if he knew that he must reverse the original motion. The feat
accomplished, he repeated it, and continued to do so until he could
perform it easily. Then he threw the brush aside, apparently taking no
more interest in that over which he had worked so persistently. No man
could have devoted himself more earnestly to learn some new art, and
become more indifferent to it when once learned. These are a few only of
the many acts of intelligence observed by Mr. Romanes in the doings of
this animal. They will suffice as examples of what we mean by
spontaneous intelligence. The cebus did not need to be shown how to do
things; it worked them out for itself much as a man would have done,
performing acts of an intricacy far beyond any ever observed in other
classes of animals in captivity. It may be said further that the
displays of spontaneous intelligence shown by dogs, cats, and similar
animals have usually been intended in some way for the advantage of the
animal; few or none are on record which indicate a mere desire to know
without ulterior advantage; no persevering effort, like that with the
brush, which is purely an instance of self-instruction.
Examples of intelligence of this advanced character could be cited from
observation of monkeys of various species. The anthropoid apes have not
been brought to any large extent under observation, but are notable for
their intelligence in captivity. It is not easy to observe them in a
state of nature, and nearly all we know is that the orang makes itself
a nightly bed of branches broken off and carefully laid together, and is
said to cover itself in bed with large leaves, if the weather is wet.
The chimpanzee has a similar habit, and the gorilla is said to build
itself a nest in which the female and the young sleep, the old male
resting at the foot of the tree, on guard against their dangerous foe,
the leopard.
It is the young animals of these species which are the most social and
docile and most approach man in appearance. As they grow older, their
specific characters become more marked. Fierce and sullen as is the old
gorilla, the young of this species is playful and affectionate in
captivity and is given to mischievous tricks. The one that was kept for
a time in Berlin showed much good-nature, playfulness, and intelligence,
and some degree of monkey mischievousness. It was very cunning in
carrying out its plans, particularly in stealing sugar, of which it was
very fond.
The chief examples of anthropoid intelligence are told of the
chimpanzee, which has been most frequently kept in captivity. It is
usually lively and good-tempered and is very teachable. Some of the
stories of its intelligence may be apocryphal, as those told by Captain
Grandpre of a chimpanzee which performed all the duties of a sailor on
board ship, and of one that would heat the oven for a baker and inform
him when it was of the right temperature. But there are authenticated
stories of chimpanzee intelligence which give it a high standing in
this respect among the lower animals.
The emotional nature of the ape is also highly developed. It displays an
affection equal to that of the dog, and a sympathy surpassing that of
any other animal below man. The feeling displayed by monkeys for others
of their kind in pain is of the most affecting nature, and Brehm relates
that in the monkeys of certain species kept under confinement by him in
Africa, the grief of the females for the loss of their young was so
intense as to cause their death. More than once an ardent hunter has
seen such examples of tender solicitude among monkeys for the wounded
and of grief for the dead as to resolve never to fire at one of the race
again.
James Forbes, in his "Oriental Memoirs," relates a striking instance of
this kind. One of a shooting party had killed a female monkey in a
banian tree, and carried it to his tent. Forty or fifty of the tribe
soon gathered around the tent, chattering furiously and threatening an
attack, from which they were only diverted by the display of the
fowling-piece, whose effects they seemed perfectly to understand. But
while the others retreated, the leader of the troop stood his ground,
continuing his threatening chatter. Finding this of no avail, he came to
the door of the tent, moaning sadly, and by his gestures seeming to beg
for the dead body. When it was given, he took it sorrowfully up in his
arms and carried it away to the waiting troop. That hunter never shot a
monkey again.
This deep feeling for the dead is probably not common among monkeys. The
gibbon, for instance, is said to take no notice of the dead. It is,
however, highly sympathetic to injured and sick companions, and this
feeling seems common to all the apes. No human being could show more
tender care of wounded or helpless companions than has often been seen
in members of this affectionate tribe of animals.
Without giving further examples of the intelligence and sympathy of the
apes, we may say that they possess in a marked degree the mental powers
to which man owes so much, viz. observation and imitation. The ape is
the most curious of the lower animals--that is, it possesses the faculty
of observation in an unusual degree. What we call curiosity in the ape
is the basic form of the characteristic which we call attention or
observation in man. Its seeming great activity in the ape is what might
naturally be expected in an observant animal when removed from its
natural habitat to a location where all around it is new and strange.
Man under like circumstances is as curious as the ape, while the latter
in its native trees probably finds little to excite its special
attention. In both man and the ape it needs novelty to excite curiosity.
Again, the ape is imitative in a high degree. This faculty also it does
not share with the lower animals, but does with man, imitation being
one of the methods by which he has attained his supremacy. Observation,
imitation, education, are the three levers in the development of the
human intellect. The first two of these the ape possesses in a marked
degree. It is susceptible also to the last, being very teachable.
Education certainly exists to some extent among the apes in their
natural habitat, perhaps to as great an extent as it did in primitive
man. In the latter case it is doubtful if there was much that could be
called designed education, the young gaining their degree of knowledge by
observing and imitating their elders. The same is certainly the case
among the apes.
We may reasonably ask what there is in the life and character of the
apes to give them this mental superiority over the remaining lower
animals. It is certainly not due to the arboreal life and powers of
grasp of these animals, for in those respects they resemble the lemurs,
which are greatly lacking in intelligence. Whether the monkeys emerged
from the lemurs or the two groups developed side by side is a question
as yet unsettled; at all events they are closely similar in conditions
of existence. Yet while the monkeys are the most intelligent and
teachable of animals, the lemurs are among the least intelligent of the
mammalia. There is here a marked distinction which is evidently not due
to difference of structure or habitat, and must have its origin in some
other characteristic, such as difference in life habits.
There is certainly nothing in the diet of the ape to develop
intelligence. The frugivorous and herbivorous animals do not need
cunning and shrewdness to anything like the extent necessary in
carnivorous animals. They do not need to pursue or lie in wait for prey;
and they escape from their enemies mainly through strength, speed,
concealment, or other physical powers or methods. Escape may
occasionally develop mental alertness, but does not usually do so.
Certainly if the alert, watchful, suspicious habits of the apes are due
to the requisite of avoiding dangerous enemies, we might naturally look
for similar habits in the lemurs, which are similarly situated. And if
we consider the wide distribution of the apes throughout the tropics of
both hemispheres, and their great diversity in species and condition, it
seems very unlikely that in all these localities their relations with
other animals would be such as to develop the mental alertness which
they so generally display. The fact appears to be that, while this may
be a cause, it is not a leading cause, of mental development in animals,
and that we must seek elsewhere for the origin of animal intelligence.
Research, indeed, leads us to examples of intelligence where we should
least expect to find it. Among the mammalia we perceive one marked
example in the beavers, the only one in the great class of the rodents,
with their nine hundred or more of species. But we must go still lower,
to the insects, for the most striking examples, finding them alone in
the ants, the bees, and the termites, among the vast multitude of insect
forms. Less marked instances appear in the elephants, in some of the
birds, and in certain other gregarious animals.
From these examples, and what is elsewhere known of animal intelligence,
one broad conclusion may be drawn, that all the strikingly intelligent
animals are strongly social in their habits, and that no decided display
of intelligence is to be found among solitary species. This conclusion
becomes almost a demonstration in the case of the ants and bees. The
ants, for instance, comprise hundreds of species, spread over most of
the world, mainly social, but occasionally solitary. The social species,
while varying greatly in habit, all display powers of intelligence, and
these so diversified as to indicate many separate lines of evolution.
The solitary ants, on the contrary, manifest no special intelligence,
and do not rise above the general insect level. The same may be said of
the bees. The hive bee, the most communal in habit, shows the highest
traits of intelligent activity. The bees which form smaller groups and
the social wasps stand at a lower level, and the solitary bees and wasps
sink to the ordinary insect plane. We arrive at like conclusions from
observation of the social termites, or white ants, some species of
which are remarkable for their intelligent cooeperation and division of
duties.
Examples similar in kind may be drawn from the vertebrates. Among the
birds there are none more quick-witted than the social crows, none with
less display of intelligence than the solitary carnivorous species.
Birds are rather gregarious than social. There are few species whose
association is above that of mere aggregation in flight. Those more
distinctively social usually have special habits which indicate
intelligence--as in the often cited instances of their seemingly trying
and executing delinquents. Among the carnivorous mammals the social dog
or wolf tribe displays the intelligent habit of mutual aid. The horses,
oxen, deer, and other gregarious hoofed animals have a degree of
division of duties, but their intelligence is of a lower grade than that
of the dogs and the elephants. On the whole, it may be affirmed that the
social habit is frequently accompanied by instances of special
intelligence to which we find no counterpart among the solitary forms,
and that the highest manifestations of intelligence in the lower animals
are found in those forms which possess communal habits, as the ants,
bees, termites, and beavers.
One important characteristic of the communal animals is that they become
mentally specialized. They round up their powers, build barriers of
habit over which they cannot pass, perform the same acts with such
interminable iteration that what began as intellect sinks back into
instinct. Each individual has fixed duties and is confined within a
limited circle of acts, whose scope it cannot pass, or only to the
minutest extent.
The non-communal social animals, on the contrary, are not thus
restricted. Their intelligence is of a generalized character, and is
capable of developing in new channels. None are tied down to special
duties, each possesses the full powers of all, and they are thus more
open to a continued growth of the intellect than the communal forms. To
this class belongs the ape. Its intelligence is general, not special;
broadly capable of development, not narrowed and bound in by the
limitation of certain fixed and special duties.
The suggestions above offered point to three grades of community among
animals, which may be designated the communal, the social, and the
solitary. Among these there are, of course, many stages of transition
from one to the other. The specially communal, including the ants, bees,
termites, and beavers, are those in which there is almost a total loss
of individuality, each member working for the good of the community as a
unit, not for its personal advantage. The result consists in organized
industries, division and specialization of duties, a common home, food
stock, etc. At a lower level in animal life, that of the hydroid polyps,
communism has become so complete that the community has grown into an
actual individual, the members not being free, but acting as organs of
an aggregate mass, in which each performs some special duty for the good
of the community.
The social animals differ from the communal in that the individuality of
the members is fully preserved. There is some measure of work for the
group, some degree of mutual aid, some evidence of leadership and
subordination, but these are confined to a few exigencies of life, while
in most of the details of existence each member of the group acts for
itself. The solitary animals are those which do not form groups larger
than that of the family, and into whose life the principle of mutual
aid, outside the immediate family relations, does not enter. Each acts
for itself alone, and intercourse between the individuals of the species
is greatly restricted.
The advantages of social habits among animals are evident. There is
excellent reason to believe that all animals, and especially such
advanced forms as the vertebrates and the higher arthropods, have some
power of mental development, some facility in devising new methods of
action to meet new situations. Though their reasoning power may be
small, it is not quite lacking, and many examples of the exercise of the
faculty of thought could be cited if necessary.
What we are here concerned with, is the final result of such exercises
of individual thought powers. In the case of the solitary forms, such
new conceptions die with the individual. Though they may exert an
influence on the development of the nervous system, and aid in the
hereditary transmission of more active brain powers, they are lost as
special ideas, fail to be taken up and repeated by other members of the
species. This is not the case with the social animals. Each of these has
some faculty of observation and some tendency to imitation, and useful
steps of advance made by individuals are likely to be observed and
retained as general habits of the community. Anything of importance that
is gained may be preserved by educative influences. The facility of
mental communication between these creatures is perhaps much greater
than is generally supposed, and acts of importance which are not
directly observed might in many cases be transmitted through repetition
for the benefit of the group. We know this to be the main agency in
human progress. New ideas are of rare occurrence with man. Ideas of
permanent value do not occur to one per cent., perhaps not to one
hundredth of one per cent., of civilized mankind, yet few of such ideas
are lost, and that which has proved of advantage to an individual soon
becomes the common possession of a community.
Among the lower animals new and advantageous ideas are probably of
exceedingly rare occurrence. When they do occur, their advantage to
solitary forms is very slight, being that of minute steps of brain
development and hereditary transmission of the same. To social forms
they are doubly advantageous, since, while they tend to brain
development, they may also be preserved in their original form, and
transmitted directly to members of the group. They are still more
advantageous to the communal animals, from the closer intercourse of
these, and their constant association in acts of mutual aid. But in the
latter instance their influence is usually exerted for the benefit of
the community as a unit, while in the case of social animals it is of
advantage to the individual.
The result of such a process of evolution in the case of the communal
animals is a strict specialism. A series of acts of advantage to the
community are slowly developed, and are repeated so frequently that they
become instinctive, while a fixed circle of duties arises, through whose
links it is almost impossible to break. There is no reason to believe
that the individual initiative is wanting. The varied round of duties of
a community of ants, for instance, could only have arisen through step
after step of progress from the condition of the solitary ants. If such
steps have been made, others may be made, and are likely to be preserved
if found advantageous. The ant individual preserves its powers of
observation and thought and may initiate new processes. But most of the
ant communities are already so excellently adapted to the conditions of
their life as to leave little opportunity for improvement, so that the
adoption of new and advantageous habits are certain to be exceedingly
rare.
It is an interesting fact that communalism has been confined to animals
of comparatively low organization. The most complete examples of it
exist in the polyps and some other low forms, in which each community
has become a compound individual, the members remaining attached to the
parent stock. The next higher examples to be met are the frequently
cited ants and bees, belonging to the lowly organized class of
arthropoda, yet, through the advantage of association and mutual aid,
developing actions and habits only found elsewhere in the human race.
The only example among vertebrates is that of the beavers, members of
the low order of rodents. With these the results are less varied and
intricate than with the ants, in accordance with the much smaller size
of the community. All the higher vertebrates are either social or
solitary in habit, and among them the narrow specialism of the communal
forms does not exist. Each individual works in large measure for itself,
its mental powers remain generalized, and it is not tied down to the
performance of a series of fixed hereditary acts from which escape is
well-nigh impossible.