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 peck 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.
X
A PINCH OF SALT
Probably I have become unusually cautious of late about accepting
offhand all I read in print on subjects of natural history. I take
much of it with a liberal pinch of salt. Newspaper reading tends to
make one cautious--and who does not read newspapers in these days? One
of my critics says, apropos of certain recent strictures of mine upon
some current nature writers, that I discredit whatever I have not
myself seen; that I belong to that class of observers "whose
view-point is narrowed to the limit of their own personal experience."
This were a grievous fault if it were true, so much we have to take
upon trust in natural history as well as in other history, and in life
in general. "Mr. Burroughs might have remembered," says another critic
discussing the same subject, "that nobody has seen quite so many
things as everybody." How true! If I have ever been guilty of denying
the truth of what everybody has seen, my critic has just ground for
complaint. I was conscious, in the paper referred to,[4] of denying
only the truth of certain things that one man alone had reported
having seen,--things so at variance not only with my own observations,
but with those of all other observers and with the fundamental
principles of animal psychology, that my "will to believe," always
easy to move, balked and refused to take a step.
[4] _Atlantic Monthly_, March, 1903.
In matters of belief in any field, it is certain that the scientific
method, the method of proof, is not of equal favor with all minds.
Some persons believe what they can or must, others what they would.
One person accepts what agrees with his reason and experience, another
what is agreeable to his or her fancy. The grounds of probability
count much with me; the tone and quality of the witness count for
much. Does he ring true? Is his eye single? Does he see out of the
back of his head?--that is, does he see on more than one side of a
thing? Is he in love with the truth, or with the strange, the bizarre?
Last of all, my own experience comes in to correct or to modify the
observations of others. If what you report is antecedently improbable,
I shall want concrete proof before accepting it, and I shall
cross-question your witness sharply. If you tell me you have seen
apples and acorns, or pears and plums, growing upon the same tree, I
shall discredit you. The thing has never been known and is contrary to
nature. But if you tell me you have seen a peach tree bearing
nectarines, or have known a nectarine-stone to produce a peach tree, I
shall still want to cross-question you sharply, but I may believe
you. Such things have happened. Or if you tell me that you have seen
an old doe with horns, or a hen with spurs, or a male bird incubating
and singing on the nest, unusual as the last occurrence is, I shall
not dispute you. I will concede that you may have seen a white crow or
a white blackbird or a white robin, or a black chipmunk or a black red
squirrel, and many other departures from the usual in animal life; but
I cannot share the conviction of the man who told me he had seen a red
squirrel curing rye before storing it up in its den, or of the writer
who believes the fox will ride upon the back of a sheep to escape the
hound, or of another writer that he has seen the blue heron chumming
for fish. Even if you aver that you have seen a woodpecker running
down the trunk of a tree as well as up, I shall be sure you have not
seen correctly. It is the nuthatch and not the woodpecker that hops up
and down and around the trees. It is easy to transcend any man's
experience; not so easy to transcend his reason. "Nobody has seen so
many things as everybody," yet a dozen men cannot see any farther than
one, and the truth is not often a matter of majorities. If you tell me
any incident in the life of bird or beast that implies the possession
of what we mean by reason, I shall be very skeptical.
Am I guilty, then, as has been charged, of preferring the deductive
method of reasoning to the more modern and more scientific inductive
method? But I doubt if the inductive method would avail one in trying
to prove that the old cow really jumped over the moon. We do deny
certain things upon general principles, and affirm others. I do not
believe that a rooster ever laid an egg, or that a male tiger ever
gave milk. If your alleged fact contradicts fundamental principles, I
shall beware of it; if it contradicts universal experience, I shall
probe it thoroughly. A college professor wrote me that he had seen a
crow blackbird catch a small fish and fly away with it in its beak.
Now I have never seen anything of the kind, but I know of no principle
upon which I should feel disposed to question the truth of such an
assertion. I have myself seen a crow blackbird kill an English
sparrow. Both proceedings I think are very unusual, but neither is
antecedently improbable. If the professor had said that he saw the
blackbird dive head first into the water for the fish, after the
manner of the kingfisher, I should have been very skeptical. He only
saw the bird rise up from the edge of the water with the wriggling
fish in its mouth. It had doubtless seized it in shallow water near
the shore. But I should discredit upon general principles the
statement of the woman who related with much detail how she and her
whole family had seen a pair "of small brown birds" carry their
half-fledged young from their nest in a low bush, where there was
danger from cats, to a new nest which they had just finished in the
top of a near-by tree! Could any person who knows the birds credit
such a tale? The bank-teller throws out the counterfeit coin or bill
because his practiced eye and touch detect the fraud at once. On
similar grounds the experienced observer rejects all such stories as
the above. Darwin quotes an authority for the statement that our
ruffed grouse makes its drumming sound by striking its wings together
over its back. A recent writer says the sound is not made with the
wings at all, but is made with the voice, just as a rooster crows.
Every woodsman knows that neither statement is true, and he knows it,
not on general principles, but from experience--he has seen the grouse
drum.
Birds that are not flycatchers sometimes take insects in the air; they
do it clumsily, but they get the bug. On the other hand, flycatchers
sometimes eat fruit. I have seen the kingbird carry off raspberries.
All such facts are matters of observation. In the search for truth we
employ both the deductive and the inductive methods; we deduce
principles from facts, and we test alleged facts by principles.
The other day an intelligent woman told me this about a canary-bird:
The bird had a nest with young in the corner of her cage; near by were
some other birds in a cage--I forget what they were; they had a full
view of all the domestic affairs of the canary. This publicity she
evidently did not like, for she tore out of the paper that covered the
bottom of her cage a piece as large as one's hand and wove it into the
wires so as to make a screen against her inquisitive neighbors. My
informant evidently believed this story. It was agreeable to her
fancies and feelings. But see the difficulties in the way. How could
the bird with its beak tear out a broad piece of paper? then, how
could it weave it into the wires of its cage? Furthermore, the family
of birds to which the canary belongs are not weavers; they build
cup-shaped nests, and they have had no use for screens or covers, and
they never have made them. Just what was the truth about the matter I
cannot say, but if we know anything about animal psychology, we know
that was not the truth. It is always risky to attribute to an animal
any act its ancestors could not have performed.
Again, things are reported as facts that are not so much contrary to
reason as contrary to all experience, and with these, too, I have my
difficulties. A recent writer upon our wild life says he has
discovered that the cowbird watches over its young and assists the
foster-parents in providing food for them--an observation so contrary
to all that we know of parasitical birds, both at home and abroad,
that no real observer can credit the statement. Our cowbird has been
under observation for a hundred years or more; every dweller in the
country must see one or more young cowbirds being fed by their
foster-parents every season, yet no competent observer has ever
reported any care of the young bird by its real parent. If this were
true, it would make the cowbird only half parasitical--an unheard-of
phenomenon.