can. They pick up words for themselves. They talk with one another;
and when they don’t know the word for something they want to say,
they make one up. Don’t you remember various words that you and your
playmates invented, that other people do not know the meaning of? In
short, we human beings have a talking instinct; just as birds have a
nest-building instinct, and squirrels an instinct for hiding nuts in
the ground.
So if we should take a lot of robin’s eggs, hatch them out in an
incubator, feed the little birds by hand and never let them see a
grown up bird or a nest, there is no doubt that when the proper time
came they would sing, build nests, and take care of their young,
much as if they had been brought up by their parents in the usual
manner. In the same way, if we should take a lot of tiny babies and
bring them up where they never heard a word of speech, there is
little doubt that when it became time for them to talk, they would
invent for themselves a language to talk with. Indeed, some people
think that the reason why there are so many different languages in
the world, hundreds and hundreds as there are, is because at various
times children have been lost, or all the old people of a tribe have
died, and the children having no one to teach them their parents’
tongue, have had to make up a new language for themselves.
But no animal could possibly do this. Whether because they lack this
strange talking instinct, or because they simply haven’t anything in
particular that they want to say, no group of animals has ever
invented a language, nor has any single animal ever learned to talk
our human speech. A parrot can utter words; a dog can understand
them. But somehow no creature except ourselves ever puts the two
together, and talks.
I don’t think we ever half realize what an advantage this being able
to talk is to us, nor how utterly helpless we should be without it.
Suppose for example you are lost in a strange city. You stop the
first passerby, and you say “I want to find such and such a street.”
“So many blocks up or down,” he answers, “so many to the right or
left”; and with one or two more simple questions from time to time,
there you are right on your doorstep.
But suppose your dog gets lost. He can not stop the next dog or man
he sees and say, “I belong to Mr. So-and-so on Such-and-such Street;
tell me how to get home.” All he can do is to look up into some
one’s face and whine; and that may mean equally well, “lam lost,” or
“I am hungry,” or “I want a drink,” or “The little boy that owns me
has gone into that house and I wish he’d hurry up and come out,” or
“I don’t like the place where I am living because there is a horrid
cat there that scratches me on the nose, and I wish I could go home
and live with you instead,” or “I know you have been in a meat
market, because I can smell the nice smell of the fresh meat, and I
wish I were going to have some for my dinner in place of dog biscuit
which I don’t like.”
All these ideas, and forty others like them, the dog would have to
express in precisely the same way, and leave to his hearer to guess
which one he might happen to mean this particular time. In fact,
about all the ideas that a dog can express are, “I want something
that I haven’t got,” “I am afraid I’m going to get something I don’t
want,” and “If somebody doesn’t look out, there’s going to be a very
dickens of a row here in about a minute.” What he may think beyond
these simple matters he has pretty much to keep to himself.
And did you ever think how extremely difficult it would be to learn
anything, lacking words to learn it with? You can tell the capitals
of the United States, or the chief rivers of Asia, or the kings of
England, because somebody who knew has told somebody else, and he
somebody else, until the information has at length filtered down to
you. Whatever you do not know and want to know, you can find out
from somebody who does know, either by asking directly or by looking
in a book where somebody has written it down. But a dog can find out
things only by seeing them for himself, and when he does find them
out, he has no way of telling any other dog anything about them.
No wonder that cow I was telling you about a short while ago was not
in the least surprised when her calf ripped apart and the hay fell
out. Why should she not think that all calves are stuffed with hay,
and are expected sooner or later to rip apart and provide hay for
their mammas’ supper? She has no way of finding out what calves are
made of inside. If you wanted to know, you would ask. She couldn’t.
I suppose a child going to school and asking questions at home and
getting them answered, as every child should, learns at least a
hundred times as fast as any animal can possibly learn. I suppose
too that a dog or cat, living in one place and doing about the same
things every day, learns in a year or two all that there is to be
known about his particular world, and so finds out nothing more all
the rest of his life. You learn for lessons something new every day,
you see new people, and visit new places, you have new things to
eat, and new clothes. But the animals always have the same clothes,
and the same things to eat. Most of them do not travel; if they do
sometimes make new friends, the new friends cannot tell them
anything. Think, then, how ignorant must be the rabbit shut up in
one pen, the cow confined to one pasture, the parrot always in the
same cage. They do the same things day after day; in a week they
have learned all there is to be known.
Of course, an animal cannot tell time nor count; for telling time
and counting require words. He cannot give names to anything, nor
remember anything by name, nor think about anything in words.
Indeed, it is pretty difficult, without words, to do any thinking at
all. We can learn, think, remember, plan, contrive, teach, ask
questions, answer them, because we have words to work with. The
animals have no words. Therefore, the wisest of them is like a child
of four.
XVIII
Something More About Speech and Thinking
We say commonly that we think with our brains. That is true; but it
is by no means the whole story. The brain has two halves, just
alike, exactly as the body has. In fact, the two sides of the brain
are even more precisely alike than the two hands.
Nevertheless, we do all our thinking with one side only. If we are
naturally right-handed persons, we do our thinking on the left side
of the head. If we are naturally left-handed, we do our thinking on
the right side. But we do not use both sides. Each half of the brain
governs the muscles of one side of the body; but the thinking is
done with one side only.
This very peculiar state of affairs is in some way or other
connected with our power of speech. The animals, who cannot use
words, do their thinking, so far as we know, equally on both sides
of their heads; and we have every reason to believe that if we did
not talk, we too should do our thinking with both sides.
Let us see if we cannot in part make out the reason for this
arrangement. Let us suppose you are using your mouth and tongue, not
to talk with, but to eat your breakfast. Each half of the brain, as
I have said, controls the muscles on one side of the body; and as I
dare say you have long ago been taught in school, a set of long
nerve fibers, like so many telephone lines, connects each muscle
with the proper region of the outer surface of the brain. You are,
we are supposing, at breakfast, and you take a bite of bread and
butter. At once, the two halves of the tongue telephone by way of
the nerves, each to its own side of the brain, “Something good to
eat, shall we chew and swallow?” Then each half-brain telephones
back, “Message received, stand by to chew, on signal; will call up
other side.” Then each side of the head rings up the other side and
says, “Bread and butter reported in my half the mouth; shall chew at
once. Are you ready to start? Go!” And away go the two sides of the
face working together.
Now of course I do not mean to say that this is literally what
occurs every time you attempt to do anything that requires both
sides of the body to act together. Nevertheless, something like this
really does happen. You know how a tiny baby cannot even look at the
same point with both eyes at once, but sends them straddling off,
one looking one way, the other another. It takes some days for the
two halves of the baby’s brain to learn to consult one another, and
to handle their two eyes in co-operation. So with any act that uses
two hands, or two feet, or a hand on one side of the body and a foot
on the other. The two halves of the brain have to call across to one
another, along certain nerve fibers which run back and forth between
the two, in order that the actions of the two sides of the body may
keep together. You can easily see that if one side of the brain
tried to open its side of the mouth, while the other side was trying
to shut its, you would probably have to start for school without
your breakfast.
Naturally, after the two brain halves have been living together for
a few years, growing up together in the same house, they learn to
work almost like one. Still this signaling back and forth does take
time. So long as we are merely eating, or walking, or shoveling
snow, the process goes on fast enough. But talking is a different
matter. When you are talking thirteen to the dozen, just as fast as
you can chatter, every several letter of every single word you utter
demands at least one change of position of tongue or lips or throat,
and generally of them all.
What would happen if the two halves of the brain had to stop to call
one another up and say, “Now I am on the point of starting to say
‘t’ with my half of the mouth. Are you ready with yours?” “Now I am
going to tuck on an ‘h.’ Are you ready with your side?” “Now go
ahead with the ‘e.’ Start.” It wouldn’t do at all. It’s altogether
too slow a way to get talking done. So by way of saving time, one
side of the brain has taken entire charge of the talking; for this,
one side only of the brain runs both sides of the mouth.
When we eat, then, both sides of the brain are in action. But when
we use the very same muscles for speaking, then we use one side of
the brain only. When we lift a weight with both hands, we signal to
the muscles from both halves of the brain. But when we play the
piano with both hands, the same side of the brain takes charge of
both. I am, for example, using a type-writer, and writing with both
hands. Only one half of my brain, however, has charge of the
writing. The other half simply side-tracks itself, stands aside, and
doesn’t meddle. But the minute I stop writing and start to put my
machine in its case, then the other half-brain switches on again,
and takes care of its side. If I should hurt my right hand, so that
I had to do all my writing with the left, the writing side of my
brain would still do all the writing, while the other side that
commonly manages my left hand would stand and look on. All these
very special, complex, rapid and difficult tasks, like talking,
writing, playing the piano, or running the type-writer, are done by
one side of the brain. The slow and easy things are done by both.
But the animals, who do not either talk or write or play musical
instruments, they use the two sides of their brains alike.
XIX
Why Most Of Us Are Right-Handed
We do our talking with one side of the brain only. But talking is
somewhat intimately connected with thinking. We ought to always, we
generally do, think before we speak; while much of our thinking, and
on the whole the most important part, consists in saying over words
to ourselves.
Speech and thinking, then, go so often together, that it becomes a
great convenience to get the thinking done also on one side of the
head only, and on the same side with the speech. It might have been
either side; it did happen to be the left. One cannot say why, any
more than why the heart should be on the left side and the liver on
the right, or why some snail shells curl one way and some the other.
But at any rate it is the left side.
Now I don’t know whether you have yet been taught in your school
physiology, if you have not yet you will be shortly, that the nerves
which run from the brain to various parts of the body, cross over to
the other side from the one on which they start. Thus the right side
of the brain controls the left side of the body; while the left side
of the brain controls the right side of the body.
But if the thinking is all done on the left side of the head, which
hand will act more quickly on the thought? Evidently, the right
hand; messages for that hand travel directly along the nerves,
crossing sides once. Therefore we are right-handed.
Some people, however, are born with the “speech center,” as it is
called, on the right side of the head instead of on the left. For
such persons the most direct path is to the left hand. These
persons, then, are naturally left-handed. The difference, therefore,
between a right-handed and a left-handed person is not so much in
the side of the body with which they have learned to act, as in the
side of the brain with which they have learned to think. But the
animals, who think on both sides alike, also use either forefoot
equally well, and are neither right nor left-handed.
This talking on one side of the brain has another curious result.
Did you ever stop to think why a right-handed batter stands with his
left side to the ball? Or why a driver of a horse sits on the right
hand end of the seat? Or why the engineer of a locomotive sits on
the right side of the cab, altho this position forces him to use his
left hand for the throttle valve? Or why you sight a gun or look
thru a spy-glass with the right eye? Or why you draw a bow with the
right hand on the string?
It is all on account of this same one-sided speech center. This has
made us right-handed; it has also made us right-eyed. We think much
in words; but we also think much about how things look. We think
most quickly concerning messages which come in on the thinking side
of the brain; and those are from the right eye, since the eye
nerves, like those from the hand, cross sides on the way. So hand
and eye and speech and thought all use the same side of the head;
and sight and thought and action follow one another most easily.
Being then right-eyed, we stand to bat, or sit to drive, or use gun
or bow or telescope, in the way which gives the better sight to the
better eye. But of course, naturally left-handed people are also
naturally left-eyed.
Some people, however, are as we say, ambidextrous; that is, they use
both hands about equally well, just as all animals do. Nobody,
however, is ever naturally ambidextrous. Sometimes the ambidexters
are people who have hurt the right hand, and had to learn to use the
left. More often they are persons naturally left-handed who have
been taught to use the right hand more than is natural in an effort
to make them right-handed, tho of course they really are just as
left-handed at ever, since no use of the other hand will change over
the speech center. But some ambidexters, oddly enough, are made so
by an injury to the sight of the right eye, if they were
right-handed to begin with, or to the left eye if they were
left-handed. Hand and eye have so often to work together and work
quickly, that one tends to use the hand on the side of the better
eye, even when that is the wrong side.
At any rate, tho it is an excellent plan to learn to do all heavy
work equally well on either side of the body and with either hand,
fine work and quick work and thinking work had better be done with
the hand that does it most naturally. This keeps writing, thinking,
speaking, memory, and the rest all close together, on one side of
the head, handy to one another, instead of scattering them about,
some on the wrong side of the body, some on the right.
XX
Where We Do Our Thinking
We think only on the left side of our heads—that is easy to say if
we are normal right-handed persons. If for any reason we have got to
thinking on the right side, that will, as I have explained, usually
result in making us left-handed.
Yet we do not use the whole of even one side of the brain. So far as
is known, we do not think at all with the front part of the head.
All our speaking and most of our thinking are done from a spot
hardly larger than a cart-wheel dollar, which lies on the side of
the head just above the left ear. At any rate, an injury to this
particular part of our brain puts a sudden stop to our ability to
think and speak.
When you put your left elbow on the table and lean your head on your
hand, your hand just about covers the only portion of the brain with
which you ever do any thinking at all; while only with the part that
lies directly under the middle of the palm, and is as I have said,
about the size of a silver dollar, do you ordinarily think very much
or hard. This thinking part of the brain lies on the outside, and is
just about as thick thru as the hand is.
But even this small thinking place in the brain is not all alike.
Directly over the ear, a place that you can almost cover with your
thumb, lies the most important part of all, the place where we
remember and handle words. At the bottom of this word spot, we
remember how words sound. An inch farther up and toward the back, we
remember how words look in print. A little farther up and forward
lies the “speech center,” from which, when we want to talk, we
direct the tongue and lips what to say. Thus we get our
word-hearing, our word-seeing, and our word-speaking centers close
together, so that when we speak we have close by and handy our
memory of what we have heard in words, and of what we have read.
Just below the place where we remember words, and a little forward
of it, lies the place where we remember other sounds which are not
words, such as the noises of bells and whistles, barking of dogs,
mewing of cats, all buzzings and creakings and gratings and
crashings, all laughing and crying. Every kind of sound which isn’t
either words or music is recognized and remembered here. Beyond this
spot, still farther forward and down, and just above the rear end of
the cheek-bone, is the place where we remember music. If we don’t
know anything about music, and can’t tell Yankee Doodle from Old
Hundred, then we don’t use this part of our brains at all. But if we
do know one tune from another, and know a good many to recognize
them when we hear them, here is where we do the knowing.
[Illustration: A right-handed person has all his thinking spots
on the left side of his brain.]
Back of the word-seeing part of the thinking spot, and reaching
pretty well round to the back of the head, lies the place where we
remember everything we see, except words written or in print. Above
the word-speaking part of the brain, or speech center, from which we
control the mouth, throat, lips, and tongue, which we use in
speaking, lie the various points from which we manage other parts of
the body. As you might expect, next the speech center lies the
center for the rest of the face and for the head and eyes. Above
that comes the center for the hand and arm. Still higher up, right
on the top of the head, comes the center for the legs. So whenever
we do anything with any part of the body, we have to signal the
proper muscles from the part of the brain that lies between the tip
of the ear and the top of the head. Close behind this region is the
spot where we feel everything that touches the skin; so that we can
make the movement and feel the results most handily.
So as you see, the surface of the brain is a sort of map or chart of
the entire body. Every muscle, every point on the skin, the eyes,
the ears, the nose, the tongue, every several organ which we
possess, has its own special spot on the surface of the brain,
somewhere above or behind the ear. Each half of the body is charted
on one side of the brain, a spot in one for each spot in the other.
But we who have to use these brains to think and remember with, as
well as to see and hear and feel with, and to control our muscles,
have chosen to do this thinking and remembering with the spot on the
left side of the head which corresponds to the muscles of the lips
and mouth and tongue, and to the eyes and ears and the right hand.
Thus we have everything convenient, all in one small spot on one
side of our heads, where we can get at everything with the least
trouble. But what the front part of the brain is for, is something
that nobody knows much about.
Certain very strange results follow from this practice of ours of
using only one side of the brain to think, remember, and speak with;
and using different parts of that for thinking and remembering about
different sorts of things. Once upon a time there was a workman who
was hit hard enough to break his skull, on the left side of his
head, pretty well round toward the back, and just over the spot
where, as I have explained, are stored up all the memories of things
seen. He seemed not seriously hurt; but when his wife came to see
him at the hospital, he did not know her. Neither did he know his
children nor his friends. In fact, he didn’t even know that they
were human beings. He had absolutely lost the memory of everything
that he had ever seen.
But the minute his wife spoke he knew her at once. Or if he could
feel of any familiar thing he knew what it was. All the while, he
could see perfectly well. His eyesight remained as good as ever, he
simply couldn’t remember that he had ever seen things before. The
plain seeing, he could do with either side of his head; and the left
side being hurt, he did it with the other. But the remembering that
he had seen the same thing before, he did with the left side only;
and when he could no more do it with that, he could not do it at
all. Yet his memory for sounds and the feeling of things was just as
good as ever; because the places where he did these sorts of
remembering were not under the place where he got hit. And the
moment the doctors lifted out the splinter of bone that was pressing
on his seeing-things spot, then he remembered wife, children,
friends, everything as before.
Here is another case, much like the first, and yet curiously
different: An educated woman, somewhat well along in years, went to
bed at night in ordinary health. During the night, however, a small
blood vessel burst and formed a tiny blood blister on the left side
of her brain, about an inch in front of the spot where, as I have
been telling, the workman was hit who couldn’t remember his wife
when he saw her. She had, in short, a sort of internal black eye,
just on the spot that she had been using for sixty years and more to
remember written and printed words.
She woke up in the morning, therefore, totally unable to read a
single word. She could see as well as ever, understand perfectly
every word said to her, speak and write without the least
difficulty—but she simply could not read. Give her a printed book,
she could count the letters in every word, draw them on paper, tell
which were tall, short, round, or square, see them in fact just as
well as before—but she no longer knew what they meant. It was
exactly as if she had never learned to read at all; and being much
too old to learn again, she never read another word as long as she
lived.
There is another accident which is so little uncommon that probably
every one who reads this book will some time in his life see an
example of it. This is a case where a blood vessel bursts on the
left side of the brain and wrecks the speech center. The person to
whom this happens, immediately forgets how to talk. If the blood
clot is small, so it presses upon the speech center and nothing
else, the victim of this sort of accident can read and write as
before, and understand all that is said to him. Oddly enough, too,
he can make any sound that he ever could, and repeat parrot-like any
words that he hears. But he cannot remember the meaning of words. He
is precisely like a man suddenly transported to a foreign country
where they speak a language which he never heard. His own language
has become to him like Chinese.