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IX DO ANIMALS THINK
AND REFLECT? “‘WHEN we see the animals going about, living their lives in many ways as we live ours, seeking their food, avoiding their enemies, building their nests, digging their holes, laying up stores, migrating, courting, playing, fighting, showing cunning, courage, fear, joy, anger, rivalry, grief, profiting by experience, following their leaders, — when we see all this, I say, what more natural than that we should ascribe to them powers akin to our own, and look upon them as thinking, reasoning, and reflecting. A hasty survey of animal life is sure to lead to this conclusion. An animal is not a clod, nor a block, nor a machine. It is alive and self-directing, it has some sort of psychic life, yet the more I study the subject, the more I am persuaded that with the probable exception of the dog on occasions, and of the apes, animals do not think or reflect in any proper sense of those words. As I have before said, animal life shows in an active and free state that kind of intelligence that pervades and governs the whole organic world, — intelligence that takes no thought of itself. Here, in front of my window, is a black raspberry bush. A few weeks ago its branches curved upward, with their ends swinging fully two feet above the ground; now those ends are thrust down through the weeds and are fast rooted to the soil. Did the raspberry bush think, or choose what it should do? Did it reflect and say, Now is the time for me to bend down and thrust my tip into the ground? To all intents and purposes yes, yet there was no voluntary mental process, as in similar acts of our own. We say its nature prompts it to act thus and thus, and that is all the explanation we can give. Or take the case of the pine or the spruce tree that loses its central and leading shoot. When this happens, does the tree start a new bud and then develop a new shoot to take the place of the lost leader? No, a branch from the first ring of branches below, probably the most vigorous of the whorl, is promoted to the leadership. Slowly it rises up, and in two or three years it reaches the upright position and is leading the tree upward. This, I suspect, is just as much an act of conscious intelligence and of reason as is .much to which we are so inclined to apply those words in animal life. I suppose it is all foreordained in the economy of the tree, if we could penetrate that economy. It is in this sense that Nature thinks in the animal, and the vegetable, and the mineral worlds. Her thinking is more flexible and adaptive in the vegetable than in the mineral, and more so in the animal than in the vegetable, and the most so of all in the mind of man. The way the wild
apple trees and the red thorn trees in the pasture, as described by Thoreau,
triumph over the cattle that year after year browse them down, suggests
something almost like human tactics. The cropped and bruised tree, not being
allowed to shoot upward, spreads more and more laterally, thus pushing its
enemies farther and farther away, till, after many years, a shoot starts up
from the top of the thorny, knotted cone, and in one season, protected by this cheval-de-frise, rise, attains a height
beyond the reach of the cattle, and the victory is won. Now the whole push of
the large root system goes into the central shoot and the tree is rapidly
developed. This almost looks
like a well-laid scheme on the part of the tree to defeat its enemies. But see
how inevitable the whole process is. Check the direct flow of a current and it
will flow out at the sides; check the side issues and they will push out on
their sides, and so on. So it is with the tree or seedling. The more it is
cropped, the more it branches and rebranches, pushing out laterally as its
vertical growth is checked, till it has surrounded the central stalk on all
sides with a dense, thorny hedge. Then as this stalk is no longer cropped, it
leads the tree upward. The lateral branches are starved, and in a few years the
tree stands with little or no evidence of the ordeal it has passed through. In
like manner the nature of the animals prompts them to the deeds they do, and we
think of them as the result of a mental process, because similar acts in
ourselves are the result of such a process. See how the mice
begin to press into our buildings as the fall comes on. Do they know winter is
coming? In the same way the vegetable world knows it is coming when it
prepares for winter, or the insect world when it makes ready, but not as you
and I know it. The woodchuck “holes up” in late September; the crows flock and
select their rookery about the same time, and the small wood newts or
salamanders soon begin to migrate to the marshes. They all know winter is coming, just as much as the tree knows, when
in August it forms its new buds for the next year, or as the flower knows that
its color and perfume will attract the insects, and no more. The general
intelligence of nature settles all these and similar things. When a bird selects
a site for its nest, it seems, on first view, as if it must actually think,
reflect, compare, as you and I do when we decide where to place our house. I
saw a little chipping sparrow trying to decide between two raspberry bushes.
She kept going from one to the other, peering, inspecting, and apparently
weighing the advantages of each. I saw a robin in the woodbine on the side of
the house trying to decide which particular place was the best site for her
nest. She hopped to this tangle of shoots and sat down, then to that, she
turned around, she readjusted herself, she looked about, she worked her feet
beneath her, she was slow in making up her mind. Did she make up her mind? Did
she think, compare, weigh? I do not believe it. When she found the right
conditions, she no doubt felt pleasure and satisfaction, and that settled the
question. An inward, instinctive want was met and satisfied by an outward
material condition. In the same way the hermit crab goes from shell to shell
upon the beach, seeking one to its liking. Sometimes two crabs fall to fighting
over a shell that each wants. Can we believe that the hermit crab thinks and
reasons? It selects the suitable shell instinctively, and not by an individual
act of judgment. Instinct is not always inerrant, though it makes fewer
mistakes than reason does. The red squirrel usually knows how to come at the
meat in the butternut with the least gnawing, but now and then he makes a
mistake and strikes the edge of the kernel, instead of the flat side. The cliff
swallow will stick her mud nest under the eaves of a barn where the boards are
planed so smooth that the nest sooner or later is bound to fall. She seems to
have no judgment in the matter. Her ancestors built upon the face of high
cliffs, where the mud adhered more firmly. A wood thrush began
a nest in one of my maples, as usual making the foundation of dry leaves, bits
of paper, and dry grass. After the third day the site on the branch was bare,
the wind having swept away every vestige of the nest. As I passed beneath the
tree I saw the thrush standing where the nest had been, apparently in deep
thought. A few days afterward I looked again, and the nest was completed. The
bird had got ahead of the wind at last. The nesting-instinct had triumphed over
the weather. Take the case of
the little yellow warbler when the cowbird drops her egg into its nest — does
anything like a process of thought or reflection pass in the bird’s mind then?
The warbler is much disturbed when she discovers the strange egg, and her mate
appears to share her agitation. Then after a time, and after the two have
apparently considered the matter together, the mother bird proceeds to bury the
egg by building another nest on top of the old one. If another cowbird’s egg is
dropped in this one, she will proceed to get rid of this in the same way. This all
looks very like reflection. But let us consider the matter a moment. This thing
between the cowbird and the warbler has been going on for innumerable
generations. The yellow warbler seems to be the favorite host of this parasite,
and something like a special instinct may have grown up in the warbler with
reference to this strange egg. The bird reacts, as the psychologists say, at
sight of it, then she proceeds to dispose of it in the way above described. All yellow warblers act in the same manner,
which is the way of instinct. Now if this procedure was the result of an
individual thought or calculation on the part of the birds, they would not all
do the same thing; different lines of conduct would be hit upon. How much
simpler and easier it would be to throw the egg out — how much more like an act
of rational intelligence. So far as I know, no bird does eject this parasitical
egg, and no other bird besides the yellow warbler gets rid of it in the way I
have described. I have found a deserted phoebe’s nest with one egg of the
phoebe and one of the cowbird in it. Some of our wild
birds have changed their habits of nesting, coming from the woods and the rocks
to the protection of our buildings. The phoebe-bird and the cliff swallow are
marked examples. We ascribe the change to the birds’ intelligence, but to my
mind it shows only their natural adaptiveness. Take the cliff swallow, for
instance; it has largely left the cliffs for the eaves of our buildings. How
naturally and instinctively this change has come about! In an open farming
country insect life is much more varied and abundant than in a wild, unsettled
country. This greater food supply naturally attracts the swallows. Then the
protecting eaves of the buildings would stimulate their nesting-instincts. The
abundance of mud along the highways and about the farm would also no doubt
have its effect, and the birds would adopt the new sites as a matter of course.
Or take the phoebe, which originally built its nest under ledges, and does so
still to some extent. It, too, would find a more abundant food supply in the
vicinity of farm-buildings and bridges. The protected nesting-sites afforded
by sheds and porches would likewise stimulate its nesting-instincts, and
attract the bird as we see it attracted each spring. Nearly everything
an animal does is the result of an inborn instinct acted upon by an outward
stimulus. The margin wherein intelligent choice plays a part is very small.
But it does at times play a part — perceptive intelligence, but not rational
intelligence. The insects do many things that look like intelligence, yet how
these things differ from human intelligence may be seen in the case of one of
our solitary wasps, — the mud-dauber, — which sometimes builds its cell with
great labor, then seals it up without laying its egg and storing it with the
accustomed spiders. Intelligence never makes that kind of a mistake, but
instinct does. Instinct acts more in the invariable way of a machine. Certain
of the solitary wasps bring their game — spider, or bug, or grasshopper — and
place it just at the entrance of their hole, and then go into their den
apparently to see that all is right before they carry it in. Fabre, the French
naturalist, experimented with one of these wasps, as follows: While the wasp
was in its den he moved its grasshopper a few inches away. The wasp came out,
brought it to the opening as before, and went within a second time; again the
game was removed, again the wasp came out and brought it back and entered her
nest as before. This little comedy was repeated over and over; each time the
wasp felt compelled to enter her hole before dragging in the grasshopper. She
was like a machine that would work that way and no other. Step must follow step
in just such order. Any interruption of the regular method and she must begin
over again. This is instinct, and the incident shows how widely it differs from
conscious intelligence. If you have a tame
chipmunk, turn him loose in an empty room and give him some nuts. Finding no
place to hide them, he will doubtless carry them into a corner and pretend to
cover them up. You will see his paws move quickly about them for an instant as
if in the act of pulling leaves or mould over them. His machine, too, must work
in that way. After the nuts have been laid down, the next thing in order is to
cover them, and he makes the motions all in due form. Intelligence would have
omitted this useless act. A canary-bird in
its cage will go through all the motions of taking a bath in front of the cup
that holds its drinking-water when it can only dip its bill into the liquid.
The sight or touch of the water excites it and sets it going, and with now and
then a drop thrown from its beak it will keep up the flirting and fluttering
motion of its tail and wings precisely as if taking a real instead of an
imaginary bath. Attempt to thwart
the nesting-instinct in a bird and see how persistent it is, and how blind! One
spring a pair of English sparrows tried to build a nest on the plate that
upholds the roof of my porch. They were apparently attracted by an opening
about an inch wide in the top of the plate, that ran the whole length of it.
The pair were busy nearly the whole month of April in carrying nesting-material
to various points on that plate. That big crack or opening which was not large
enough to admit their bodies seemed to have a powerful fascination for them.
They carried straws and weed stalks and filled up one portion of it, and then
another and another, till the crack was packed with rubbish from one end of the
porch to the other, and the indignant broom of the housekeeper grew tired of
sweeping up the litter. The birds could not effect an entrance into the
interior of the plate, but they could thrust in their nesting-material, and so
they persisted week after week, stimulated by the presence of a cavity beyond
their reach. The case is a good illustration of the blind working of instinct. Animals have keen
perceptions, — keener in many respects than our own, — but they form no conceptions,
have no powers of comparing one thing with another. They live entirely in and
through their senses. It is as if the
psychic world were divided into two planes, one above the other, — the plane of
sense and the plane of spirit. In the plane of sense live the lower animals,
only now and then just breaking for a moment into the higher plane. In the
world of sense man is immersed also — this is his start and foundation; but he
rises into the plane of spirit, and here lives his proper life. He is
emancipated from sense in a way that beasts are not. Thus, I think, the
line between animal and human psychology may be pretty clearly drawn. It is not
a dead-level line. Instinct is undoubtedly often modified by intelligence, and
intelligence is as often guided or prompted by instinct, but one need not
hesitate long as to which side of the line any given act of man or beast
belongs. When the fox resorts to various tricks to outwit and delay the hound
(if he ever consciously does so), he exercises a kind of intelligence, — the lower
form which we call cunning, — and he is prompted to this by an instinct of
self-preservation. When the birds set up a hue and cry about a hawk or an owl,
or boldly attack him, they show intelligence in its simpler form, the intelligence
that recognizes its enemies, prompted again by the instinct of
self-preservation. When a hawk does not know a man on horseback from a horse,
it shows a want of intelligence. When a crow is kept away from a corn-field by
a string stretched around it, the fact shows how masterful is its fear and how
shallow its wit. When a cat or a dog, or a horse or a cow, learns to open a
gate or a door, it shows a degree of intelligence — power to imitate, to profit
by experience. A machine could not learn to do this. If the animal were to
close the door or gate behind it, that would be another step in intelligence.
But its direct wants have no relation to the closing of the door, only to the
opening of it. To close the door involves an after-thought that an animal is
not capable of. A horse will hesitate to go upon thin ice or upon a frail
bridge, even though it has never had any experience with thin ice or frail
bridges. This, no doubt, is an inherited instinct, which has arisen in its
ancestors from their fund of general experience with the world. How much with
them has depended upon a secure footing! A pair of house wrens had a nest in my
well-curb; when the young were partly grown and heard any one come to the curb,
they would set up a clamorous calling for food. When I scratched against the
sides of the curb beneath them like some animal trying to climb up, their
voices instantly hushed; the instinct of fear promptly overcame the instinct of
hunger. Instinct is intelligent, but it is not the same as acquired individual
intelligence; it is untaught. When the nuthatch
carries a fragment of a hickory-nut to a tree and wedges it into a crevice in
the bark, the bird is not showing an individual act of intelligence: all
nuthatches do this; it is a race instinct. The act shows intelligence, — that
is, it adapts means to an end, — but it is not like human or individual
intelligence, which adapts new means to old ends, or old means to new ends, and
which springs up on the occasion. Jays and chickadees hold the nut or seed they
would peek under the foot, but the nuthatch makes a vise to hold it of the bark
of the tree, and one act is just as intelligent as the other; both are the
promptings of instinct. But when man makes a vise, or a wedge, or a bootjack,
he uses his individual intelligence. When the jay carries away the corn you put
out in winter and hides it in old worms’ nests and knot-holes and crevices in
trees, he is obeying the instinct of all his tribe to pilfer and hide things, —
an instinct that plays its part in the economy of nature, as by its means many
acorns and chestnuts get planted and large seeds widely disseminated. By this
greed of the jay the wingless nuts take flight, oaks are planted amid the
pines, and chestnuts amid the hemlocks. Speaking of nuts
reminds me of an incident I read of the deer or white-footed mouse — an incident
that throws light on the limitation of animal intelligence. The writer gave the
mouse hickory-nuts, which it attempted to carry through a crack between the
laths in the kitchen wall. The nuts were too large to go through the crack. The
mouse would try to push them through; failing in that, he would go through and
then try to pull them after him. All night he or his companion seems to have
kept up this futile attempt, fumbling and dropping the nut every few minutes.
It never occurred to the mouse to gnaw the hole larger, as it would instantly
have done had the hole been too small to admit its own body. It could not
project its mind thus far; it could not get out of itself sufficiently to
regard the nut in its relation to the hole, and it is doubtful if any
four-footed animal is capable of that degree of reflection and comparison.
Nothing in its own life or in the life of its ancestors had prepared it to meet
that kind of a difficulty with nuts. And yet the writer who made the above
observation says that when confined in a box, the sides of which are of unequal
thickness, the deer mouse, on attempting to gnaw out, almost invariably
attacks the thinnest side. How does he know which is the thinnest side?
Probably by a delicate and trained sense of feeling or hearing. In gnawing
through obstructions from within, or from without, he and his kind have had
ample experience. Now when we come to
insects, we find that the, above inferences do not hold. It has been observed
that when a solitary wasp finds its hole in the ground too small to admit the
spider or other insect which it has brought, it falls to and enlarges it. In
this and in other respects certain insects seem to take the step of reason that
quadrupeds are incapable of. Lloyd Morgan
relates at some length the experiments he tried with his fox terrier, Tony,
seeking to teach him how to bring a stick through a fence with vertical
palings. The spaces would allow the dog to pass through, but the palings caught
the ends of the stick which the dog carried in his mouth. when his master
encouraged him, he pushed and struggled vigorously. Not succeeding, he went
back, lay down, and began gnawing the stick. Then he tried again, and stuck as
before, but by a chance movement of his head to one side finally got the stick
through. His master patted him approvingly and sent him for the stick again.
Again he seized it by the middle, and of course brought up against the palings.
After some struggles he dropped it and came through without it. Then,
encouraged by his master, he put his head through, seized the stick, and tried
to pull it through, dancing up and down in his endeavors. Time after time and
day after day the experiment was repeated with practically the same results.
The dog never mastered the problem. He could not see the relation of that stick
to the opening in the fence. At one time he worked and tugged three minutes
trying to pull the stick through. Of course, if he had had any mental
conception of the problem or had thought about it at all, a single trial would
have convinced him as well as would a dozen trials. Mr. Morgan tried the
experiment with other dogs with like result. When they did get the stick
through, it was always by chance. It has never been
necessary that the dog or his ancestors should know how to fetch long sticks
through a narrow opening in a fence. Hence he does not know the trick of it.
But we have a little bird that knows the trick. The house wren will carry a
twig three inches long through a hole of half that diameter. She knows how to
manage it because the wren tribe have handled twigs so long in building their
nests that this knowledge has become a family instinct. What we call the
intelligence of animals is limited for the most part to sense perception and
sense memory. We teach them certain things, train them to do tricks quite
beyond the range of their natural intelligence, not because we enlighten their
minds or develop their reason, but mainly by the force of habit. Through repetition
the act becomes automatic. Who ever saw a trained animal, unless it be the
elephant, do anything that betrayed the least spark of conscious intelligence?
The trained pig, or the trained dog, or the trained lion does its “stunt”
precisely as a machine would do it — without any more appreciation of what it
is doing. The trainer and public performer find that things must always be done
in the same fixed order; any change, anything unusual, any strange sound,
light, color, or movement, and trouble at once ensues. I read of a beaver
that cut down a tree which was held in such a way that it did not fall, but simply
dropped down the height of the stump. The beaver cut it off again; again it
dropped and refused to fall; he cut it off a third and a fourth time: still
the tree stood. Then he gave it up. Now, so far as I can see, the only
independent intelligence the animal showed was when it ceased to cut off the
tree. Had it been a complete automaton, it would have gone on cutting — would
it not? — till it made stove-wood of the whole tree. It was confronted by a new
problem, and after a while it took the hint. Of course it did not understand
what was the matter, as you and I would have, but it evidently concluded that
something was wrong. Was this of itself an act of intelligence? Though it may
be that its ceasing to cut off the tree was simply the result of
discouragement, and involved no mental conclusion at all. It is a new problem,
a new condition, that tests an animal’s intelligence. How long it takes a caged
bird or beast to learn that it cannot escape! What a man would see at a glance
it takes weeks or months to pound into the captive bird, or squirrel, or coon.
When the prisoner ceases to struggle, it is probably not because it has at
last come to understand the situation, but because it is discouraged. It is
checked, but not enlightened. Even so careful an
observer as Gilbert White credits the swallow with an act of judgment to which
it is not entitled. He says that in order that the mud nest may not advance too
rapidly and so fall of its own weight, the bird works at it only in the
morning, and plays and feeds the rest of the day, thus giving the mud a chance
to harden. Had not the genial parson observed that this is the practice of all
birds during nest-building — that they work in the early morning hours and feed
and amuse themselves the rest of the day? In the case of the mud-builders, this
interim of course gives the mud a chance to harden, but are we justified in
crediting them with this forethought? Such skill and
intelligence as a bird seems to display in the building of its nest, and yet
at times such stupidity! I have known a phoebe-bird to start four nests at
once, and work more or less upon all of them. She had deserted the ancestral
sites under the shelving rocks and come to a new porch, upon the plate of which
she started her four nests. She blundered because her race had had little or no
experience with porches. There were four or more places upon the plate just
alike, and whichever one of these she chanced to strike with her loaded beak
she regarded as the right one. Her instinct served her up to a certain point,
but it did not enable her to discriminate between those rafters. Where a little
original intelligence should have come into play she was deficient. Her
progenitors had built under rocks where there was little chance for mistakes of
this sort, and they had learned through ages of experience to blend the nest
with its surroundings, by the use of moss, the better to conceal it. My phoebe
brought her moss to the new timbers of the porch, where it had precisely the
opposite effect to what it had under the gray mossy rocks. I was amused at the
case of a robin that recently came to my knowledge. The bird built its nest in
the south end of a rude shed that covered a table at a railroad terminus upon
which a locomotive was frequently turned. When her end of the shed was turned
to the north she built another nest in the temporary south end, and as the
reversal of the shed ends continued from day to day, she soon had two nests
with two sets of eggs. When I last heard from her, she was consistently sitting
on that particular nest which happened to be for the time being in the end of
the shed facing toward the south. The bewildered bird evidently had had no
experience with the tricks of turn-tables! An intelligent man
once told me that crabs could reason, and this was his proof: In hunting for
crabs in shallow water, he found one that had just cast its shell, but the crab
put up just as brave a fight as ever, though of course it was powerless to
inflict any pain; as soon as the creature found that its bluff game did not
work, it offered no further resistance. Now I should as soon say a wasp
reasoned because a stingless drone, or male, when you capture him, will make
all the motions with its body, curving and thrusting, that its sting-equipped
fellows do. This action is from an inherited instinct, and is purely
automatic. The wasp is not putting up a bluff game; it is really trying to sting
you, but has not the weapon. The shell-less crab quickly reacts at your
approach, as is its nature to do, and then quickly ceases its defense because
in its enfeebled condition the impulse of defense is feeble also. Its surrender
was on physiological, not upon rational grounds. Thus do we without
thinking impute the higher faculties to even the lowest forms of animal life.
Much in our own lives is purely automatic — the quick reaction to appropriate
stimuli, as when we ward off a blow, or dodge a missile, or make ourselves
agreeable to the opposite sex; and much also is inherited or unconsciously
imitative. Because man, then,
is half animal, shall we say that the animal is half man? This seems to be the
logic of some people. The animal man, while retaining much of his animality,
has evolved from it higher faculties and attributes, while our four-footed
kindred have not thus progressed. Man is undoubtedly of animal origin, but his rise occurred when the principle of variation was much more active, when the forms and forces of nature were much more youthful and plastic, when the seething and fermenting of the vital fluids were at a high pitch in the far past, and it was high tide with the creative impulse. The world is aging, and, no doubt, the power of initiative in Nature is becoming less and less. I think it safe to say that the worm no longer aspires to be man. |