The First Word: The Search for the Origins of Language (23 page)

Schwartz, Howe, and Purves analyzed a vast selection of speech sounds from a variety of languages to determine the underlying patterns common to all utterances. In order to focus only on the raw sound, they discarded all theories about speech and meaning and sliced sentences into random bites. Using a database of over a hundred thousand brief segments of speech, they noted which frequency had the greatest emphasis in each sound. The resulting set of frequencies, they discovered, corresponded closely to the chromatic scale. In short, the building blocks of music are to be found in speech.

“Music, like the visual arts, is rooted in our experience of the natural world,” said Schwartz. “It emulates our sound environment in the way that visual arts emulate the visual environment.” In music we hear the echo of our basic sound-making instrument—the vocal tract. This explanation for human music is simpler still than Pythagoras’s mathematical equations: we like the sounds that are familiar to us—specifically, we like sounds that remind us of us.

This brings up some chicken-or-egg evolutionary questions. It may be that music imitates speech directly, the researchers say, in which case it would seem that language evolved first. It’s also conceivable that music came first and language is in effect an imitation of song—that in everyday speech we hit the musical notes we especially like. Alternately, it may be that music imitates the general products of the human sound-making system, which just happen to be mostly speech. “We can’t know this,” says Schwartz. “What we do know is that they both come from the same system, and it is this that shapes our preferences.”

Schwartz’s study also casts light on the long-running question of whether animals understand or appreciate music. Despite the apparent abundance of “music” in the natural world—birdsongs, whale songs, wolf howls, synchronized chimpanzee hooting—previous studies have found that many laboratory animals don’t show a great affinity for the human variety of music making. Indeed, Marc Hauser and Josh McDermott of Harvard argued in a special music issue of
Nature Neuroscience
that animals don’t create or perceive music the way we do.
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The fact that laboratory animals can show recognition of human tunes is evidence, they say, of shared general features of the auditory system, but not of any specific musical ability.

But what’s been played to the animals, Schwartz noted, is human music. If animals have evolved preferences for sound as we have—based on the soundscape in which they live—then their “music” would be fundamentally different from ours. In the same way our scales derive from human utterances, a cat’s idea of a good tune would derive from yowls and meows. To demonstrate that animals don’t appreciate sounds the way we do, we’d need evidence that they don’t respond to “music” constructed from their own sound environment.

Of course, there are many examples of animal music. Fitch (who is also an avid amateur musician, composer, and singer) argues that it is worthwhile to examine these in comparison to human music and language. Fitch examined not just animal song, like birdsong and whale song—which must be learned as we learn to sing and talk—but also examples of animal instrumentation. The best examples of instrument use in nonhuman animals are found in our very close relatives. For dominance displays and in play, chimpanzees drum on trees and other resonant objects, while gorillas drum on their own chests (and occasionally other objects). Sue Savage-Rumbaugh’s bonobos have also demonstrated an appreciation of percussion and keyboard playing (recall that they also use keyboardlike machines for linguistic communication). Instrumental music is rare in vertebrates, except for African apes, which includes us, leading Fitch to suggest that the drumming of chimpanzees and gorillas may be evolutionary homologs to human instrumental music.

Fitch has further explored the antecedents of human instrumentation via the divisive issue of Neanderthal flutes. A number of researchers have examined a fossilized cave-bear bone with two holes (and possibly another three damaged holes), attributed to Neanderthals.
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It has been argued that the object, which is radiocarbon-dated to approximately 43,000 years ago, is a flute. Although the provenance and nature of this bone are still regarded as controversial, Fitch points out that if it was a flute, it dates the origin of human instrumental music to at least the common ancestor of Neanderthals and humans,
Homo heidelbergensis
(see chapter 12), who lived more than 500,000 years ago.

No matter how the connection between language and music is parsed, what is apparent is that our sense of music, even our love for it, is as deeply rooted in our biology as language is. The upshot, said the University of Toronto’s Sandra Trehub, who also published a paper in the music issue of
Nature Neuroscience,
is that music may be “more like a necessity than the pleasure cocktail envisioned by Pinker.”

This is most obvious with babies, said Trehub, for whom music and speech are on a continuum. Mothers use musical speech, called motherese, to “regulate infants’ emotional states,” she explained.
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Regardless of what language they speak, the voice all mothers use with babies is something between speech and song. This kind of communication “puts the baby in a trance-like state, which may proceed to sleep or extended periods of rapture.” This means, explained Trehub, that music may be even more of a necessity than we realize.
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O
n July 28, 2005, Lacy Nissley was scheduled for neurosurgery at Johns Hopkins Hospital in Baltimore. Before she was born, the neurons in Lacy’s right hemisphere migrated to the wrong place in her brain. The hemisphere became enlarged and started to cause seizures that were only poorly controlled by medication. As time went on, Lacy’s seizures got worse. Nothing could be done to make her right hemisphere work well, and while it was attached to the rest of her brain, it corrupted the way the left hemisphere worked. The only chance Lacy had to live a normal life was for her to undergo a hemispherectomy. In this radical operation, Lacy’s neurosurgeon would remove her right hemisphere, essentially taking out half of her brain.

Four hours into the operation, Lacy’s neurosurgeon, Dr. George Jallo, his resident Dr. Violette Renard, and the OR nurse Sean Stelfox stood in a small, still crescent around Lacy’s head. Earlier, Jallo had removed the frontal lobe. He then used micro-scissors to cut around the parietal lobe, and now he and Renard were slowly working their way around each side, making tiny little pinches into the cut with electric cauterizing forceps. Occasionally, Jallo used a flat metal spatula to lift the lobe up and back so he could push the bipolar forceps farther in. As the cut became deeper and wider, the tissue on either side browned and blackened, and the lobe, which was initially stationary, started to move back and forth as more of it was detached from the rest of the brain.

Deep at the bottom of the parietal wedge lay the white matter of Lacy’s brain. Everything else was colored or discolored, but the long cables that connect neurons to one another gleamed toothpaste white. They came apart like string cheese. Stelfox bent toward Jallo clutching a small plastic bowl with both hands. Using normal forceps, Jallo picked out the lobe—it was the size of an infant’s fist—and dropped it into the container. Stelfox held it aloft. “The parietal lobe.”

Four hours later, the right hemisphere was gone.
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From the top of Lacy’s head, her cranium looked like a wide, uneven bowl, revealing the white-pink base of the skull from the inside and the larger, deeper cavity that had held the frontal and parietal lobes. In the middle was a shallow mound where Jallo left a layer of axons to protect the ventricle. The white matter was now gray-black. Jallo and Renard lightly touched their forceps to it, and the cauterizers fizzed, and occasionally popped and spluttered, sealing the brain against micro-hemorrhages. Just below the mound were the basal ganglia, small dark squiggles in the emptiness. Over and over Stelfox poured in saline, and Jallo and Renard drew it out again.

Jallo filled the right side of Lacy’s head with saline, and over the next few days it would be replaced by the brain’s constant drip of cerebral spinal fluid. He then reattached her skull using four tiny dissolvable plates made of sugar. Overall, the hemispherectomy took nine hours, and at the very end Renard bandaged Lacy’s head and gently turned her onto her right side, sticking on tape that said “This side up.”

Lacy was released from the hospital a week later.
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Around one hundred children have undergone a similar procedure at Johns Hopkins, and with extensive therapy to help them relearn how to walk, talk, and think, the overwhelming majority of them have flourished.

Hemispherectomies are a drastic but necessary operation for a small group of people, most of them children. Faraneh Vargha-Khadem, a professor of Developmental Cognitive Neuroscience at the University College London Institute of Child Health, has followed up on a large number of children who have undergone hemispherectomy. Her best-known case was Alex, a young boy whose left hemisphere was removed when he was eight and a half years old. Alex was virtually mute before the surgery, and his comprehension of words had developed only to the level of a four-year-old. But around ten months after his left hemisphere was taken out and his antiseizure medication was withdrawn, he began to speak first in single words and later in phrases and then in sentences. Even in the normally dry tones of science journals, you can perceive the researchers’ surprise. “To our knowledge,” they wrote, “no previously reported child has acquired a first spoken language that is clearly articulated, well-structured and appropriate after the age of six years.”

How can a brain do such a thing? At this point in human evolution, there are so many neurons in our brains that the potential number of connections between them is thought to be around 500 trillion. We’ve had these enormous brains for about 200,000 years, and it took us almost all this time (190,000 years) to start opening our skulls and interfering with them. It took another 9,900 years to really start working out how the brain functions. Since 1990 the neuroscience of language has run a course similar to that of animal cognition and language evolution in that it has undergone revolutionary changes. Our picture of language in the brain since then has been transformed almost beyond recognition.

Nothing in the traditional view of how the brain and language function could account for Lacy and Alex. A skeptic might argue that Lacy can talk because her right hemisphere was removed—scientists used to believe that language was located almost entirely on the left side of the brain. But if that were the case, Alex would be forever mute. Indeed, in the last few decades, a number of children have demonstrated that they are able to talk after removal of the left hemisphere. Most of them suffer some kind of deficit, but their language is more than good enough to enable them to get by in the world.

In the past the only way to deduce the workings of the brain was through the successes and mistakes of primitive neurosurgery and “experiments of nature,” cases where unfortunate individuals suffered brain damage from some kind of accident. Observers were able to determine the damage postmortem and then plot in a crude way how it had affected behavior and thinking while the victim was alive.

Phineas Gage is the best-known case study in accidental neuroscience. Gage was a railroad laborer, and in 1848 the inadvertent sparking of some gunpowder sent a bolt of iron shooting through his brain. He survived, but his personality changed completely. He became surly and difficult and struggled with decision making and planning. Gage’s state before and after his injury revealed a great deal about the role of the frontal lobes in the workings of the brain.

Today magnetic resonance imaging and positron-emission tomography allow scientists to peer inside a normal living brain and see how it works in real time. Electroencephalograms, another useful technology, measure the electrical waves that are naturally emitted by the brain. These brain waves change in response to different input, which in a language experiment might include normal and ungrammatical sentences. More recently, neuroscientists have developed a way to keep neurons alive for days at a time in petri dishes. The researchers stimulate the neurons in different ways and watch how they respond.

In the traditional phrenological model, different talents and tendencies existed within separate compartments of the brain, and for a long time people assumed that much of the evidence from brain damage suggested that language existed within specific spaces. But as knowledge about the workings of the brain accumulated, the idea that only one particular part of it was devoted to language progressively weakened and finally was rejected. No neuroscientist has found any specific area or tissue that controls language and language only. There are no obvious neural add-ons in the human brain, and of all its cell types there isn’t one that only humans have.

As recently as twenty years ago it was taught that language specifically resided in Broca’s and Wernicke’s areas on the left side of the brain. It’s hard to even imagine now how confidently that belief was held, because as we know today, language function is spread throughout the brain. According to Fred Dick, a senior lecturer in psychology at Birkbeck, University of London, all the laboratories that have tried to find a language area have been successful in that they have indeed found dozens, even hundreds, of them.
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If you look for activation in any cortex, when language is spoken or comprehended, you will find it. Lieberman’s studies of Parkinson’s patients and Everest climbers, as well as Pinker’s work on the past tense in English, show that there is an overlap between the parts of the brain that are used for speech and the parts that are used for syntax. In addition, the brain areas that are active when learning language are different from the ones that are active when using language once it has been learned. Moreover, different areas are activated depending on the specific language activity, like the comprehension of words, categorizing a word (in a new task versus a learned task), translating between languages, or making decisions about grammar.
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Modern brain imaging has also revealed that the spread of language activation across the two hemispheres of the brain can differ substantially for each individual.
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Clearly, there is no one-to-one correspondence between an area in the brain and all language ability. Although the brain does contain identifiable areas, complicated behaviors are underwritten by many different groups of neurons, and these are linked together to form circuits.
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The activation that takes place within a small, identifiable part of the brain is often a part of a much larger circuit of activation that is distributed throughout the brain. Walking, striking a piano key, speaking, and listening to speech arise from these large neural circuits.
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Summing up our understanding in 2002, Lieberman wrote: “Although our knowledge is at best incomplete, it is clear that many other cortical areas [other than Broca’s and Wernicke’s] and subcortical structures form part of the neural circuits implicated in the lexicon, speech production and perception and syntax, and the acquisition of the motor and cognitive pattern generators that underlie speech production and syntax.” He lists the cerebellum, the prefrontal cortex, frontal regions of the cortex, posterior cortical regions, the anterior cingulate cortex, and regions of the brain traditionally associated with visual perception and motor control.”
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The belief that language was located in the left hemisphere was based primarily on the fact that when people suffered damage to Broca’s area, the aphasia they experienced appeared to destroy a lot of grammatical knowledge. But the data are inconclusive, and as Elizabeth Bates
⁹
and Fred Dick have pointed out, people with Broca’s aphasia are still able to make certain types of grammatical judgments.
¹⁰
In fact, it seems they retain a great deal of knowledge of their language’s grammar, but have trouble accessing it. Moreover, the symptoms of Broca’s aphasia have also been reported in other groups who do not have damage in that part of the brain. Dick adds that the problems that Broca’s patients have can be language-specific (though much of the original testing for Broca’s was done in English, the findings were thought to be true regardless of which language and syntactic system the subject used). While this doesn’t mean that Broca’s area isn’t important for language, it does show that it isn’t the only language-involved area of the brain.

Not only are language and other higher mental abilities distributed throughout the brain, but Broca’s area has been shown to serve other functions as well.
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As Bates and Dick note, “Activation in Broca’s area is observed when subjects plan covert nonspeech mouth movements, make rhythmic judgments, or perform complex sequences with the hands and fingers. In fact Broca’s area is active when the subject merely observes such movements by another human being or reacts to static objects (tools) that are associated with such movements.”
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None of this evidence against the language-is-a-box-in-the-brain model means that language is just a function of a homogeneous general intelligence. Bates explained: “There is no such thing as vanilla cognition…There are variations in computational style and computational power from one region to another, from one layer to another within a single region, and from cell to cell.”
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Also, once a human brain has matured, the distribution of language functions across that brain is not random. Particular areas take on important parts of the overall task of perceiving and understanding language. It is widely accepted that different sides of the brain dominate in the processing of prosody (right hemisphere) versus syntax (left hemisphere). In 2005 Lorraine Tyler and colleagues published an experiment that compared the perception of verbs that were regular (“jump,” “jumped”) and irregular (“think,” “thought”) in their past-tense form. They demonstrated how the sound, meaning, and structure of a word all appear to be processed in different areas of the brain.

Brain imaging showed that in the experimental subjects regular past-tense forms are processed by a neural circuit that includes the left superior temporal gyrus, Wernicke’s area, and connections to the left inferior frontal cortex.
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Irregular verbs, however, take a different path through the brain. It appears as if the stem and affix of the regular past-tense verbs are computed as the words are heard, but the irregulars, which have no special syntactic marking, are treated simply as whole words, like nouns or uninflected verbs. Accordingly, people who suffer brain damage have been shown to have trouble with one type of past-tense verb or the other—but not necessarily both.
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Fine-grained brain imaging reveals that even if parts of the brain, like Broca’s area, perform many nonlanguage functions, they may still be very important for specifically linguistic processing.
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Such findings underline yet again the way that what we experience as a single thing—language, words, tense—arises from an amalgam of more and less general strategies.
¹⁷

Dismissing the principles of phrenology doesn’t rule out the possibility that human children are born with some specialization for language. Those with particular types of brain damage do experience delays in acquiring language. The fact that these children are slowed down suggests that the damaged areas may have been particularly fertile ground for language acquisition before the damage. However, the same children often naturally catch up to a normal level of language use, also suggesting that there are mechanisms that help the brain to recover, to reorganize on the fly. So even if there are parts of the brain that are best suited for language acquisition from birth, other areas can sometimes step in if they fail. The way that a brain can take different routes to the same basic behavior—in this instance, turning language loss into language gain—is called plasticity.