Mission College Human and Non Human Primate Communication Essay

Topic:

In this essay, you will compare and contrast human language and the vocal communication of nonhuman primates. Specifically, you should analyze how the vocal communication systems of humans and nonhuman primates compare in terms of:

(1) production mechanism (anatomy and process);

(2) repertoires (types of signals and range of meanings that the signals convey); and

(3) underlying cognitive abilities (grammar, referentiality, intentionality, theory of mind, etc.).

Questions (1) and (2) should be discussed briefly; your primary focus is question (3), which should take up a majority of both space and emphasis in your essay. One of the key questions in the study of human language considers which aspects of language are uniquely human and which may be considered part of our primate heritage (see Zuberbuhler 2012). This is a difficult question, on which there is no consensus in the scientific community and you will not resolve the issue yourself. Your focus here should be on the cognitive aspects of communication.

Regarding question (2), we take it as given that human languages are capable of producing an unlimited variety of utterances and conveying a full range of meanings, intentions, and emotions (cf. Pinker, Ch. 2). As for (3), you can use what you know about your own language use and experiences to explore human cognition and communication. However, do not go into a lengthy discussion of human language; the focus should be on nonhuman primates for these questions.

Guidelines:

Essays are assessed not only for content, but also for grammar, clarity, conciseness, and coherence. Strive to make your essays accurate, relevant and organized, and use academic English. Your writing should demonstrate an understanding of key scientific terms related to sound and communication, with accurate use of relevant technical terms. You might think of this as writing a short article directed towards an educated layperson, and it should read as a prose essay, not a lab report outlining observations. The purpose is to assess your writing skills in addition to your understanding of the material presented in class.

For source material, you may draw on a mix of course lectures, videos, and assigned readings, but

to earn full credit, you must include material from (and properly cite) at least

two

articles from the course readings.

You are, of course, welcome to use more than two course readings. No outside sources are required, though you are certainly welcome to draw on other research materials if you like. There is no need to provide citations for material you draw from lectures, unless the material originated from one of the readings or videos. Properly cite both in-text and at the end of the essay these and any other data drawn from course readings and videos. You may use either MLA or APA style citation as long as you are consistent in the citation format. If you do use additional sources, be sure to cite them as well. As with any academic writing, the ideas you present in your paper if they are from a specific source (other than ideas you came up with yourself) you

must

cite them both

in-text

(within the body of your paper) and

at the end of the essay

in a reference list.

Formatting and Submission

Provide your own original, descriptive title for your essay. (Do not simply copy and paste “Vocal Communication of Humans and Nonhuman Primates”).

Your essay must be a minimum of 1200 words long, but no longer than 1500 words. Include the word count in your document.

Document formatting should use a 12-point font, double-spaced, have 1-inch margins on all sides, and be saved in either doc/.docx or .pdf format only. Documents in shared drives will not be accepted.

The essay must be uploaded to Turnitin before the due date/time.

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Grammar Genes
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Language Organs and Grammar Genes
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Susie invited her and I to the party. It is all a matter of heredity.
This we can handle.
A single dominant gene, the biologists believe, controls
the ability to Learn grammar. A child who says “them marbles
is mine” is not necessarily stupid. He has all his marbles. The
child is simply a little shon on chromosomes.
It boggles the mind. Before long the researchers will iso­
late the gene that controls spelling … [the column continues]
… neatness…. The read-a-book gene … a gene to turn
down the boom box … another to turn off the “IV … polite­
ness … chores … homework …
Bombeck wrote:
POOR GllAMMAR? IT AIlE IN THE GENES
“Ability to Learn Grammar Laid to Gene by Researcher.” This 1992
headline appeared not in a supermarket tabloid but in an Associated
Press news story, based on a report at the annual meeting of the prin­
cipal scientific association in the United States. The report had sum­
marized evidence that Specific Language Impairment runs in families,
focusing on the British family we met in Chapter 2 in which the inher­
itance pattern is particularly clear. The syndicated coLumnists James J.
Kilpatrick and Erma Bombeck were incredulous. Kilpatrick’s column
began:
BE’ITER GRAMMAR THROUGH GENETICS
Researchers made a stunning announcement the other
day at a meeting of the American Association for the Advance­
ment of Science. Are you ready? Genetic biologists have identi­
fied the grammar gene.
Yes! It appears from a news account that Steven Pinker of
MIT and Myrna Gopnik of McGill University have solved a
puzzle that has baffled teachers of English for years. Some
pupils master grammar with no more than a few moans of pro­
test. Others, given the same instruction, persist in saying that
It was not much of a surprise to read that kids who are
unable to learn grammar are missing a dominant gene…. At
one time in his career, my husband taught high school English.
He had 37 grammar-gene deficients in his class at one time.
What do you think the odds of that happening are? They didn’t
have a clue where they were. A comma could have been a pet­
roglyph. A subjective complement was something you said to a
friend when her hair came out right. A dangling participle was
not their problem….
Where is that class of young people today, you ask? They
are all major sports figures, rock stars and television personali­
ties who make millions spewing out words such as “bummer,”
“radical” and “awesome” and thinking they are complete sen­
tences.
The syndicated columns, third-hand newspaper stories, editorial
cartoons, and radio shows following the symposium gave me a quick
education about how scientific discoveries get addled by journalists
working under deadline pressure. To set the record straight: the dis­
covery of the family with the inherited language disorder belongs to
Gopnik; the reponer who generously shared the credit with me was
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The Language Instinct
confused by the fact that I chaired the session and thus introduced
Gopnik to the audience. No grammar gene was identified; a defective
gene was inferred, from the way the syndrome runs in the family. A
single gene is thought to disrupt grammar, but that does not mean a
single gene controls grammar. (Removing the distributor wire pre­
vents a car from moving, but that does not mean a car is controlled
by its distributor wire.) And of course, what is disrupted is the ability
to converse normally in everyday English, not the ability to learn the
standard written dialect in school.
But even when they know the facts, many people share the col­
umnists’ incredulity. Could there really be a gene tied to something
as specific as grammar? The very idea is an assault on the deeply rooted
belief that the brain is a general-purpose learning device, void and
without form prior to experience of the surrounding culture. And if
there are grammar genes, what do they do? Build the grammar organ,
presumably-a metaphor, from Chomsky, that many find just as pre­
posterous.
But if there is a language instinct, it has to be embodied some­
where in the brain, and those brain circuits must have been prepared
for their role by the genes that built them. What kind of evidence
could show that there are genes that build parts of brains that control
grammar? The ever-expanding toolkit of the geneticist and neurobiol­
ogist is mostly useless. Most people do not want their brains impaled
by electrodes, injected with chemicals, rearranged by surgery, or
removed for slicing and staining. (As Woody Allen said, “The brain is
my second-favorite organ.”) So the biology of language remains
poorly understood. But accidents of nature and ingenious indirect
techniques have allowed neurolinguists to learn a surprising amount.
Let’s try to home in on the putative grammar gene, beginning with a
bird’s-eye view of the brain and zooming in on smaller and smaller
components.
We can narrow down our search at the outset by throwing away half
the brain. In 1861 the French physician Paul Broca dissected the brain
of an aphasic patienl who had been nicknamed “Tan” by hospital
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Language Organs and Grammar Genes
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305
workers because that was the only syllable he uttered. Broca discov­
ered a large cyst producing a lesion in Tan’s left hemisphere. The next
eight cases of aphasia he observed also had left-hemisphere lesions,
too many to be attributed to chance. Broca concluded that “the fac­
ulty for articulate language” resides in the left hemisphere.
In the 130 years since, Broca’s conclusion has been confirmed by
many kinds of evidence. Some of it comes from the convenient fact
that the right half of the body and of perceptual space is controlled by
the left hemisphere of the brain and vice versa. Many people with
aphasia suffer weakness or paralysis on the right side, including Tan
and the recovered aphasic of Chapter 2, who awoke thinking that he
had slept on his right arm. The link is summed up in Psalms 137:5-6:
If! forget thee, 0 Jerusalem, let my right hand forget her cun­
ning.
If I do not remember thee, let my tongue cleave to the roof of
my mouth.
Normal people reCOgnize words more accurately when the words are
flashed to the right side of their visual field than when they are flashed
to the left, even when the language is Hebrew, which is written from
right to left. When different words are presented simultaneously to
the two ears, the person can make out the word cOming into the right
ear better. In some cases of otherwise incurable epilepsy, surgeons
disconnect the two cerebral hemispheres by cutting the bundle of
fibers running between them. After surgery the patients live com­
pletely normal lives, except for a subtlety discovered by the neurosci­
entist Michael Gazzaniga: when the patients are kept still, they can
describe events taking place in their right visual field and can name
objects in their right hand, but cannot describe events taking place in
their left visual field or name objects placed in their left hand (though
the right hemisphere can display its awareness of those events by non­
verbal means like gesturing and pointing). The left half of their world
has been disconnected from their language cente~.
When neuroscientists look directly at the brain, using a variety of
techniques, they can actually see language in action in the left hemi­
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The Language Instinct
sphere. The anatomy of the normal brain-its bulges and creases-is
slightly asymmetrical. In some of the regions associated with lan­
guage, the differences are large enough to be seen with the naked
eye. Computerized Axial Tomography (CT or CAT) and Magnetic
Resonance Imaging (MRI) use a computer algorithm to reconstruct
a picture of the living brain in cross-section. Aphasics’ brains almost
always show lesions in the left hemisphere. Neurologists can tempo­
rarily paralyze one hemisphere by injecting sodium amytal into the
carotid artery. A patient with a sleeping right hemisphere can talk; a
patient with a sleeping left hemisphere cannot. During brain surgery,
patients can remain conscious under local anesthetic because the brain
has no pain receptors. The neurosurgeon Wilder Penfield found that
small electric shocks to certain parts of the left hemisphere could
silence the patient in mid-sentence. (Neurosurgeons do these manipu­
lations not· out of curiosity but to be sure that they are not cutting
out vital parts of the brain along with the diseased ones.) In a tech­
nique used on normal research subjects, electrodes are pasted allover
the scalp, and the subjects’ electroencephalograms (EEG’s) are
recorded as they read or hear words. There are recognizable jumps in
the electrical signal that are synchronized with each word, and they
are more prominent in the electrodes pasted on the left side of the
skull than in those on the right (though this finding is tricky to inter­
pret, because an electrical signal generated deep in one part of the
brain can radiate out of another part).
In a new technique called Positron Emission Tomography
(PET), a volunteer is injected with mildly radioactive glucose or water,
or inhales a radioactive gas, comparable in dosage to a chest X-ray,
and puts his head inside a ring of gamma-ray detectors. The parts
of the brain that are more active burn more glucose and have more
oxygenated blood sent their way. Computer algorithms can recon­
struct which parts of the brain are working harder from the pattern of
radiation that emanates from the head. An actual picture of metabolic
activity within a slice of the brain can be displayed in a computer­
generated photograph, with the more active areas showing up in
bright reds and yellows, the quiet areas in dark indigos. By subtracting
Language Organs and Grammar Genes
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307
an image ofthe brain when its owner is watching meaningless patterns
or listening to meaningless sounds from an image when the owner is
understanding words or speech, one can see which areas of the brain
“light up” during language processing. The hot spots, as expected,
are on the left side.
I
What exactly is engaging the left hemisphere? It is not merely
speechlike sounds, or wordlike shapes, or movements of the mouth,
but abstract language. Most aphasic people-Mr. Ford from Chapter
2, for example–can blowout candles and suck on straws, but their
writing suffers as much as their speech; this shows that it is not mouth
control but language control that is damaged. Some aphasics remain
fine singers, and many are superb at swearing. In perception, it has
long been known that tones are discriminated better when they are
played to the left ear, which is connected most strongly to the right
hemisphere. But this is only true if the tones are perceived as musical
sounds like hums; when the ears are Chinese or Thai and the same
tones are features of phonemes, the advantage is to the right ear and
the left hemisphere it feeds.
If a person is asked to shadow someone else’s speech (repeat it as
the talker is talking) and, simultaneously, to tap a finger to the right
or the left hand, the person has a harder time tapping with the right
finger than with the left, because the right finger competes with lan­
guage for the resources of the left hemisphere. Remarkably, the psy­
chologist Ursula Bellugi and her colleagues have shown that the same
thing happens when deaf people shadow one-handed signs in Ameri­
can Sign Language: they find it harder to tap with their right finger
than with their left finger. The gestures must be tying up the left
hemispheres, but it is not because they are gestures; it is because they
are linguistic gestures. When a person (either a signer or a speaker)
has to shadow a goodbye wave, a thumbs-up sign, or a meaningless
gesticulation, the fingers of the right hand and the left hand are
slowed down equally.
The study of aphasia in the deaf leads to a similar conclusion.
Deaf signers with damage to their left hemispheres suffer from forms
of sign aphasia that are virtually identical to the aphasia of hearing
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The Language Instinct
Language Organs and Grammar Genes
victims with similar lesions. For example, Mr. Ford’s sign-language
counterparts are unimpaired at nonlinguistic tasks that place similar
demands on the eyes and hands, such as gesturing, pantomiming, rec­
ognizing faces, and copying designs. Injuries to the right hemisphere
of deaf signers produce the opposite pattern: they remain flawless at
signing but have difficulty performing visuospatial tasks, just like hear­
ing patients with injured right hemispheres. It is a fascinating discov­
ery. The right hemisphere is known to specialize in visuospatial
abilities, so one might have expected that sign language, which
depends on visuospatial abilities, would be computed in the right
hemisphere. Bellugi’s findings show that language, whether by ear
and mouth or by eye and hand, is controlled by the left hemisphere.
The left hemisphere must be handling the abstract rules and trees
underlying language, the grammar and the dictionary and the anat­
omy of words, and not merely the sounds and the mouthings at the
surface.
Why is language so lopsided? A better question is, why is the rest of a
person so symmetrical? Symmetry is an inherently improbable
arrangement of matter. If you were to fill in the squares of an 8 X 8
checkerboard at random, the odds are less than one in a billion that
the pattern would be bilaterally symmetrical. The molecules oflife are
asymmetrical, as are most plants and many animals. Making a body
bilaterally symmetrical is difficult and expensive. Symmetry is so
demanding that among animals with a symmetrical design, any disease
or weakness can disrupt it. As a result, organisms from scorpion flies
to barn swallows to human beings find symmetry sexy (a sign of a fit
potential mate) and gross asymmetry a sign of deformity. There must
be something in an animal’s lifestyle that makes a symmetrical design
worth its price. The crucial lifestyle feature is mobility: the species with
bilaterally symmetrical body plans are the ones that are designed to
move in straight lines. The reasons are obvious. A creature with an
asymmetrical body would veer off in circles, and a creature with asym­
metrical sense organs would eccentrically monitor one side of its body
even though equally interesting things can happen on either side.
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309
Though locomoting organisms are symmetrical side-to-side, they are
not (apart from Dr. Dolittle’s Push-mi-pull-you) symmetrical front­
and-back. Thrusters apply force best in one direction, so it is easier to
build a vehicle that can move in one direction and tum than a vehicle
that can move equally well in forward and reverse (or that can scoot
offin any direction at all, like a flying saucer). Organisms are not sym­
metrical up-and-down because gravity makes up different from down.
The symmetry in sensory and motor organs is reflected in the
brain, most of which, at least in nonhumans, is dedicated to process­
ing sensation and programming action. The· brain is divided into maps
of visual, auditory, and motor space that literally reproduce the struc­
ture of real space: if you move over a small amount in the brain, you
find neurons that correspond to a neighboring region of the world as
the animal senses it. So a symmetrical body and a symmetrical percep­
tual world is controlled by a brain that is itself almost perfectly sym­
metrical.
No biologist has explained why the left brain controls right space
and vice versa. It took a psycholinguist, Marcel Kinsbourne, to come
up with the only speculation that is even remotely plausible. All bilat­
erally symmetrical invenebrates (worms, insects, and so on) have the
more straightforward arrangement in which the left side of the central
nervous system controls the left side of the body and the right side
controls the right side. Most likely, the invenebrate that was the
ancestor of the chordates (animals with a stiffening rod around their
spinal cords, including fish, amphibians, birds, reptiles, and mammals)
had this arrangement as well. But all the chordates have “contralat­
eral” control: right brain controls left body and left brain controls
right body. What could have led to the rewiring? Here is Kinsbourne’s
idea. Imagine that you are a creature with the left-brain-Ieft-body
arrangement. Now tum your head around to look behind you, a full
180 degrees back, like an owl. (Stop at 180 degrees; don’t go around
and around like the girl in The Exorcist.) Now imagine that your head
is stuck in that position. Your nerve cables have been given a half­
twist, so the left brain would control your right body and vice versa.
Now, Kinsbourne is not suggesting that some primordial rubber­
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The Language Instinct
necker literally got its head stuck, but that changes in the genetic
instructions for building the creature resulted in the half-twist during
embryonic development-a torsion that one can actually see happen­
ing during the development of snails and some flies. This may sound
like a perverse way to build an organism, but evolution does it all the
time, because it never works from a fresh drawing board but has to
tinker with what is already around. For example, our sadistically
designed S-shaped spines are the product of bending and straighten­
ing the arched backbones of our quadrupedal forebears. The Picas­
soesque face of the flounder was the product of warping the head of
a kind of fish that had opted to cling sideways to the ocean floor,
bringing around the eye that had been staring uselessly into the sand.
Since Kinsbourne’s hypothetical creature left no fossils and has been
extinct for over half a billion years, no one knows why it would have
undergone the rotation. (Perhaps one of its ancestors had changed its
posture, like the flounder, and subsequently righted itself. Evolution,
which has no foresight, may have put its head back into alignment
with its body by giving the head another quarter-twist in the same
direction, rather than by the more sensible route ofundoing the origi­
nal quarter-twist.) But it does not really matter; Kinsbourne is only
proposing that such a rotation must have taken place; he is not claim­
ing he can reconstruct why it happened. (In the case of the snail,
where the rotation is accompanied by a bending, like one of the arms
of a pretzel, scientists are more knowledgeable. As myoid biology
textbook explains, “While the head and foot remain stationary, the
visceral mass is rotated through an angle of 180°, so that the anus …
is carried upward and finally comes to lie [above] the head. . . . The
advantages of this arrangement are clear enough in an animal that lives
in a shell with only one opening.”)
In support of the theory, Kinsbourne notes that invertebrates
have their main ne1ual cables laid along their bellies and their hearts
in their backs, whereas chordates have their neural cables laid along
their backs and their hearts in their chests. This is exactly what one
would expect from a 180-degree head-to-body turn in the transition
from one group to the other, and Kinsboume could not find any
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Language Organs and Grammar Genes
311
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< I 1 reports of an animal that has only one or two out of the three reversals that his theory says must have happened together. Major changes in body architecture affect the entire design of the animal and can be very difficult to undo. We are the descendants of that twisted creature, and half a billion years later, a stroke in the left hemisphere leaves the right arm tingly. The benefits of a symmetrical body plan all have to do with sens­ ing and moving in the bilaterally indifferent environment. For body systems that do not interact directly with the environment, the sym­ metrical blueprint can be overridden. Internal organs such as the heart, liver, and stomach are good examples; they are not in contact with the layout of the external world, and they are grossly asymmetri­ cal. The same thing happens on a much smaller scale in the micro­ scopic circuitry of the brain. Think about the act of deliberately manipulating some captive object. The actions are not being keyed to the environment; the manipulator is putting the object anywhere it wants. So the organ­ ism's forelimbs, and the brain centers controlling them, do not have to be symmetrical in order to react to events appearing unpredictably on one side or the other; they can be tailored to whatever configura­ tion is most efficient to carry out the action. Manipulating an object often benefits from a division of labor between the limbs, one holding the object, the other acting on it. The result is the asymmetrical claws of lobsters, and the asymmetrical brains that control paws and hands in a variety of species. Humans are by far the most adept manipulators in the animal kingdom, and we are the species that displays the strong­ est and most consistent limb preference. Ninety percent of people in all societies and periods in history are right-handed, and most are thought to possess one or two copies of a dominant gene that imposes the right-hand (left-brain) bias. Possessors of two copies of the reces­ sive version of the gene develop without this strong right-hand bias; they turn into the rest of the right-handers and into the left-handers and ambidextrics. Processing information that is spread out over time but not space is another function where symmetry serves no purpose. Given a cer­ 312 "'*"' The Language Instinct tain amount of neural tissue necessary to perform such a function, it makes more sense to put it all in one place with short interconnec­ tions, rather than have half of it communicate with the other half over a slow, noisy, long-distance connection between the hemispheres. Thus the control of song is strongly lateralized in the left hemispheres of many birds, and the production and recognition of calls and squeaks is somewhat lateralized in monkeys, dolphins, and mice. Human language may have been concentrated in one hemi­ sphere because it, too, is coordinated in time but not environmental space: words are strung together in order but do not have to be aimed in various directions. Possibly, the hemisphere that already contained computational microcircuitry necessary for control of the fine, deliber­ ate, sequential manipulation of captive objects was the most natural place in which to put language, which also requires sequential control. In the lineage leading to humans, that happened to be the left hemi­ sphere. Many cognitive psychologists believe that a variety of mental processes requiring sequential coordination and arrangement of parts co-reside in the left hemisphere, such as recognizing and imagining multipart objects and engaging in step-by-step logical reasoning. Gaz­ zaniga, testing the two hemispheres of a split-brain patient separately, found that the newly isolated left hemisphere had the same IQ as the entire connected brain before surgery! Linguistically, most left-handers are not mirror images of the righty majority. The left hemisphere controls language in virtually all right-handers (97%), but the right hemisphere controls language in a minority of left-handers, only about 19%. The rest have language in the left hemisphere (68%) or redundantly in both. In all of these left­ ies, language is more evenly distributed between the hemispheres than it is in righties, and thus the lefties are more likely to withstand a stroke on one side of the brain without suffering from aphasia. There is some evidence that left-handers, though better at mathematical, spatial, and artistic activities, are more susceptible to language impair­ ment, dyslexia, and stuttering. Even righties with left-handed relatives (presumably, those righties possessing only one copy of the dominant 1 Language Organs and Grammar Genes "'*"' 313 I right-bias gene) appear to parse sentences in subtly different ways than pure righties. Language, of course, does not use up the entire left half of the brain. Broca observed that Tan's brain was mushy and deformed in the regions immediately above the Sylvian fissure-the huge cleavage that separates the distinctively human temporal lobe from the rest of the brain. The area in which Tan's damage began is now called Broca's area, and several other anatomical regions hugging both sides of the Sylvian fissure affect language when they are damaged. The most prominent are shown as the large gray blobs in the diagram (see page 314). In about 98% of the cases where brain damage leads to language problems, the damage is somewhere on the banks ofthe Sylvian fissure of the left hemisphere. Penfield found that most of the spots that dis­ rupted language when he stimulated them were there, too. Though the language areas appear to be separated by large gulfs, this may be an illusion. The cerebral cortex (gray matter) is a large sheet of two­ dimensional tissue that has been wadded up to fit inside the spherical skull. Just as crumpling a newspaper can appear to scramble the pic­ tures and text, a side view of a brain is a misleading picture of which regions are adjacent. Gazzaniga's coworkers have developed a tech­ nique that uses MRI pictures of brain slices to reconstruct what the person's cortex would look like if somehow it could be unwrinkled into a flat sheet. They found that all the areas that have been impli­ cated in language are adjacent in one continuous territory. This region of the cortex, the left perisylvian region, can be considered to be the language organ. Let us zoom in closer. Tan and Mr. Ford, in whom Broca's area was damaged, suffered from a syndrome of slow, labored, ungram­ matical speech called Broca's aphasia. Here is another example, from a man called Peter Hogan. In.the first passage he describes what brought him into the hospital; in the second, his former job in a paper mill: Yes Dad ah ah Monday hospital ah ... Dad and Peter Hogan, and and ah ... Wednesday ... Wednes­ 314 ~ The Language Instinct SYLVIAN /' FISSURE ...... TEMPORAL LOBE day nine o'clock and ah Thursday ... ten o'clock ah doctors . . . two . . . two ... an doctors and . . . ah ... teeth ... yah ... And a doctor an girl ... and gums, an I. Lower Falls . . . Maine . . . Paper. Four hundred tons a day! And ah ... sulphur machines, and ah ... wood ... Two weeks and eight hours. Eight hours . . . no! Twelve hours, fifteen hours . . . workin . . . workin . . . workin! Yes, and ah . . . sulphur. Sulphur and ... Ah wood. Ah ... handlin! And ah sick, four years ago. Broca's area is adjacent to the part of the motor-control strip dedicated to the jaws, lip, and tongue, and it was once thought that Broca's area is involved in the production oflanguage (though obvi­ ously not speech per se, because writing and signing are just as affected). But the area seems to be implicated in grammatical process­ ing in general. A defect in grammar will be most obvious in the out­ put, because any slip will lead to a sentence that is conspicuously defective. Comprehension, on the other hand, can often exploit the redundancy in speech to come up with sensible interpretations with little in the way of actual parsing. For example, one can understand The dog bit the man or The apple that the boy is eating is red just by Language Organs and Grammar Genes 315 knowing that dogs bite men, boys eat apples, and apples are red. Even The car pushes the truck can be guessed at because the cause is men­ tioned before the effect. For a century, Broca's aphasics fooled neurol­ ogists by using shorrcuts. Their trickery was finally unmasked when psycholinguists asked them to act out sentences that could be under­ stood only by their syntax, like The car is pushed by the truck or The girl whom the boy is pushing is tall. The patients gave the correct interpreta­ tion half the time and its opposite half the time-a mental coin flip. There are other reasons to believe that the front portion of the perisylvian correx, where Broca's area is found, is involved in gram­ matical processing. When people read a sentence, electrodes pasted over the front of their left hemispheres pick up distinctive patterns of electrical activity at the point in the sentence at which it becomes ungrammatical. Those electrodes also pick up changes during the por­ tions of a sentence in which a moved phrase must be held in memory while the reader awaits its trace, like What did you say (trace) to John? Several studies using PET and other techniques to measure blood flow have shown that this region lights up when people listen to speech in a language they know, tell stories, or understand complex sentences. Various control tasks and subtractions confirm that it is processing the structure of sentences, not just thinking about their content, that engages this general area. A recent and very carefully designed experi­ ment by Karin Stromswold and the neurologists David Caplan and Nat Alperr obtained an even more precise picture; it showed one cir­ cumscribed part of Broca's area lighting up. So is Broca's area the grammar organ? Not really. Damage to Broca's area alone usually does not produce long-lasting severe apha­ sia; the surrounding areas and underlying white matter (which con­ nects Broca's area to other brain regions) must be damaged as well. Sometimes symptoms of Broca's aphasia can be produced by a stroke or Parkinson's disease that damages the basal ganglia, complex neural centers buried inside the frontal lobes that are otherwise needed for skilled movement. The labored speech output of Broca's aphasics may be distinct from the lack of grammar in their speech, and may impli 316 + The Language Instinct cate not Broca's area but hidden parts of the cortex nearby that tend to be damaged by the same lesions. And, most surprisingly of all, some kinds of grammatical abilities seem to survive damage to Broca's area. When asked to distinguish grammatical from ungrammatical sen­ tences, some Broca's aphasics can detect even subtle violations of the rules of syntax, as in pairs like these: John was finally kissed Louise. John was finally kissed by Louise. I want you will go to the store now. I want you to go to the store now. Did the old man enjoying the view? Did the old man enjoy the view? Still, aphasics do not detect all ungrammaticalities, nor do all aphasics detect them, so the role of Broca's area in language is maddeningly unclear. Perhaps the area underlies grammatical processing by con­ verting messages in mentalese into grammatical structures and vice versa, in pan by communicating via the basal ganglia with the prefron­ tal lobes, which subserve abstract reasoning and knowledge. Broca's area is also connected by a band of fibers to a second language organ, Wernicke's area. Damage to Wernicke's area produces a very different syndrome of aphasia. Howard Gardner describes his encounter with a Mr. Gorgan: "What brings you to the hospital?" I asked the 72-year­ old retired butcher four weeks after his admission to the hos­ pital. "Boy, I'm sweating, I'm awful nervous, you know, once in a while I get caught up, I can't mention the tarripoi, a month ago, quite a little, I've done a lot well, I impose a lot, while, on the other hand, you know what I mean, I have to run around, look it over, trebbin and all that sort of stuff." I attempted several times to break in, but was unable to do so against this relentlessly steady and rapid outflow. Finally, I put up my hand, rested it on Gorgan's shoulder, and was able to gain a moment's reprieve. Language Organs and Grammar Genes + 317 "Thank you, Mr. Gorgan. I want to ask you a few-" "Oh sure, go ahead, any old think you want. If I could I would. Oh, I'm taking the word the wrong way to say, all of the barbers here whenever they stop you it's going around and around, if you know what I mean, that is tying and tying for repucer, repuceration, well, we were trying the best that we could while another time it was with the beds over there the same thing ..." Wernicke's aphasia is in some ways the complement of Broca's. Patients utter fluent streams of more-or-less grammatical phrases, but their speech makes no sense and is filled with neologisms and word substitutions. U~e many Broca's patients, Wernicke's patients have consistent difficulty naming objects; they come up with related words or distortions of the sound of the correct one: table: "chair" elbow: "knee" clip: "plick" butter: "tubber" ceiling: "leasing" ankle: "ankley, no mankle, no kankle" comb: "close, saw it, cit it, cut, the comb, the came" paper: "piece of handkerchief, pauper, hand pepper, piece of hand paper" fork: "tonsil, teller, tongue, fung" A striking symptom of Wernicke's aphasia is that the patients show few signs of comprehending the speech around them. In a third kind of aphasia, the connection between Wernicke's area and Broca's is damaged, and these patients are unable to repeat sentences. In a fourth kind, Broca's and Wernicke's and the link between them are intact but they are an island cut off from the rest of the cortex, and these patients eerily repeat what they hear without understanding it or ever speaking spontaneously. For these reasons, and because Wer­ nicke's area is adjacent to the part of the cortex that processes sound, 318 ..... The Language Instinct the area was once thought to underlie language comprehension. But that would not explain why the speech of these patients sounds so psychotic. Wernicke's area seems to have a role in looking up words and funneling them to other areas, notably Broca's, that assemble or parse them syntactically. Wernicke's aphasia, perhaps, is the product of an intact Broca's area madly churning out phrases without the intended message and intended words that Wernicke's area ordinarily supplies. But to be honest, no one really knows what either Broca's area or Wernicke's area is for. Wernicke's area, together with the two shaded areas adjacent to it in the diagram (the angular and supramarginal gyri), sit at the cross­ roads of three lobes of the brain, and hence are ideally suited to inte­ grating streams of information about visual shapes, sounds, bodily sensations (from the "somatosensory" strip), and spatial relations (from the parietal lobe). It would be a logical place to store links between the sounds of words and the appearance and geometry of what they refer to. Indeed, damage to this general vicinity often causes a syndrome that is called anomia, though a more mnemonic label might be "no-name-ia," which is literally what it means. The neuro­ psychologist Kathleen Baynes describes "HW," a business executive who suffered a stroke in this general area. He is highly intelligent, articulate, and conversationally adept but finds it virtually impossible to retrieve nouns from his mental dictionary, though he can under­ stand them. Here is how he responded when Baynes asked him to describe a picture of a boy falling from a stool as he reaches into a jar on a shelf and hands a cookie to his sister: First of all this is falling down, just about, and is gonna fall down and they're both getting something to eat ... butthe trouble is this is gonna let go and they're both gonna fall down ... I can't see well enough but I believe that either she or will have some food that's not good for you and she's to get some for her, too ... and that you get it there because they shouldn't go up there and get it unless you tell them that they could have it. And so this is falling down and fur sure there's one they're T Language Organs and Grammar Genes + 319 ~~ :ll ~ ~ j ~ i ~:. ,~~ /0 ~ II l'( I I i going to have for food and, and this didn't come out right, the, uh, the stuff that's uh, good for, it's not good for you but it, but you love, urn mum mum [smacks lips] . . . and that so they've ... see that, I can't see whether it's in there or not ... I think she's saying, I want two or three, I want one, I think, I think so, and so, so she's gonna get this one for sure it's gonna fall down there or whatever, she's gonna get that one and, and there, he's gonna get one himself or more, it all depends with this when they fall down ... and when it falls down there's no problem, all they got to do is fix it and go right back up and get some more. HW uses noun phrases perfectly but cannot retrive the nouns to put inside them: he uses pronouns, gerunds like falling down, and a few generic nouns like food and stuff, referring to particular objects with convoluted circumlocutions. Verbs tend to pose less of a problem for anomics; they are much harder for Broca's aphasics, presumably because verbs are intimately linked to syntax. There are other indications that these regions in the rear of the perisylvian are implicated in storing and retrieving words. When peo­ ple read perfectly grammatical sentences and come across a word that makes no sense, like The boys heard Joe's orange about Africa, elec­ trodes pasted near the back of the skull pick up a change in their EEG's (although, as I have mentioned, it is only a guess that the blips are coming from below the electrodes). When people put their heads in the PET scanner, this general part of the brain lights up when they hear words (and pseudo-words, like tweal) and even when they read words on a screen and have to decide whether the words rhyme-a task requiring them to imagine the word's sounds. A very gross anatomy of the language sub-organs within the perisyl­ vian might be: front of the perisylvian (including Broca's area), gram­ matical processing; rear of the perisylvian (including Wernicke's and the three-lobe junction), the sounds of words, especially nouns, and some aspects of their meaning. Can we zoom in still closer, and locate "-.r 320 + The Language Instinct Language Organs and Grammar Genes smaller areas of brain that carry out more circumscribed language tasks? The answer is no and yes. No, there are no smaller patches of brain that one can draw a line around and label as some linguistic module-at least, not today. But yes, there must be portions of cortex that carry out circumscribed tasks, because brain damage can lead to language deficits that are startlingly specific. It is an intriguing par­ adox. Here are some examples. Although impairments of what I have been calling the sixth sense, speech perception, can arise from damage to most areas of the left perisylvian (and speech perception causes sev­ eral parts of the perisylvian to light up in PET studies), there is a specific syndrome called Pure Word Deafness that is exactly what it sounds like: the patients can read and speak, and can recognize envi­ ronmental sounds like music, slamming doors, and animal cries, but cannot recognize spoken words; words are as meaningless as if they were from a foreign language. Among patients with problems in grammar, some do not display the halting articulation of Broca's aphasia but produce fluent ungrammatical speech. Some aphasics leave out verbs, inflections, and function words; others use the wrong ones. Some cannot comprehend complicated sentences involving traces (like The man who the woman kissed (trace) hugged the child) but can comprehend complex sentences involving reflexives (like The girl said that the woman washed herself). Other patients do the reverse. There are Italian patients who mangle their language's inflec­ tional suffixes (similar to the -ing, -s, and -ed ofEnglish) but are almost flawless with its derivational suffixes (similar to -able, -ness, and -er). The mental thesaurus, in particular, is sometimes torn into pieces with clean edges. Among anomic patients (those who have trouble using nouns), different patients have problems with different kinds of nouns. Some can use concrete nouns but not abstract nouns. Some can use abstract nouns but not concrete nouns. Some can use nouns for nonliving things but have trouble with nouns for living things; others can use nouns for living things but have trouble with nouns for nonliving things. Some can name animals and vegetables but not foods, body parts, clothing, vehicles, or furniture. There are patients ·41 'If f,1: ",l, f + 321 who have trouble with nouns for anything but animals, patients who cannot name body parts, patients who cannot name objects typically found indoors, patients who cannot name colors, and patients who have trouble with proper names. One patient could not name fruits or vegetables: he could name an abacus and a sphinx but not an apple or a peach. The psychologist Edgar Zurif, jesting the neurologist's habit of giving a fancy name to every syndrome, has suggested that it be called anomia for bananas, or "banananomia." Does this mean that the brain has a produce section? No one has found one, nor centers for inflections, traces, phonology, and so on. Pinning brain areas to mental functions has been frustrating. Fre­ quently one finds two patients with lesions in the same general area but with different kinds ofimpairment, or two patients with the same impairment but lesions in different areas. Sometimes a circumscribed impairment, like the inability to name animals, can be caused by mas­ sive lesions, brain-wide degeneration, or a blow to the head. And about ten percent of the time a patient with a lesion in the general vicinity ofWernicke's area can have a Broca-like aphasia, and a patient with lesions near Broca's area can have a Wernicke-like aphasia. Why has it been so hard to draw an atlas of the brain with areas for different parts of language? According to one school of thought, it is because there aren't any; the brain is a meatloaf. Except for sensa­ tion and movement, mental processes are patterns of neuronal activity that are widely distributed, hologram-style, allover the brain. But the meatloaftheory is hard to reconcile with the amazingly specific deficits of many brain-damaged patients, and it is becoming obsolete in this "decade ofthe brain." Using tools that are getting more sophisticated each month, neurobiologists are charting vast territories that once bore the unhelpful label "association cortex" in the old textbooks, and are delineating dozens of new regions with their own functions or styles of processing, like visual areas specializing in object shape, spatial layout, color, 3D stereo-vision, simple motion, and complex motion. For all we know, the brain might have regions dedicated to proc­ esses as specific as noun phrases and metrical trees; our methods for 322 ~ The Language Instinct studying the human brain are still so crude that we would be unable to find them. Perhaps the regions look like little polka dots or blobs or stripes scattered around the general language areas of the brain. They might be irregularly shaped squiggles, like gerrymandered politi­ cal districts. In different people, the regions might be pulled and stretched onto different bulges and folds of the brain. (All of these arrangements are found in brain systems we understand better, like the visual system.) If so, the enormous bomb craters that we call brain lesions, and the blurry snapshots we call PET scans, would leave their whereabouts unknown. There is already some evidence that the linguistic brain might be organized in this tortuous way. The neurosurgeon George Ojemann, following up on Penfield's methods, electrically stimulated different sites in conscious, exposed brains. He found that stimulating within a site no more than a few millimeters across could disrupt a single func­ tion, like repeating or completing a sentence, naming an object, or reading a word. But these dots were scattered over the brain (largely, but not exclusively, in the perisylvian regions) and were found in dif­ ferent places in different individuals. From the standpoint ofwhat the brain is designed to do, it would not be surprising if language subcenters are idiosyncratically tangled or scattered over the cortex. The brain is a special kind of organ, the organ of computation, and unlike an organ that moves stuff around in the physical world such as the hip or the heart, the brain does not need its functional parts to have nice cohesive shapes. As long as the connectivity of the neural microcircuitry is preserved, its parts can be put in different places and do the same thing, just as the wires con­ necting a Sl;:t of electrical components can be haphazardly stuffed into a cabinet, or the headquarters of a corporation can be located any­ where if it has good communication links to its plants and warehouses. This seems especially true of words: lesions or electrical stimulation over wide areas of the brain can cause naming difficulties. A word is a bundle of different kinds of information. Perhaps each word is like a hub that can be positioned anywhere in a large region, as long as its Language Organs and Grammar Genes + 323 spokes extend to the parts ofthe brain storing its sound, its syntax, its logic, and the appearance ofthe things it stands for. The developing brain may take advantage of the disembodied nature of computation to position language circuits with some degree of flexibility. Say a variety of brain areas have the potential to grow the precise wiring diagrams for language components. An initial bias causes the circuits to be laid down in their typical sites; the alternative sites are then suppressed. But if those first sites get damaged within a certain critical period, the circuits can grow elsewhere. Many neurolo­ gists believe that this is why the language centers are located in unex­ pected places in a significant minority of people. Birth is traumatic, and not just for the familiar psychological reasons. The birth canal squeezes the baby's head like a lemon, and newboms frequently suffer small strokes and other brain insults. Adults with anomalous language areas may be the recovered victims of these primal injUries. Now that MRI machines are common in brain research centers, visiting journal­ ists and philosophers are sometimes given pictures of their brains to take home as a souvenir. Occasionally the picture will reveal a walnut­ sized dent, which, aside from some teasing from friends who say they knew it all along, bespeaks no ill effects. There are other reasons why language functions have been so hard to pin down in the brain. Some kinds of linguistic knowledge might be stored in multiple copies, some ofhigher quality than others, in several places. Also, by the time stroke victims can be tested system­ atically, they have often recovered some oftheir facility with language, in part by compensating with general reasoning abilities. And neurol­ ogists are not like electronics technicians who can wiggle a probe into the input or output line of some component to isolate its function. They must tap the whole patient via his or her eyes and ears and mouth and hands, and there are many computational waystations between the stimulus they present and the response they observe. For example, naming an object involves recognizing it, looking up its entry in the mental dictionary, accessing its pronunciation, articulating it, and perhaps also monitoring the output for errors by 324 + Language Organs and Grammar Genes The Language Instinct 325 inhibitory synapses, and if the sum exceeds a threshold, !fIe receiving neuron becomes active itself. A network of these toy neurons, if large enough, can serVe as a computer, calculating the answer to any problem that can be specified precisely, just like the page-crawling Turing machine in Chapter 3 that could deduce that Socrates is mortal. That is because toy neurons can be wired together in a few simple ways that turn them into "logic gates," devices that can compute the logical relations "and," "or," and "not" that underlie deduction. The meaning of the logical rela­ tion "and" is that the statement "A and B" is true if A is true and if B is true. An AND gate that computes. that relation would be one that turns itself on if all of its inputs are on. If we assume that the threshold for our toy neurons is .5, then a set of incoming synapses whose weights are each less than .5 but that sum to greater than .5, say .4 and .4, will function as an AND gate, such as the one on the left here: listening to it. A naming problem could arise if any of these processes tripped up. There is some hope that we will have better localization of men­ tal processes soon, because more precise brain-imaging technologies are rapidly being developed. One example is Functional MRI, which can measure-with much more precision than PET-how hard the different parts of the brain are working during different kinds of men­ tal activity. Another is Magneto-Encephalography, which is like EEG but can pinpoint the part of the brain that an electromagnetic signal is coming from. We will never understand language organs and grammar genes by looking only for postage-stamp-sized blobs of brain. The computa­ tions underlying mental life are caused by the wiring of the intricate networks that make up the cortex, networks with millions of neurons, each neuron connected to thousands of others, operating in thou­ sandths of a second. What would we see if we could crank up the microscope and peer into the microcircuitry of the language areas? No one knows, but I would like to give you an educated guess. Ironically, this is both the aspect of the language instinct that we know the least about and the aspect that is the most important, because it is there that the actual causes of speaking and understanding lie. I will present you with a dramatization ofwhat grammatical information processing might be like from a neuron's-eye view. It is not something that you should take particularly seriously; it is simply a demonstration that the language instinct is compatible in principle with the billiard-ball causality of the physical universe, not just mysticism dressed up in a biological metaphor. Neural network modeling is based on a simplified toy neuron. This neuron can do just a few things. It can be active or inactive. When active, it sends a signal down its axon (output wire) to the other cells it is connected to; the connections are called synapses. Synapses can be excitatory or inhibitory and can have various degrees of strength. The neuron at the receiving end adds up any signals coming in from excitatory synapses, subtracts any signals coming in from + 0-.....4.5 if.~ AND ~.6.5 if.rOR -.10 0----10-­ NOT The meaning of the logical relation "or" is that a statement "A or B" is true if A is true or if B is true. Thus an OR gate must turn on if at least one of its inputs is on. To implement it, each synaptic weight must be greater than the neuron's threshold, say .6, like the middle circuit in the diagram. Finally, the meaning of the logical relation "not" is that a statement "Not A" is true if A is false, and vice versa. Thus a NOT gate should turn its output off if its input is on, and vice versa. It is implemented by an inhibitory synapse, shown on the right, whose negative weight is sufficient to turn off an output neuron that is otherwise always on. J Here is how a network of neurons might compute a moderately complex grammatical rule. The English inflection -s as in Bitt walks is a suffix that should be applied under the following conditions: when the subject is in the third person AND singular AND the action is in the present tense AND is done habitually (this is its "aspect," in lingo)­ .""Y. ~ . 326 '*' Language Organs and Grammar Genes The Language Instinct but NOT if the verb is irregular like do, have, say, or be (for example, we say Bill is, not Bill be's). A network of neural gates that computes these logical relations looks like this: Ob DICTIONARY walkO 000 hirO Od ONSET Og 000 Of goO 000 STEM be~OO FEATURES 1st 0 person ~is RIME 2nd 0 3rdo...... 3sph g-~l y present past 0 habitual aspectprogressiVe . 0 tense 'I ~--------...0 -ed 0 -ing 0 INFLECTIONS r g~ SUFFIX 0 n First, there is a bank of neurons standing for inflectional features on the lower left. The relevant ones are connected via an AND gate to a neuron that stands for the combination third person, singular num­ ber, present tense, and habitual aspect (labeled "3sph"). That neuron excites a neuron corresponding to the -s inflection, which in turn excites the neuron corresponding to the phoneme z in a bank of neu­ rons that represent the pronunciations of suffixes. If the verb is regu­ lar, this is all the computation that is needed for the suffix; the pronunciation of the stem, as specified in the mental dictionary, is simply copied over verbatim to the stem neurons by connections I have not drawn in. (That is, the form for to hit is just hit + s; the form for to wug is just wug + s.) For irregular verbs like be, this process must be blocked, or else the neural network would produce the incor­ rect be's. So the 3sph combination neuron also sends a signal to a neuron that stands for the entire irregular form is. Ifthe person whose , j ~ 327 brain we are modeling is intending to use the verb be, a neuron stand­ ing for the verb be is already active, and it, too, sends activation to the is neuron. Because the two inputs to is are connected as an AND gate, both must be on to activate is. That is, if and only if the person is thinking of be and third-person-singular-present-habitual at the same time, the is neuron is activated. The is neuron inhibits the -s inflection via a NOT gate formed by an inhibitory synapse, preventing ises or be's, but activates the vowel i and the consonant z in the bank of neurons standing for the stem. (Obviously I have omitted many neurons and many connections to the rest of the brain.) I have hand-wired this network, but the connections are specific to English and in a real brain would have to have been learned. Con­ tinuing our neural network fantasy for a while, try to imagine what this network might look like in a baby. Pretend that each of the pools ofneurons is innately there. But wherever I have drawn an arrow from a single neuron in one pool to a single neuron in another, imagine a suite of arrows, from every neuron in one pool to every neuron in another. This corresponds to the child innately "expecting" there to be, say, suffixes for persons, numbers, tenses, and aspects, as well as possible irregular words for those combinations, but not knowing exactly which combinations, suffixes, or irregulars are found in the particular language. Learning them corresponds to strengthening some of the synapses at the arrowheads (the ones I happen to have drawn in) and letting the others stay invisible. This could work as follows. Imagine that when the infant hears a word with a z in its suffix, the z neuron in the suffix pool at the right edge of the diagram gets activated, and when the infant thinks of third person, singular number, present tense, and habitual aspect (parts of his construal of the event), those four neurons at the left: edge get activated, too. If the activation spreads backwards as well as forwards, and if a synapse gets strengthened every time it is activated at the same time that its output neuron is already active, then all the synapses lining the paths between "3rd," "singular," "present," "habitual" at one end, and "z" at the other end, get strengthened. Repeat the experience enough 328 c4->
The Language Instinct
times, and the partly specified neonate network gets tuned into the
adult one I have pictured.
Let’s zoom in even closer. What primal solderer laid down the
pools of neurons and the innate potential connections among them?
This is one of the hottest topics in contemporary neuroscience, and
we are beginning to get the glimmerings ofhow embryonic brains get
wired. Not the language areas of humans, of course, but the eyeballs
of fruit flies and the thalamuses of ferrets and the visual cortexes of
cats and monkeys. Neurons destined for particular cortical areas are
born in specific areas along the walls of’the ventricles, the fluid-filled
cavities at the center of the cerebral hemispheres. They then’ creep
outward toward the skull into their final resting place in the cortex
along guy wires formed by the glial cells (the support cells that,
together with neurons, constitute the bulk of the brain). The connec­
tions between neurons in different regions of the cortex are often laid
down when the intended target area releases some chemical, and the
axons growing every which way from the source area “sniff out” that
chemical and follow the direction in which its concentration increases,
like plant roots growing toward sources of moisture and fertilizer. The
axons also sense the presence ofspecific molecules on the glial surfaces
on which they creep, and can steer themselves like Hansel and Gretel
following the trail of bread crumbs. Once the axons reach the general
vicinity of their target, more precise synaptic connections can be
formed because the growing axons and the target neurons bear certain
molecules on their surfaces that match each other like a lock and key
and adhere in place. These initial connections are often quite sloppy,
though, with neurons exuberantly sending out axons that grow
toward, and connect to, all kinds of inappropriate targets. The inap­
propriate ones die off, either because their targets fail to provide some
chemical necessary for their survival, or because the connections they
form are not used enough once the brain turns on in fetal develop­
ment.
Try to stay with me in this neuro-mythological quest: we are
beginning to approach the “grammar genes.” The molecules that
guide, connect, and preserve neurons are proteins. A protein is speci­
1
f
Language Organs and Grammar Genes
329
fied by a gene, and a gene is a sequence of bases in the DNA string
found in a chromosome. A gene is turned on by “transcription fac­
tors” and other regulatory molecules-gadgets that latch on to a
sequence of bases somewhere on a DNA moleCule and unZip a neigh­
boring stretch, allowing that gene to be transcribed into RNA, which
is then translated into protein. Generally these regulatory factors are
themselves proteins, so the process of building an organism is an intri­
cate cascade of DNA making proteins, some of which interact with
other DNA to make more proteins, and so on. Small differences in
the timing or amount of some protein can have large effects on the
organism being built.
Thus a single gene rarely specifies some identifiable pan of an
organism. Instead, it specifies the release of some protein at specific
times in deVelopment, an ingredient ofan unfathomably complex rec­
ipe, usually having some effect in molding a suite ofparts that are also
affected by many other genes. Brain wiring in particular has a complex
relationship to the genes that lay it down. A surface molecule may not
be used in a single circuit but in many circuits, each guided by a spe­
cific combination. For example, if there are three proteins, X, Y, and
Z, that can sit on a membrane, one axon might glue itself to a surface
that has X and Y and not Z, and another might glue itself to a surface
that has Yand Z but not X. Neuroscientists estimate that about thirty
thousand genes, the majority ofthe human genome, are used to build
the brain and nervous sytem.
And it all begins with a single cell, the fertilized egg. It COntains
two copies of each chromosome, one from the mother, one from the
father. Each parental chromosome was originally assembled in the
parents’ gonads by randomly splicing together pans of the chromo­
somes of the two grandparents.
We have arrived at a point at which we can define what grammar
genes would be. The grammar genes would be stretches ofDNA that
code for proteins, or trigger the transcription of proteins, in certain
times and places in the brain, that guide, attract, or glue neurons into
networks that, in combination with the synaptic tuning that takes
330
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The Language Instinct
Language Organs and Grammar Genes
…..
331
place during learning, are necessary to compute the solution to some
grammatical problem (like choosing an affix or a word).
word comprehension) was correlated with the general cognitive ability
and memory of the birth mother, but not of the adoptive mother or
father.
So do grammar genes really exist, or is the whole idea just loopy? Can
we expect the scenario in the 1990 editorial cartoon by Brian Duffy?
A pig, standing upright, asks a farmer, “What’s for dinner? Not me, I
hope.” The farmer says to his companion, “That’s the one that
received the human gene implant.”
For any grammar gene that exists in every human being, there is
currently no way to verifY its existence directly. As in many cases in
biology, genes are easiest to identitY when they correlate with some
difference between individuals, often a difference implicated in some
pathology.
We certainly know that there is something in the sperm and egg
that affects the language abilities of the child that grows out of their
union. Stuttering, dyslexia (a difficulty in reading that is often related
to a difficulty in mentally snipping syllables into their phonemes), and
Specific Language Impairment (SLI) all run in families. This does not
prove that they are genetic (recipes and wealth also run in families),
but these three syndromes probably are. In each case there is no plau­
sible environmental agent that could act on afflicted family members
while sparing the normal ones. And the syndromes are far more likely
to affect both members of a pair of identical twins, who share an envi­
ronment and all their DNA, than both members of a pair of fraternal
twins, who share an environment and only half of their DNA. For
example, identical four-year-old twins tend to mispronounce the same
words more often than fraternal twins, and if a child has Specific Lan­
guage Impairment, there is an eighty percent chance that an identical
twin will have it too, but only a thirty-five percent chance that a frater­
nal twin will have it. It would be interesting to see whether adopted
children resemble their biological family members, who share their
DNA but not their environments. I am unaware of any adoption study
that tests for SLI or dyslexia, but one study has found that a measure
of early language ability in the first year of life (a measure that com­
bines vocabulary, vocal imitation, word combinations, jabbering, and
The K family, three generations ofSLI sufferers, whose members
say things like Carot is cry in the church and can not deduce the plural
of wug, is currently one of the most dramatic demonstrations that
defects in grammatical abilities might be inherited. The attention­
grabbing hypothesis about a single dominant autosomal gene is based
on the following Mendelian reasoning. The syndrome is suspected of
being genetic because there is no plausible environmental cause that
would single out some family members and spare their agemates (in
one case, one fraternal twin was affected, the other not), and because
the syndrome has struck fifty-three percent of the family members but
strikes no more than about three percent of the population at large.
(In principle, the family could just have been unlucky; after all, they
were not randomly selected from the population but came to the
geneticists’ attention only because of the high concentration of the
syndrome. But it is unlikely.) A single gene is thought to be responsi­
ble because if several genes were responsible, each eroding language
ability by a bit, there would be several degrees of disability among the
family members, depending on how many of the damaging genes they
inherited. But the syndrome seems to be all-or-none: the school sys­
tem and family members all agree on who does and who does not
have the impairment, and in most of Gopnik’s tests the impaired
members cluster together at the low end of the scale while the normal
members cluster at the high end, with no overlap. The gene is thought
to be autosomal (not on the X chromosome) and dominant because
the syndrome struck males and females with equal frequency, and in
all cases the Spouse of an impaired parent, whether husband or wife,
was normal. If the gene were recessive and autosomal, it would be
necessary to have two impaired parents to inherit the syndrome. If it
were recessive and on the X chromosome, only males would have it;
females would be carriers. And ifit were dominant and on the X chro­
mosome, an impaired father would pass it on to all of his daughters
and none ofhis sons, because sons get their X chromosome from their
From the Academy
The acquisition of language by children
Jenny R. Saffran*, Ann Senghas†, and John C. Trueswell‡§
*Department of Psychology, University of Wisconsin, Madison, WI 53706-1696; †Department of Psychology, Barnard College of Columbia University,
New York, NY 10027-6598; and ‡Department of Psychology, University of Pennsylvania, Philadelphia, PA 19104-6196
I
magine that you are faced with the following challenge. You must
discover the internal structure of a system that contains tens of
thousands of units, all generated from a small set of materials.
These units, in turn, can be assembled into an infinite number of
combinations. Although only a subset of those combinations is
correct, the subset itself is for all practical purposes infinite.
Somehow you must converge on the structure of this system to use
it to communicate. And you are a very young child.
This system is human language. The units are words, the
materials are the small set of sounds from which they are
constructed, and the combinations are the sentences into which
they can be assembled. Given the complexity of this system, it
seems improbable that mere children could discover its underlying structure and use it to communicate. Yet most do so with
eagerness and ease, all within the first few years of life.
Below we describe three recent lines of research that examine
language learning, comprehension, and genesis by children. We
begin by asking how infants break into the system, finding the
words within the acoustic stream that serves as input to language
learning. We then consider how children acquire the ability to
rapidly combine linguistic elements to determine the relationships between these elements. Finally, we examine how children
impose grammatical structure onto their perceived input, even to
the extent of creating a new language when none is available.
These investigations provide insight into the ways in which
children extract, manipulate, and create the complex structures
that exist within natural languages.
Discovering the Units of Language
Before infants can begin to map words onto objects in the world,
they must determine which sound sequences are words. To do so,
infants must uncover at least some of the units that belong to
their native language from a largely continuous stream of sounds
in which words are seldom surrounded by pauses. Despite the
difficulty of this reverse-engineering problem, infants successfully segment words from fluent speech from ⬇7 months of age.
How do infants learn the units of their native language so rapidly?
One fruitful approach to answering this question has been to
present infants with miniature artificial languages that embody
specific aspects of natural language structure. Once an infant has
been familiarized with a sample of this language, a new sample, or
a sample from a different language, is presented to the infant.
Subtle measures of surprise (e.g., duration of looking toward the
new sounds) are then used to assess whether the infant perceives the
new sample as more of the same, or something different. In this
fashion, we can ask what the infant extracted from the artificial
language, which can lead to insights regarding the learning mechanisms underlying the earliest stages of language acquisition (1).
One important discovery using this technique has come from
the work of Saffran and colleagues (2–5), who have examined the
powerful role that statistical learning—the detection of consistent patterns of sounds—plays in infant word segmentation.
Syllables that are part of the same word tend to follow one
another predictably, whereas syllables that span word boundaries
12874 –12875 兩 PNAS 兩 November 6, 2001 兩 vol. 98 兩 no. 23
do not. In a series of experiments, they found that infants can
detect and use the statistical properties of syllable co-occurrence
to segment novel words (2). More specifically, infants do not
detect merely how frequently syllable pairs occur, but rather the
probabilities with which one syllable predicts another (3). Thus,
infants may find word boundaries by detecting syllable pairs with
low transitional probabilities. What makes this finding astonishing is that infants as young as 8 months begin to perform these
computations with as little as 2 min of exposure. By soaking up
the statistical regularities of seemingly meaningless acoustic
events, infants are able to rapidly structure linguistic input into
relevant and ultimately meaningful units.
To what extent do infants’ capacities to detect the statistics of
linguistic sounds extend to learning in nonlinguistic domains?
Interestingly, infants are also able to detect the probabilities with
which musical tones predict one another, suggesting that the
statistical learning abilities used for word segmentation may also be
used for learning materials such as music (4). In particular, infants,
but not adults, can track the statistical structure of sequences of
absolute pitches in a tone sequence learning task (5). These findings
suggest that at least some of the statistical learning mechanisms
described above are not applied solely to language learning.
The Child Parser: Packaging Words into Meaningful Units
Discovering the words of a language, and what they mean in the
world, is only the first step for the language learner. Children
must also discover how the distribution of these elements,
including grammatical endings (-s, -ed, -ing) and function words
(of, to, the) convey the further combinatorial meaning of an
utterance. That is, children must implicitly discover and use the
grammar of their language to determine who-did-what-to-whom
in each sentence. This applies even for simple sentences like
Mommy gave Daddy the milk as opposed to Daddy gave Mommy
the milk. The parsing process is therefore an essential component
of the language comprehension device, because it allows children to assemble strings of elements in such a way as to compute
crucial, and even novel, relational conceptions of the world.
Adults are quite adept at parsing sentences to determine relational meaning. In fact, studies of adult language comprehension
indicate that readers and listeners are so skilled at this process that
they typically achieve it in real time, as each word is perceived. By
measuring eye fixation and reaction time midsentence, these studies
confirm that adults rapidly package incoming words into likely
phrases using a variety of probabilistic cues gleaned from the
sentence and its referential context (e.g., refs. 6 and 7).
Recently, Trueswell and colleagues (8–10) have examined how
this rapid parsing system develops. In a series of studies, eye
movements of children age 4 and older were recorded as they heard
This paper is a summary of a session presented at the 12th annual symposium on Frontiers
of Science, held November 2– 4, 2000, at the Arnold and Mabel Beckman Center of the
National Academies of Science and Engineering in Irvine, CA.
§To
whom reprint requests should be addressed. E-mail: trueswel@psych.upenn.edu.
www.pnas.orgå…¾cgiå…¾doiå…¾10.1073å…¾pnas.231498898
Jusczyk, P. W. (1997) The Discovery of Spoken Language (MIT Press, Cambridge, MA).
Saffran, J. R., Aslin, R. N. & Newport, E. L. (1996) Science 274, 1926–1928.
Aslin, R. N., Saffran, J. R. & Newport, E. L. (1998) Psychol. Sci. 9, 321–324.
Saffran, J. R., Johnson, E. K., Aslin, R. N. & Newport, E. L. (1999) Cognition 70, 27–52.
Saffran, J. R. & Griepentrog, G. J. (2001) Dev. Psychol. 37, 74–85.
Altmann, G. & Steedman, M. (1988) Cognition 30, 191–238.
Tanenhaus, M., Spivey-Knowlton, M., Eberhard, K. & Sedivy, J. (1995) Science 268,
1632–1634.
8. Trueswell, J., Sekerina, I., Hill, N. & Logrip, M. (1999) Cognition 73, 89–134.
9. Hurewitz, F., Brown-Schmidt, S., Thorpe, K., Gleitman, L. R. & Trueswell, J. C. (2000)
J. Psycholinguistic Res. 29, 597–626.
1.
2.
3.
4.
5.
6.
7.
Saffran et al.
The Acquisition of Language by Children
These examples of language learning, processing, and creation
represent just a few of the many developments between birth and
linguistic maturity. During this period, children discover the raw
materials in the sounds (or gestures) of their language, learn how
they are assembled into longer strings, and map these combinations
onto meaning. These processes unfold simultaneously, requiring
children to integrate their capacities as they learn, to crack the code
of communication that surrounds them. Despite layers of complexity, each currently beyond the reach of modern computers, young
children readily solve the linguistic puzzles facing them, even
surpassing their input when it lacks the expected structure.
No less determined, researchers are assembling a variety of
methodologies to uncover the mechanisms underlying language
acquisition. Months before infants utter their first word, their
early language-learning mechanisms can be examined by recording subtle responses to new combinations of sounds. Once
children begin to link words together, experiments using realtime measures of language processing can reveal the ways
linguistic and nonlinguistic information are integrated during
listening. Natural experiments in which children are faced with
minimal language exposure can reveal the extent of inborn
language-learning capacities and their effect on language creation and change. As these techniques and others probing the
child’s mind are developed and their findings integrated, they will
reveal the child’s solution to the puzzle of learning a language.
10. Snedeker, J., Thorpe, K. & Trueswell, J. C. (2001) in Proceedings of the 23rd Annual
Conference of the Cognitive Science Society, eds. Moore, J. & Stenning, K. (Earlbaum,
Hillsdale, NJ), pp. 964 –969.
11. Chomsky, N. (1965) Aspects of the Theory of Syntax (MIT Press, Cambridge, MA).
12. Newport, E. L. (1990) Cognit. Sci. 14, 11–28.
13. Pinker, S. (1994) The Language Instinct (Morrow, New York).
14. Senghas, A. & Coppola, M. E. V. (2001) Psychol. Sci. 12, 323–328.
15. Supalla, T. (1982) Ph.D. thesis (University of California, San Diego).
16. Senghas, A., Coppola, M., Newport, E. L. & Supalla, T. (1997) in Proceedings of the 21st
Annual Boston University Conference on Language Development, eds. Hughes, E., Hughes, M.
& Greenhill, A. (Cascadilla, Boston), pp. 550–561.
PNAS å…© November 6, 2001 å…© vol. 98 å…© no. 23 å…© 12875
ACADEMY
Language Acquisition as Creation
Although distributional analyses enable children to break into the
words and phrases of a language, many higher linguistic functions
cannot be acquired with statistics alone. Children must discover the
rules that generate an infinite set, with only a finite sample. They
evidently possess additional language-learning abilities that enable
them to organize their language without explicit guidance (11).
These abilities diminish with age (12) and may be biologically based
(13). However, scientific efforts to isolate them experimentally
encounter a methodological complication: given that today’s languages were acquired by children in the past, language input to
children already includes products of innate biases. It is therefore
difficult to determine whether any particular linguistic element
observed in a child’s language is inborn or derived.
We can break this logical circle by examining those rare
situations in which the language environment is incomplete or
impoverished. Can children who are deprived of exposure to a
rich, complete language nevertheless build a structured native
language? The recent situation of deaf children in Nicaragua
presents such a case.
Nicaraguan Sign Language first appeared only two decades
ago among deaf children attending new schools for special
education in Managua, Nicaragua. Their language environment
provided incomplete linguistic input: they could not hear the
Spanish spoken around them, and there was no previously
developed sign language available. The children responded by
producing gestures that contained grammatical regularities not
found in their input, and in the process created a new, natural
sign language. The language continues to develop and change as
new generations of children enter school and learn to sign from
older peers. Thus, there is a measurable discrepancy between the
input to which each wave of arrivals was exposed and the
language they acquired, evident in comparisons between the first
wave of children (now adults in their 20s) and the second wave
of children (now adolescents) (14).
One such development is in their expression of semantic roles,
that is, in their use of language structure to indicate who-did-whatto-whom in an event (as in the difference in English between the girl
pushes the boy and the boy pushes the girl). The first group of children
invented signs for the things they needed to talk about (girl, boy,
push, give, fall, etc.) and immediately began developing ways to
string them together into sentences. For example, to describe
events, they would name each participant followed by its role, such
as girl push boy fall, or boy give girl receive.
The second wave of children to acquire the language added even
more structure. Within a few years, not only was the order of the
signs important, it also mattered where signs were produced. Once
the boy and girl had been mentioned, push produced to one side
would mean the girl was pushed, and to the other side would mean
the boy was pushed. The children had developed spatial devices to
indicate semantic roles, a feature typical of sign languages (e.g., ref.
15). The use of such constructions is evident today among Nicaraguan adolescents, but not adults (16). In fact, without contextual
cues, adolescent signers will give a more narrow interpretation than
that intended by adult signers, despite the fact that such signing
represents their initial input.
These findings indicate that children can apply their own
organizational biases to input that is not richly structured. Even
when cues are absent from their environment, children can turn
to inborn learning abilities to converge on a common language
as a community.
FROM THE
instructions to move objects about on a table. Children’s visual
interrogation of the scene during the speech provided a window into
the ongoing interpretation process. Of particular interest was their
reaction to ambiguous instructions that required an implicit grammatical choice, e.g., Tap the doll with the stick. Here the phrase with
the stick can be linked to the verb Tap, indicating how to do the
tapping, or it can be linked to the noun doll, indicating which doll
to tap. Adults tend to rely on the referential context when making
choices like these, picking the analysis that is most plausible given
the current scene. Which analysis did children choose? It depended
heavily on the kind of linguistic cues found in the utterance itself.
For instance, regardless of how likely the analysis was given the
scene, children would interpret with the stick as how to carry out the
action when the verb was of the sort like Tap, which tends to
mention an instrument as part of its event. In contrast, they would
interpret this same phrase as picking out a particular doll when the
verb was of the sort that tends not to mention an instrument, e.g.,
Feel (8, 10).
Thus, like the Saffran et al. infants who used probabilistic cues
to package syllables into likely words, older children package
words into likely phrases using similar distributional evidence
regarding these larger elements. Further experience is apparently necessary to detect the contingencies of when phrases are
likely in given referential settings. Indeed, Trueswell et al. found
that by age 8, children begin parsing ambiguous phrases in a
context-contingent manner (8).
,
OTHER BOOKS BY STEVEN PINKER
Words and Rules: The Ingredients of Language
Language Learnability
and Language Development
Learnability and Cognition:
The Acquisition of Argument Structure
steven pinker
The
Language Instinct
HOW THE MIND CREATES LANGUAGE
PERENNIAL
•
CLASSICS
The Big Bang
, ·
ll
+
The Btq Bang
‘r~ .
The elephant)s trunk is six feet long and one foot thick and contains sixty
thousand muscles. Elephants can use their trunks to uproot trees, stack
~( timber, or carefully place huge logs in position when recruited to build
bridges. An elephant can curl its trunk around a pencil and draw charac~l..
ter on letter-size paper. With the two muscular extensions at the tip, it

can remove a thorn, pick up a pin or a dime, uncork a bottle, slide the
.~ bolt off a cage door and hide it on a ledge, or grip a cup so firmly,
without breaking it, that only another elephant can pull it away. The tip
is sensitive enough for a blindfolded elephant to ascertain the shape and
texture of objects. In the wild, elephants use their trunks to pull up
clumps of grass and tap them against their knees to knock off the dirt,
to shake coconuts out of palm trees, and to powder their bodies with
dust. They use their trunks to probe the ground as they walk, avoiding
pit traps, and to dig wells and siphon water from them. Elephants can
walk underwater on the beds of deep rivers or swim like submarines for
miles, using their trunks as snorkels. They communicate through their
trunks by trumpeting, humming, roaring, piping, purring, rumbling,
and making a crumpling-metal sound by rapping the trunk against the
ground. The trunk is lined with chemoreceptors that allow the elephant
to smell a phython hidden in the grass or food a mile away.
*’
+
341
Elephants are the only living animals that possess this extraordinary organ. Their closest living terrestrial relative is the hyrax, a mamal that you would probably not be able to tell from a large guinea
~g Until now you have probably not given the uniqueness of the
~:e~hant’s trunk a moment’s thought. Certainly no biologist has made
a fuss about it. But now imagine what might happen if some biologists
were elephants. Obsessed with the unique place of the trunk in nature,
they might ask how it could have evolved, given that no other organism has a trunk or anything like it. One s~hool might try to think up
ways to narrow the gap. They would first point out that the elephant
and the hyrax share about 90% of their DNA and thus could not be
all that different. They might say that the trunk must not be as complex as everyone thought; perhaps the number of muscles had been
miscounted. They might further note that the hyrax really does have
a trunk, but somehow it has been overlooked; after all, the hyrax does
have nostrils. Though their attempts to train hyraxes to pick up
objects with their nostrils have failed, some might trumpet their success at training the hyraxes to push toothpicks around with their
tongues, noting that stacking tree trunks or drawing on blackboards
differ from it only in degree. The opposite school, maintaining the
uniqueness of the trunk, might insist that it appeared all at once in the
offspring of a particular trunkless elephant ancestor, the product of a
single dramatic mutation. Or they might say that the trunk somehow
arose as an automatic by-product of the elephant’s having evolved a
large head. They might add another paradox for trunk evolution: the
trunk is absurdly more intricate and well coordinated than any ancestral elephant would have needed.
These arguments might strike us as peculiar, but every one of
them has been made by scientists of a different species about a com~lex organ that that species alone possesses, language. As we shall see
tn this chapter, Chomsky and some of his fiercest opponents agree
?n one thing: that a uniquely human language instinct seems to be
Incompatible with the modem Darwinian theory of evolution, in
Which complex biological systems arise by the gradual accumulation
over generations of random genetic mutations that enhance reproduc-
342
The Language Instinct
rive success. Either there is no language instinct, or it must ha
Ve
evolved by other means. Since I have been trying to convince you that
there is a language •in~tinct but would certainly forgive you if You
would rather believe Darwin than believe me, I would also like to
convince you that you need not make that choice. Though we know
few details about how the language instinct evolved, there is no reason
to doubt that the principal explanation is the same as for any other
complex instinct or organ, Darwin’s theory of natural selection.
Language is obviously as different from other animals’ communicatlon systems as the elephant’s trunk is different from other animals’
nostrils. Nonhuman communication systems are based on one of
three designs: a finite repertory of calls (one for warnings of predators,
one for claims to territory, and so on), a continuous analog signal that
registers the magnitude of some state (the livelier the dance of the
bee, the richer the food source that it is tellihg its hivemates about),
or a series of random variations on a theme (a birdsong repeated with
a new twist each time: Charlie Parker with feathers). As we have seen,
human language has a very different design. The discrete combinatorial system called “grammar” makes human language infinite (there is
no limit to the number of complex words or sentence in a language),
digital (this infinity is achieved by rearranging discrete elements in
particular orders and combinations, not by varying some signal along
a continuum like the mercury in a thermometer), and compositional
(each of the infinite combinations has a different meaning predictable
from the meanings of its parts and the rules and principles arranging
them).
Even the seat of human language in the brain is special. The vocal
calls of primates are controlled not by their cerebral cortex but by
phylogenetically older neural structures in the brain stem ancl limbic
systems, structures that are heavily involved in emotion. Human
vocalizations other than language, like sobbing, laughing, moaning,
and shouting in pain, are also controlled §!lhcorrjca.!!y. Subcortical
structures even control the swearing that follows the arrival of a ham·
~ mer on a thumb, that emerges as an involuntary tic in Tourette’s syn-
CE>
.
The Big Bang
343
dr0 me, and that can survive as Broca’s aphasics’ only speech. Genuine
Janguage, as we saw in the preceding chapter, is seated in the cerebral
cortex, primarily the left perisylvian region.
Some psychologists believe that changes in the vocal organs and
in the neural circuitry that produces and perceives speech sounds are
the only aspects of language that evolved in our species. On this view,
there are a few general learning abilities found throughout the animal
kingdom, and they work most efficiently_in humans. At some point in
history language was invented and refined, and we have been learning
it ever since. The idea that species-specific behavior is caused by anatomy and general intelligence is captured in the Gary Larson Far Side
cartoon in which two bears hide behind a tree near a human couple
relaxing on a blanket. One says: “C’mon! Look at these fangs! …
Look at these claws! … You think we’re supposed to eat just honey
and berries?”
According to this view, chimpanzees are the second-best learners
in the animal kingdom, so they should be able to acquire a language
too, albeit a simpler one. All it takes is a teacher. In the 1930s and
1940s two psychologist couples adopted baby chimpanzees. The
chimps became part of the family and learned to dress, use the toilet,
brush their teeth, and wash the dishes. One of them, Gua, was raised
alongside a boy of the same age but never spoke a word. The other,
Viki, was given arduous training in speech, mainly by the foster parents’ moulding the puzzled chimp’s lips and tongue into the right
shapes. With a lot of practice, and often with the help of her own
hands, Viki learned to make three utterances that charitable listeners
could hear as papa, mama, and cup, though she often confused them
When she got excited. She could respond to some stereotyped formulas, like Kiss me and Bring me the dog, but stared blankly when asked
to act out a novel combination like Kiss the dog.
(1 ~ # .
. But Gua and Viki were at a disadvantage: they were forced to use bd ~I’
the1r Y.Q.cal apparatus, ‘Yhich was not designed for speech and which ‘It~~
they could not voluntarily control. Beginning in the late 1960s, sev- 07′ ~
era1 famous projects claimed to have taught language to baby chim- ~ ~~
Panzees with the help of more user-friendly media. (Baby chimps are
~ “t….
—
“(
344
+
The Big Bang
The Language Instinct
used because the adults are not the hairy clowns in overalls you see on
television, but strong, vic!ous wild animals who have bitten fingers off
several well-known psychologists.) Sarah learned to string magnetized
lv.
plastic shapes on a board. Lana and Kanzi learned to press buttons
qJ
with symbols on a large computer console or point to them on a por10~ table tablet. Washoe and Koko (a gorilla) were said to have acquired
American Sign Language. According to their trainers, these apes
learned hundreds of words, strung them together in meaningful sentence, and coined new phrases, like water bird for a swan and cookie
rock for a stale Danish. “Language is no longer the exclusive domain
of man,” said Koko’s trainer, Francine (Penny) Patterson.
These claims quickly captured the public’s imagination and were
played up in popular science books and magazines and television programs like National Geographic, Nova, Sixty Minutes, and 20/20. Not
only did the projects seem to consummate our age -old yearning to
talk to the animals, but the photo opportunities of attractive women
communing with apes, evocative of the beauty-and-the-beast archetype, were not lost on the popular media. Some of the projects were
covered by People, Life, and Penthouse magazines, and they were fictionalized in a bad movie starring Holly Hunter called Animal Behavior and in a famous Pepsi commercial.
Many scientists have also been captivated, seeing the projects as
a healthy deflation of our species’ arrogant chauvinism. I have seen
popular-science columns that list the acquisition oflanguage by chimpanzees as one of the major scientific discoveries of the century. In a
recent, widely excerpted book, Carl Sagan and Ann Druyan have used
the ape language experiments as part of a call for us to reassess our
place in nature:
A sharp distinction between human beings and “animals” is
essential if we are to bend them to our will, make them work
for us, wear them, eat them- without any disquieting tinges of
guilt or regret. With untroubled consciences, we can render
whole species extinct-as we do today to the tune of 100
speces a day. Their loss is oflittle import: Those beings, we tell
+
345
ourselves, are not like us. An unbridgeable gap has thus a practical role to play beyond the mere stroking of human egos. Isn’t
there much to be proud of in the lives of monkeys and apes?
Shouldn’t we be glad to acknowledge a connection with
Leakey, Imo, or Kanzi? Remember those macaques who would
rather go hungry then profit from harming their fellows; might
we have a more optimistic view of the human future if we were
sure our ethics were up to their standards? And, viewed from
this perspective, how shall we judge our treatment of monkeys
and apes?
This well-meaning but misguided reasoning could only have come
from writers who are not biologists. Is it really “humility” for us to
save species from extinction because we think they are like us? Or
because they seem like a bunch of nice guys? What about all the
creepy, nasty, selfish animals who do not remind us of ourselves, or
our image of what we would like to be- can we go ahead and wipe
them out? And Sagan and Druyan are no friends of the apes if they
think the reason we should treat the apes fairly is that they can be
taught human language. Like many other writers, Sagan and Druyan
are far too credulous about the claims of the chimpanzee trainers.
People who spend a lot of time with animals are prone to developing indulgent attitudes about their powers of communication. My
great -aunt-Bella insisted in all sincerity that her Siamese cat Rusty
understood English. __Many of the claims of the ape trainers were n~t
much more scientific. Most of the trainers were schooled in the behaviorist tradition of B. F . Skinner and are ignorant of the study of language; they latched on to the most tenuous resemblance between
chimp and child and proclaimed that their abilities are fundamentally
the same . The more enthusiastic trainers went over the heads of scientists and made their engaging case directly to the public on the
Tonight Show and National Geographic. Patterson in particular has
found ways to excuse Koko’s performance on the grounds that the
gorilla is fond of puns, jokes, metaphors, and mischievous lies. Generally the stronger the claims about the animal’s abilities, the skimpier
346
The Big Bang
The Language Instinct
the data made available to the scientific community for evaluation.
Most of the trainers have refused all request to share their raw data,
and Washoe’s trainerS, lkatrice and Alan Gardner, threatened to sue
another researcher because he used frames of one of their films (the
.1J· only raw data available to him) in a critical scientific article. That
.t., ‘.~ researcher, Herbert Terrance, together with the psychologists Lara
‘~ Ann Petitto, Richard Sanders, and Tom Bever, had tried to teach ASL
..r;~ ‘P to one ofWashoe’s relatives, whom they named Nim ChimpsQ They
carefully tabulated and analyzed his signs, and Petitto, with the psychologist Mark Seidenberg, also scrutinized the videotapes and what
published data there were on the other signing apes, whose abilities
were similar to Nim’s. More recently, Joel Wallman has written a history of the topic called Aping Language. The moral of their investigations is: Don’t believe everything you hear on the Tonight Show.
To begin with, the apes did not “learn American Sign Language.” This preposterous claim is based on the myth that ASL is a
crude system of pantomimes and gestures rather than a full language
with complex phonology, morphology, and syntax. In fact the apes
had not learned any true ASL signs. The one deaf native signer on the
Washoe team later made these candid remarks:
Every time the chimp made a sign, we were supposed to write
it down in the log .. . . They were always complaining because
my log didn’t show enough signs. All the hearing people
turned in logs with long lists of signs. They always saw more
signs than I did . . . . I watched really carefully. The chimp’s
hands were moving constantly. Maybe I missed something, but
I don’t think so. I just wasn’t seeing any signs. The hearing
people were logging every movement the chimp made as a
sign. Every time the chimp put his finger in his mouth, they’d
say “Oh, he’s making the sign for drink,” and they’d give him
some milk . … When the chimp scratched itself, they’d record
it as the sign for scratch . … When [the chimps] want something, they reach. Sometimes [the trainers would] say, “Oh,
amazing, look at that, it’s exactly like the ASL sign for give!”
It wasn’t.
347
To arrive at their vocabulary counts in the hundreds, the investigators
would also “translate” the chimps’ pointing as a sign for you, their
hugging as a sign for hug, their picking, tickling, and kissing as signs
for pick, tickle, and kiss. Often the same movement would be credited
to the chimps as different “words,” depending on what the observers
thought the appropriate word would be in the context. In the experiments in which the chimps interacted with a computer console, the
key that the chimp had to press to i~tialize the computer was translated as the word please. Petitto estimates that with more standard
criteria the true vocabulary count would be closer to 25 than 125.
Actually, what the chi~2.~.r.oeally: doing was mo!!i,nteresting
than w~they-;;.e claimed to be doing. Jane Goodall, vi~·
project, remarked to Terr~ and Petitt~ that every one of Nim’s socalled signs was familiar to her from her observations of chimps in the
wild. ~ chimns were relying heavily~ on the gestures in their natural
:r
~
…… – – – – repertoire, rather than learning true arbitrary ASL signs with their
combinatorial phonological structure of hand shapes, motions, locations, and orientations. Such backsliding is common when humans
train animals. Two enterprising students of B. F. Skinner, Keller and
Marian Breland, took his principles for shaping the behavior of rats
and pigeons with schedules of reward and turned them into a lucrative
career of training circus animals. They recounted their experiences in
a famous article called “The Misbehavior of Organisms,” a play on
Skinne(s book The Behavior of Organisms. In some of their acts the
animals were trained to insert poker chips in little juke boxes and vending machines for a food reward. Though the training schedules were
the same for the various animals, their species-specific instincts bled
through. The chickens spontaneously pecked at the chips, the pigs
tossed and rooted them with their snouts, and the raccoons rubbed
and washed them.
The chimp’s abilities at anything one would want to call grammar were next to nil. Signs were not coordinated into the well-defined
motion contours of ASL and were not inflected for aspect, agreement,
and so on-a striking omission, since inflection is the primary means
in ASL of conveying who did what to whom and many other kinds of
–
348
‘”*-‘
The Language Instinct
information. The trainers frequently claim that the chimps have syntax, because pairs of signs are sometimes placed in one order more
often than chance woUld,. predict, and because the brighter chimps can
act out sequences like Would you please carry the cooler to Penny. But
remember from the Loebner Prize competition (for the most convincing computer simulation of a conversational partner) how easy it is to
fool people into thinking that their interlocutors have humanlike talents: To understand the request, the chimp could ignore the symbols
would, you, please, carry, the, and to; all the chimp had to notice was
the order of the two nouns (and in most of the tests, not even that,
because it is more natural to carry a cooler to a person than a person
to a cooler). True, some of the chimps can carry out these commands
more reliably than a two-year-old child, but this says more about temperament than about grammar: the chimps are highly trained animal
acts, and a two-year-old is a two-year-old.
As far as spontaneous output is concerned, there is no comparison. Over several years of intensive training, the average length of
the chimps’ “sentences” remains constant. With not…
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