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Why Language Is All Thumbs
Toolmaking not only resulted in tools, but also the reconfiguration of our brains so they comprehended the world on the same terms as our toolmaking hands interacted with it. With mirror neurons, something entirely new entered the world: memes--a far more effective and speedy method for pooling knowledge and passing it around than the old genetic way.
Excerpted from Thumbs,
Toes, and Tears, Walker & Co.
2006. Published on KurzweilAI.net March 4, 2008.
Reprinted with permission.
Prologue
We are—all of us—freaks of nature. We don’t generally
see ourselves this way, of course. After all, being human, what
could be more ordinary than a human being? But it turns out that
our personal (and biased) impressions that we are unremarkable simply
don’t stand up against the plain, objective facts. The way
we walk, for example, teetering on long, paired stilts of articulated
bone, is unique among mammals, and as preposterous in its way as
elephant trunks and platypus feet. We also communicate by tossing
oddly intricate noises at one another, which somehow carry complex
packages of feeling, thought, and information. We share and understand
these sounds as if they were scents drifting on the wind, and our
minds special noses that sniff the fragrance of their meaning. Using
them we are able to change one another’s minds, even bring
one another to tears. We also invent, to the point of being dangerous,
incessantly bending the things, living and otherwise, around us
to our own ends. Because of this habit, we have, for better or worse,
created national economies, erected the pyramids of Giza and Chichén
Itzá, fashioned exquisite art, sculpture, and music, invented
the steam engine, moon rockets, the digital computer, stealth bombers,
and “weaponized” diseases. Nothing on the planet seems
to escape our urge to remake it. These days we are even tailoring
genes to remake ourselves.
This book is about how we became the strange creatures we are,
and why we do these peculiarly human things. It wonders what makes
us cry, why we fall in love, invent, deceive, laugh uproariously
with close friends, and kiss the ones we care about. It asks what
evolutionary twists and turns set in motion events that made the
symphonies of Mozart, the insights and art of Leonardo, the drama,
humor, and poetry of Shakespeare possible, not to mention bad soap
operas, Hollywood movies, and London musicals. It speculates on
why chimpanzees, despite sharing so much of our DNA, do not reflect
upon the meaning of life, or if they do, why they haven’t
so far shared their insights. In the end it wonders how you became
you and how our species became, of all the species it could have
become, the thoroughly unprecedented one it is.
Human beings are insatiably curious, especially when it comes
to the subject of ourselves. This is not a new insight. Philosophers,
poets, theologians, and scientists from Plato to Darwin, St. Augustine
to Freud have already penned volumes about our humanness that bow
endless rows of the sturdiest library shelves. You might ask, if
these thinkers have fallen gasping to the mat trying to wrestle
these questions into submission, why this book should have any better
luck. The simple answer is that today we have far more solid information
to work with.
During the past decade enormous strides have been made in two
broad scientific fields: genetics and neurobiology. Advances in
genetics are helping us gain insights into the way all living things
evolve and develop. Each of us has come to exist in the unique form
we do because of the combinations of genes that our parents passed
along. You are, to a large degree, the person you are because of
the messages these genes sent, and continue to send, to the ten
thousand trillion cells that have assembled just so to form you.
Hardly a day goes by without some news about a remarkable discovery
that further illuminates the molecular machinery of the DNA that
makes life possible.
The other field is brain research. Being a human being (as opposed
to a wasp or a fruit fly), all of your behaviors and actions are
not dictated by your genes alone. Your brain holds many of the secrets
that make humans human. Genes may be outrageously complicated, but
the human brain makes our genetic code look like the crayon drawings
of a four-year-old. Though it weighs a mere three pounds, it consists
of a hundred billion neurons, each of which is connected in a thousand
different ways to the other neurons around it. This means that every
waking moment your brain is linked along a hundred trillion separate
paths, trafficking in thought and insight, processing great streams
of sensory input, running the complex plumbing of your body, generating
(but not always resolving) all of your colliding and conflicting
emotions, conscious and unconscious. These connections, by one estimate,
make your possible states of mind during the course of your life
greater than all of the electrons and protons in the universe. Given
the immensity of this number, you are never likely to think all
of the thoughts you are actually capable of thinking, nor feel every
possible feeling. Nevertheless, each shining day we give it a try.
Over the past decade scientists have been developing ways to scan
and reveal in increasingly refined detail how our brains are constructed
and operate. They are far from resolving its mysteries, but we know
much more today about its behavior than we did even a short time
ago. Positron Emission Tomography (PET) scanning and FMRI (Functional
Magnetic Resonance Imaging) are revealing “movies” of
our thoughts, or more precisely the flow of chemicals in the brain
as we think and feel. Today we have a far better understanding of
how language, laughter, and thought play themselves out in the brain
than we did as recently as the turn of the twenty-first century.
Right now the resolution of these movies is cellular, but they will
soon reveal the brain at a molecular level, making the reading of
minds much more than a parlor trick.
Scientists also keep nibbling away at the mysterious edges of
paleoanthropology, psychology, physiology, sociology, and computer
science, to mention only a handful, shedding light bit by bit on
the special brand of behaviors we call human. In other words, we
remain largely unknown to ourselves, but we are making impressive
progress.
.
. .
How did we become human beings? All living things are unique.
The forces that drive evolution make them so, honing each down to
the razor edge of itself, providing it with a handful of qualities
that distinguish it as the only animal of its kind. The elephant
has its trunk. Bombardier beetles manufacture and precisely shoot
boiling hot toxic chemicals from their tails. Peregrine falcons
have wings that propel them unerringly through the air at seventy
miles an hour to their catch. These traits define these creatures
and determine the way they act. But what unique traits shape and
define us? I have whittled it down to six, each unique to our kind:
our big toes, our thumbs, our uniquely shaped pharynx and throat,
laughter, tears, and kissing. How, you may ask, can something as
common as a big toe, as silly as laughter, or as obvious as a thumb,
possibly have anything to do with our ability to invent writing,
express joy, fall in love, or bring forth the genius of ancestral
China? What could they have to say about rockets and radio, symphonies,
computer chips, tragedy, or the spellbinding art of the Sistine
Chapel? Just this.
The origin of all these human accomplishments can be traced to
these traits, each of which marks a fork in the evolutionary road
where we went one way and the rest of the animal kingdom went the
other, opening small passageways on the peculiar geography of the
human heart and mind, marking trailheads that lead to the tangled
outback of what makes us tick. Take the knobby big toes we find
at the ends of our feet. If they hadn’t begun to straighten
and strengthen more than five million years ago our ancestors would
never have been able to stand upright, and their front feet would
never have been freed to become hands. And if our hands had not
been freed we would not have evolved the opposed and specialized
thumbs we have, which made the first tools possible.
Both our toes and thumbs are linked to the third trait—our
unusual throats and the uniquely shaped pharynx inside, which enables
us to make more precise sounds than any animal. Standing up straightened
and elongated our throats so that our voice box dropped. In time
that made speech possible, but we also needed a brain that could
generate the complex mental constructions that language and speech
demand. Because toolmaking required a brain that could manipulate
objects, it supplied the neural foundations for logic, syntax, and
grammar so that eventually it could not only take objects and arrange
them in an orderly manner, it also could conceive ideas for our
pharynx to transform into the sound symbols we call words and organize
them so they made sense as well.
A mind capable of language is also a self-aware mind. Consciousness
melded our old primal drives with our newly evolved intelligence
in entirely unexpected ways that even language couldn’t successfully
articulate. This explains the origins of laughter, kissing, and
crying. Though we can glimpse their origins in the hoots, calls,
and ancient behaviors of our primate cousins, no other species carries
these particular arrows in the quivers they use to communicate.
.
. .
Some may argue that we cannot possibly be reduced to six of anything.
And some may argue that these traits are not unique to us. Kangaroos
stand upright, after all. And dogs whimper and whine. And don’t
chimpanzees pucker and smack their lips? Yes, but kangaroos hop,
they don’t stride; dogs do not cry tears of sorrow or joy
or pride. In fact, they don’t cry any tears at all. No other
animal does, not even elephants, contrary to some apocryphal stories.
And while chimps can be trained to kiss, they do not naturally climb,
during their adolescence, into the backseats of Chevrolets, or anything
else for that matter, to neck.
The larger point is that the extraordinary abilities and behaviors
that define us—for better or worse—as a species come
from somewhere, and if we keep asking, “where, how, why ...
” enough, we arrive at their roots. The investigation of one
illuminates the other, and together, in the peculiar arithmetic
of evolution, they eventually add up to the strange, astonishing,
and perplexing creatures we are. Maybe the point isn’t so
much to pin ourselves beneath the unforgiving glass of a microscope
to arrive at definitive and irrefutable answers. We are far too
complex a race to be reduced to the sum of so many split hairs.
Maybe the important thing is to simply keep asking interesting questions
and follow where the answers take us. As it turns out, they take
us to some remarkable and fascinating places.
. . .
Why Language Is All Thumbs
From
Chapter 3, "Mothers of Invention"
Because we have only two hands, rather than, say, eight tentacles, like an octopus,
we manipulate objects in an ordered sequence, not all at once. That
means to consciously do “A” before “B” and
“B” before “C,” we have to focus. You don’t
absentmindedly build a bow, or shape an arrow, or design a steam
engine. It requires intention and concentration. Anyone who has
struggled with assembling furniture at home knows that if B does
not follow after A and C upon B, things have a way of falling apart.
If scientists such as Lakoff, Johnson, and Greenfield are right, we manipulate
thoughts the way we do because our hands once learned to shape sticks,
stones, and animal skins into tools. Nouns became the equivalents
of objects, verbs represented actions, and we (or our hands) took
on the role of a sentence’s subject.
To ancestors like Handy Man, the physical grammar of cracking open
a femur to eat the marrow inside might have gone something like,
“Hit bone (with) stone.” He might not have had any words—any
mental symbols—to attach to these objects or actions, but
the pattern of using one thing to affect another would have been
part of his physical experience. There was no way around it. If
you pick up a stone to strike a bone, certain actions must unfold
in a certain sequence for the whole business to work out. The brain
must consciously conceive and act on that sequence, or the bone
and stone will forever sit there, and never the twain shall meet.
And any ape that spends his day gazing at a rock and bone, doing
nothing, will never eat an ounce of marrow, and certainly won’t
live long enough to pass his genes along. Animals like these, as
scientists like to say, “get selected out.”
The unavoidable conclusion here is that toolmaking not only resulted in tools,
but also in the reconfiguration of our brains so they comprehended
the world on the same terms as our toolmaking hands interacted with
it. The physical conversation our marionette fingers were having
with the objects around us was shaping the way our brain organized
and thought about everything. The hand speaks to the brain as surely
as the brain speaks to the hand. Art, or at least craft, was beginning to imitate life, and the rudiments of language
and complex human thought were sprouting from the sense-able, concrete
sequences of that life.
.
. .
In 1996, Vittorio Gallese, Giacomo Rizzolatti, and their colleagues at the University
of Parma in Italy inadvertently discovered the strange and mysterious
ways in which evolution works. They were recording signals transmitted
from neurons in an area of the brains of macaque monkeys called
the F5 region. This is a specific sector of the frontal lobes that
sits among a larger area of the brain that deals with making and
anticipating movements called, fittingly, the premotor cortex.
The scientific team already knew that F5 neurons fired when monkeys performed
specific goal-oriented tasks with their hands or mouths—picking
up a peanut and then holding it, for example. But for this series
of tests they wanted to see if the F5 neurons acted any differently
when the objects themselves were different. Did it matter, they
wondered, if a monkey was picking up a peanut rather than a slice
of apple?
It was while they were performing this routine experiment that they noticed something
odd. When a macaque watched a researcher’s hand pick up an
object and bring it close to his mouth, the sensors connected to
the monkey’s brain indicated that neurons in its F5 region
were firing. They didn’t activate when the monkeys simply
saw the objects sitting there, only—and this was what was
so unusual—when the monkey watched researchers pick them up,
or when the monkeys themselves picked them up.
The implications of this are enormous. If the same neurons were firing in the
monkeys’ brains when they watched the action, it meant they
were playing out what they were seeing before them inside their
own brain— their mind’s eye—just as if they were
doing it themselves. They were mentally “mirroring”
the physical action. You could also say that in a rudimentary way
they were imagining they were doing the action; reliving, neuron by firing neuron, the experiences of others—in
effect, putting themselves in the shoes of the researchers they
were watching. They were experiencing a form of empathy that itself
required a kind of imagination.
The ignition of F5 neurons made these seemingly simple gestures and maneuvers
a form of communication far more powerful than any hoot, grunt,
or howl. After all, if the monkey was mentally picturing the actions
of the researcher, it was also quite possibly remembering and learning
it. Monkey see, monkey do.
If you look hard, you can catch glimpses of early conscious communication on
all sides of this. Imagine two habiline creatures—a parent
and a child—sitting in their small, lakeside camp two million
years ago, smoke billowing from the enormous volcanoes at their
backs. They have roughly twice the neuronal wetware of the average
chimp today (and certainly more than a macaque monkey), so their
intelligence is far from trivial. On the other hand, they still
can’t speak, so their ability to share what is on their minds
is limited, even though they undoubtedly have far more to communicate
than any of the other animals around them.
Now imagine the parent is making a simple tool, like those that Nicholas Toth
and his colleagues experimented with. The child watches intently.
Simply by observing, the same neurons—her mirror neurons—are
firing in her head that are firing in her parent’s. And so
when she attempts to repeat the action she has been watching, she
can call upon those fired neurons to guide her hands to do something
she has never actually done before but has imagined doing.
For his part, when the parent strikes flint against the rock, he is silently
talking to the watching child. He is saying, with his hands, “This
is how you make this thing. You hold this large rock like this and
strike it with this small rock just so.” You can see him holding
up the sharp sliver of flint that the blow has created. “See,
now you have a knife.” And then next, he may carve the skin
off a carcass, taking the “conversation” in a new direction.
The entire time the child is “listening.” Neither parent nor daughter
have any language; not a single word they can exchange, not even
a concept of words, only the looks on their faces, the expressions
in their eyes, the gestures they make with their hands as they manipulate
and exchange the rocks and flint. But a lot of information is traveling
back and forth between their two minds. In a very real sense they
are conversing.
This apparent connection between conversation and manipulation is more than metaphorical.
More recent research, built on Gallese’s and Rizzolatti’s
original discovery, has revealed that the F5 region in macaque monkeys
is an analog for areas in our own brain essential for generating
human language and speech (not necessarily the same thing, as we
shall see). We know this partly because a few years after the discovery
of mirror neurons, Rizzolatti and another researcher, Scott Grafton,
found that when humans watch someone handle objects, a region of
the brain called the superior temporal sulcus, which sits directly
behind the left temple, activates and mirrors what they see. This
surprised scientists because they had long thought that this part
of the brain existed primarily to send the signals to Broca’s
area that generate speech. Now it appeared Broca’s area was
handling other jobs as well, or deeper ones. It not only sent signals
to the muscles that generated speech, it sent the signals to hands
and arms that enabled the precise manipulation of objects.
Rizzolatti thinks this fusion of objects and imagination, gestures and words
provides a glimpse into the genesis of language. Mirror neurons
might be the primal wetware that enabled our ancestors to transform
the common ground of doing and making into the earliest forms of
conscious communication. F5, or something like it, might very well
have been the bud from which Broca’s area—a cornerstone
of human language—blossomed.
The Insights of Dr. Broca
How we actually generate language is a mystery, but we know that
we can’t do it if a part of the brain known as Broca’s
area, named for the brilliant French doctor and anatomist Pierre
Paul Broca, who discovered it, doesn’t function properly.
Broca first located this part of the brain when he performed an
autopsy in 1861 on a patient, known as Tan, who had died from
gangrene. The man was known as Tan because when he tried to speak
all he seemed capable of saying again and again was the word “tan.” This affliction
became known as Broca’s aphasia, and the autopsy revealed that there had
been damage to specific sections of the inferior frontal gyrus
in the left frontal lobe of the brain (roughly near the left temple).
Subsequent studies Broca and others performed confirmed that in
most people (left-handers usually being the exception) this is
the area of the brain that somehow takes the symbols our minds
create when we want to communicate, attaches sounds to them, and
then coordinates sending the signals to all of the muscles needed
to make the precise sounds we call speech (or in the case of those
who can’t speak, make the hand signals needed to communicate).
Brain scanning technology has confirmed Broca’s findings.
These areas of the brain “light up” when we generate
speech. Broca’s area is connected to Wernicke’s area
by a neural pathway called the arcuate fasciculus, and using these
two sectors of the brain, we handle most of the generation and
understanding of the spoken (or signed) word. Because Broca’s
area is so closely located next to areas of the brain associated
with mirror neurons and those sectors that control both facial
muscles and hand coordination, it may help explain how toolmaking,
gestures, and speech are connected.
With mirror neurons, something entirely
new had entered the world: a far more effective and speedy method
for pooling knowledge and passing it around than the old genetic
way. Ideas could now be shared between minds! And that sort of knowledge-pooling,
as Darwin observed, would have seriously improved the chances of
a troop’s, a family’s, or an individual’s survival.
As he put it, “the plainest self-interest, without the assistance
of much reasoning power, would prompt the other members [of a tribe]
to imitate him; and all would thus profit. ... If the invention were an important one, the tribe would increase in number, spread
and supplant other tribes.”
This means that two astounding advances were unfolding during
Homo habilis' brief stay on Earth. First, entirely new knowledge
was being intentionally generated out of the brain of a single creature.
Toolmaking marked the birth of invention. Second, knowledge could
now be duplicated and relocated to other minds; it was no longer
doomed to die with the brain that conceived it. Just as the evolution
of DNA made it possible for a gene to be copied and shared from
one generation to the next, mirror neurons, and the new behaviors
they made possible, meant that an idea—a “meme,”
as Richard Dawkins has put it—could be copied and passed along
from one mind to the next. Conscious communication had emerged, even if only in an embryonic form, and in
its wake everything from gossip to oratory, mathematics to the laws
of Hammurabi, stand-up comedy to the computer code that sends probes
to the moons of Saturn would follow. We were building the scaffolding
for true human behavior, relationships, and, ultimately, that most
monumental of all human inventions: culture.
But how would our ancestors even begin to cross the chasm that
yawned between the first flint knives and the great edifices of
human endeavor we have erected since?
© 2006 Chip Walter
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