The Making of the Mind: The Neuroscience of Human Nature (13 page)

Exactly why children are able to acquire implicitly the syntax of their native language with such seeming ease is a controversial issue in cognitive science.
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The nativist view is that the human genome has encoded neural systems that are dedicated to the acquisition of language. On this view, a universal grammar, providing expectations about the way all languages are structured, and a language acquisition device are innate components of the human brain. Other theorists question the need for these entities and argue instead that general learning capabilities are sufficient to acquire the syntax of one's native language. Despite decades of research by linguists and psychologists, the issue remains unresolved.

The machinery of language is bolted together by the social interactions of human beings. What we say and how we say it is ultimately shaped by
those who listen to, comprehend, interpret, and respond to our utterances. For example, if it is too hot in a room you might say to others sitting near the window: “Open the window!” But barking out a command is rude among social equals. So you might instead ask a polite question: “Could you please open the window?” The listeners would not take this as a literal question about their physical or cognitive capacities. Rather, they would infer that you would like the window opened. You might even make a simple declaration: “It sure is hot in here.” Although the inference required is a bit more complex, listeners would likely understand that you are really doing more than expressing how you feel at the moment.

Pragmatics
is a term used to describe how language use is shaped by its social context.
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Although we sometimes talk aloud to ourselves or use covert language to think in silence, spoken language generally takes place in a conversation with others who understand and can produce the language. Language is in large measure employed in dialogue rather than monologue. Speakers and listeners take turns and participate in a ritual of give and take, sharing ideas back and forth. Conversing together follows a rhythm of social interaction that bears much resemblance to other joint activities, such as dancing or playing tennis.

Violations of the pragmatic rules of language are as glaringly apparent to us as hearing an ungrammatical string of words that does not fit the rules of syntax. For example, if one speaker in a small group hogs the conversation and refuses to allow others a chance to speak, the failure to take turns is obvious and irritating. Participants agree to say things that are appropriate to the conversation and to end the conversation at a mutually agreeable point. For example, a partner who appears incapable of ending a conversation or who brings up touchy subjects at a party becomes someone to avoid. Speaking audibly in a shared language is required. Imagine a small group of conversationalists in which two of the participants keep whispering to each other or speak in a language only the two of them can comprehend—the couple's secrecy is not amusing to the others. One of the trickiest rules of cooperation is to be informative and truthful. An evasive speaker easily annoys listeners and is not always successful in concealing the truth. But at the same time insulting others with the truth is not socially adept either. Compliments, even when they are little white lies, can be socially useful.

The pragmatic dimension shows us that language is of one piece with the social cognition of joint activities of all kinds.
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Some joint activities are highly verbal in nature, such as dialog, whereas others are less so, such as playing cards or making love. In all joint activities, the two or more individuals meld their attention into a shared mental space. Although dialog is more verbal than other joint activities, the fact that people share common ground as the basis for their conversation means that utterances can often be remarkably telegraphic in nature. One of the rules of conversation is to say as much as is necessary but no more—there is no need to state things explicitly when they are part of the common ground. For example, imagine a boy and a girl watching a television program together. The boy, holding the remote control, asks: “Boring?” The girl responds: “Switch.” Immediately, the boy starts to channel surf. Because the current program was the focus of joint attention, there was no need for the boy to say, “Do you think this program is boring?” And the girl did not need to even respond to his single word question by saying, “Yes, I think it is boring, so please change the channel.” In the joint activity of dialog, meanings can be grasped with a minimum of words and no need for even simple syntax. Indeed, had the girl simply rolled her eyes, the boy would probably have understood and switched channels.

THE ROOTS OF LANGUAGE

Humans are not alone in thinking and communicating, as Donald R. Griffin documented throughout his 1984 book titled
Animal Thinking
. For example, a honeybee can direct other members of the hive to distant sources of nectar by waggling its body as a signal. The precise nature of the bee's waggle dance communicates the direction and distance from the hive of a source discovered by the dancing bee. Other kinds of animal communication systems include the antennae and head gestures of weaver ants, the complex sonar signaling of dolphins and whales, and the alarm calls of monkeys. By studying the communication systems of primates, it may be possible to identify the roots of language.

For example, vervet monkeys from Eastern Africa make five different kinds of calls—each warns others in their group to the impending danger posed by one
of five different predators.
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Similarly, Diana monkeys, a type of West African monkey, make distinct calls to signal their distress about different predators. For example, one call is used to warn others of an eagle circling overhead, whereas another different sound is produced when the leopard is approaching on the ground. Yet it is unclear what exactly the monkeys are experiencing when they produce and perceive these alarm signals. Are they just responding to the sounds of the calls or do these calls trigger a mental representation of the eagle versus a leopard? Are they really referring to a specific referent or do they simply signal the importance of orienting to the environment to detect a threat of some unspecified kind? Just because a different signal is used for different predators does not necessarily mean that the producer is mentally representing a specific class of predator or that the listener does so on hearing it. In other words, do these calls truly point to a specific referent?

In a field experiment, researchers played a recording of the sound of an eagle call to wild Diana monkeys. As they would with a real eagle, the group immediately began emitting a high rate of Diana eagle alarm calls designed to warn of the danger overhead. Within five minutes the rate of calling decreased to zero, because they had already warned each other of the presence of the eagle. In fact, if another eagle call is then immediately played, the monkeys do not sound the alarm at all. So, what would happen if a Diana eagle alarm were played first, instead of the call of an actual eagle? Would the monkey understand the meaning of this and promptly join in to warn others? Would they after five minutes then completely ignore a real eagle call? The answer is yes to both questions.
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The results seem to imply that the Diana eagle alarm call actually refers to a real eagle. In other words, the primate brain shows the rudimentary capacity to use a sign with a specific meaning.

It would be going too far, however, to equate a monkey's predator call with a word. The call is used when the monkey perceives an actual eagle or leopard in the environment. It is used to signal a threat about the here and now. The call is not typically used when the threats are not physically present. It could be that the call is acting as a conditioned stimulus to an unconditioned hide or flee response. By pairing the call with the specific predator present, the monkeys would learn to hide or flee in response to the call alone. If this is so, then it may be that “monkey alarm calls do not refer symbolically
to snakes, eagles or leopards, but rather elicit differentially conditioned flee responses associated with the presences of these predators.”
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Words, by contrast, allow symbolic thinking about the concept of an eagle or a leopard anytime, anywhere. The word can be disconnected from an immediate physical referent and employed in thinking about the concept in general. The word is acting as a symbol detached from the referent object in the real world; that is, it refers to a concept in the mind. It is this symbolic power of words that allows us to invent words for abstract concepts that are purely imaginary (e.g., a unicorn or the square root of -1).

There is an interesting exception in that primates employ “deliberate uses of alarm calls in the absence of any predator, designed to distract other monkeys from aggressive intentions or to remove potential competitors for some item of food.”
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The monkeys appear to have learned that an alarm call can be used to deceive others precisely because the species as a whole interprets it as a signal of imminent physical danger. Again, they could have learned how to deceive using the call as a conditioned stimulus. By contrast, we can listen to a story about a leopard without panicking, fearing an imminent attack, and fleeing. The human word
leopard
is clearly acting as a symbol for a concept.

What, then, can be said about the language capabilities of chimpanzees? Does the 2 percent or so difference in our genomes preclude language in nonhumans? The focus of research has not been on the communication abilities of wild chimpanzees, but rather on attempts to teach chimpanzees language in laboratory environments. This line of research has a long history, with early efforts dating to the 1930s. Winthrop and Luella Kellogg attempted to teach a chimpanzee to speak by raising it with their own son and treating the chimpanzee as a human being. The chimpanzee, named Gua, was not explicitly trained, but rather was expected to learn by observation right along with their son, Donald. As Roger Fouts recounted the history in his book
Next of Kin
: “Unfortunately for science the Kelloggs abruptly terminated the study because, rumor has it, Mrs. Kellogg became distressed when Donald began acquiring more chimpanzee sounds than Gua was acquiring animal sounds.”
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One reason for the Kelloggs’ failed effort likely was the superior skill at imitation shown by human beings compared with chimpanzees. However, an inherent limitation in the vocal track of the chimpanzee to produce the phonemes
of human speech was fatal to the project. Unlike parrots, which can mimic human speech sounds to a degree, apes cannot match the full range and felicity of human speech production.

The difficulty lies in the location of the chimpanzee's larynx.
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The human larynx, where the vocal cords are located, begins at birth in a high position in the vocal tract, comparable to the position found in the chimpanzee. However, beginning at about three months of age in a human being, the larynx migrates lower in the neck into the pharynx, assuming its adult position around fifteen years of age. For all mammals except human beings, the laryngeal tract that connects the nasal passages and mouth to the lungs is clearly separate from the pharyngeal tract that connects the mouth to the esophagus on its way to the stomach. Mammals can eat and breathe at the same time without worries of chocking on food or drink. In the design of human beings, this obvious advantage for the survival of the species was given up in order to position the larynx low in the throat. Why? Because the precarious position of our larynx permits the articulation of an astonishing range of sounds that constitute the phonemes of language. Without it we could not articulate the three vowels
i
,
u
, and
a
or the consonants
k
and
g
. The larynx starts at birth in a high position that permits a new born to nurse and breathe simultaneously without danger of choking to death. The larynx then descends, and by the age of three months the infant cannot eat and breathe at the same time. But the infants capacity to babble all of the possible phonemes of all possible human languages begins to emerges along with its descent. Speech is such a powerful adaptation that
Homo sapiens
risk asphyxiation to attain it.

The low position of the larynx is not the only biological adaptation for speech. The chimpanzee lacks the extraordinary vocal control of human beings. In other words, the brain's motor control of the lips, tongue, jaw, and other components of sound articulation differ markedly in the two species. A critical gene for speech motor control, called FOXP2, has in fact been identified. By studying the genetic basis of a disorder of the face and mouth muscles, scientists were able to identify a mutation of the FOXP2 underlying the disorder.
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In a particular family, across three generations, half of the members suffered from the disorder that severely impaired their speech because the oral movements required for articulating the phonemes of speech could not be controlled.
The disease starts early in childhood and impairs not only the normal progression of learning and using oral language but also the language and grammar skills that come later, including writing. The inheritance pattern revealed a single mutated gene that disrupted the development of the basal ganglia in the telencephalon of the brain that are known to be crucial for motor control.

The FOXP2 gene is also found in other primates. However, it is a slightly different variant in humans compared with nonhuman primates. Without this variant intact in human beings, there is severe impairment of the motor output of speech. Thus, lacking the right larynx and control of sound articulation, the chimpanzee physically cannot imitate human speech—the precise motor control is lacking. This difference between chimpanzees and human beings suggests that “some human-specific feature of FOXP2…affect a person's ability to control orofacial movements and thus to develop proficient spoken language.”
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