Читать книгу Babel's Dawn - Edmund Blair Bolles - Страница 6

ENTRANCE HALL: BECOMING DIFFERENT

LIKE ALL SCIENCE stories, this one begins with wonder. Over the centuries, many people have noticed an infinite chain of language acquisition. We learned to talk from our parents, who learned from their parents, who learned from their parents—but how did that chain begin? Asked in modern, Darwinian terms, we know that our ape ancestors did not speak, so there must have been a time when members of the human lineage began speaking without learning it from their parents. How did they do that?

Against a wall stands a wax figure of Samuel Johnson, famous as the author of the first great dictionary of the English language. He wears an eighteenth-century wig and a cheap frock coat. Behind him, written on the wall, is a quotation from one of his famous conversations.

Johnson, like many people, tried to explain the birth of language as a miracle, proposing that language began as a product of divine inspiration. The wall quotation reads:

A thousand, nay, a million children could not invent a language. While the organs are pliable, there is not understanding enough to form a language; by the time that there is understanding enough, the organs are become stiff. We know that after a certain age we cannot learn to pronounce a new language.

The argument makes sense. Children don’t have the brains to come up with language; adults don’t have the tongues. But it turns out that Johnson underestimated how creative groups of children can be.

Most languages spring from the abyss of time, the way French and Spanish stem from Latin, which descended from an old Italic language that was one of many offspring of the Indo-European tongue that had ancestors of its own. But there are a group of languages known as Creoles that are much more recent. They were spawned by the children of slaves and indentured servants.

Slaves may have been perfectly articulate when they were captured, but conditions changed. An African Ibo tribesman, for example, might have been dragged to a plantation in the West Indies where he was worked by people who spoke an incomprehensible white-man’s gibberish. The tribesman was surrounded by other slaves from different parts of West Africa who knew nothing of the Ibo language. He was forced to speak a pidgin—a hodgepodge of words without grammatical associations. The obvious solution was to come up with grammatical usages that let people express more complex ideas and relationships than pidgins can organize. A grammatical pidgin is called a Creole language, and they have emerged wherever communities were once forced to communicate only through pidgins. About thirty years ago, it was finally established that Creoles were created by the children of those pidgin-speaking adults.

A statue of a girl who looks about eight years old shows her making the sign for “water” in Nicaraguan Sign Language.

About twenty years ago, a linguist named Judy Kegl (now Judy Shepard-Kegl) happened to be on hand in a Nicaraguan school for deaf children where she was surprised to observe the children create a sign language. A centralized school for teaching deaf children was new to the country. Previously, deaf children tended to lead isolated existences, getting by with a few signs known as home signs, a kind of pidgin for deaf people. The children were brought together in the hope of teaching them proper Spanish, but instead they turned their home signs into a full-blown functioning sign language.

Dictionary Johnson was wrong. When grouped together into a community, human children have it within themselves to take random words from their environment and create a new language. That’s how Creole languages currently spoken in the Caribbean, South America, Hawaii, the Indian Ocean, and Africa began. It is decisive evidence that no miracle is required to produce a new language, and it suggests very strongly that there is some inborn tendency to express ourselves. As Kegl put it, we have a natural “hunger for language.” In other words, language has a biological (and therefore an evolutionary) side to it.

Side by side are statues of Charles Darwin and Alfred Wallace, the co-discoverers of the theory of evolution through natural selection. Wallace hands Darwin an envelope, symbolizing the historical moment when Wallace mailed Darwin a paper setting forth his theory. After years of silence, Darwin was forced to report his ideas publicly.

Darwin had suspected that language was biological, but most people thought that languages were entirely cultural. As late as the 1950s, a commonplace of linguistics held that the fundamental fact of languages was how different they all were. Whenever a new language was discovered, experts assumed that it might be completely unlike any language previously known. They took it for granted that language had begun as a result of invention, a prehistoric event whose birth was lost to discovery and not to be inquired about.

The doctrine of language’s purely cultural nature and origins gave way because of theoretical work by Noam Chomsky, the dominant linguist of the last half of the twentieth century, and because of the fieldwork in Creole languages by another linguist, Derek Bickerton. In his zesty book Bastard Tongues, Bickerton tells how he traveled through the world studying Creoles and their histories until he had the proof that different Creoles had different origins. They are not simply varieties of one common language. He also showed that it was the children who transformed them from pidgins.

How do children accomplish such a feat? Even more fundamentally, how do ordinary children start speaking so effortlessly? No account of language origins is likely to be accepted unless it explains why it is that (with a few tragic exceptions) every human baby in the world starts using language without requiring special training. Meanwhile, no animal, even with extensive drilling, manages to use, at the absolute best, more than a few hundred words.

The most obvious answer to these basic questions is that humans have some kind of instinct for language. By the early 1990s, there was a widespread view that language was entirely instinctive and that no two languages really differed all that much. Chomsky still holds that opinion, but it has become a minority position among researchers into language evolution.

One much disputed point concerns the amount of biological change necessary to produce modern speech. The language-instinct proponents in particular have often favored a single genetic mutation that, in a sudden “big bang,” transformed our ancestors into symbol users. Others, particularly biologists, criticize that view as naive. There is much more to talking than getting the grammar straight, as this tour will show. We had to alter our windpipes, take subtle control of our tongues and lips, tune our ears to vocal sounds, alter our breathing patterns so we could speak for extended periods without becoming giddy, become willing to listen to what was on another’s mind, become willing to tell others what we knew, develop brains able to use thousands of words, master paying joint attention, and obtain a knowledge of grammar. And it was all done by the normal, ceaseless process of changing generations—perhaps almost 475 thousand generations between today and our last common ancestor with chimpanzees.

A picture on the opposite wall shows a chimpanzee dressed in magician’s costume pulling Shakespeare (whose head is visible) from a hat.

The wonder of evolution is that every link along the chain of generations is almost exactly like the one before it and the one after it, yet the start and end of the chain can be very different. In the case of language, we began with an ape and ended with us. All along the way there was a steady mixing of at least three generations—juveniles, parents, and grandparents—and the juveniles always looked pretty much like the grandparents. It was a very slow morphing through a long line of individuals.

There are two natural—and misleading—ways to tell the story of evolutionary change. One focuses on the abstract turning points and finds revolution. For speech origins, revolution means a gateway through which the human lineage passed. On one side were the non-talkers, on the other blabbermouths. Revolutionary speculations are full of references to hopeful monsters and big bangs (or, for the technically minded, saltations ), events that made a knife cut across history and sliced the connection between what came before from what came after. To justify their position, revolutionists point to the many obvious differences between apes and us, including our success at adapting to many eco-niches, our languages, and our moral codes.

Their rivals tell a slow story of continuity. Sure, we talk, but all animals communicate. True, we make machines, but chimpanzees and many other animals use tools as well. Yes, we love, but bonobos give one another reassuring hugs. Stories of continuity put the stress on modification and similarity. They point to logic to justify their claim. You cannot evolve something from nothing, so obviously we must be the result of what came before—tweaked and stretched, but nothing really new.

Both arguments make sense, and both are wrong for the same reason. They overlook evolution’s essential mechanism of change: variation combined with selection.

Variation without selection occurs all the time. Variation happens because the systems for biological reproduction are not exact. The windpipe between mouth and lungs, for example, will differ slightly in every Homo sapiens. Usually the differences average out and the typical windpipe remains stable over time. Occasionally, just by chance, the variations lean more one way than another and the shape of the average body’s breathing organs drift a little. The important truth about variation, with or without drift, is that it is random and tells us nothing about the larger world.

That larger world has its say when it comes to selection. Selection, by the way, is a poor name for what happens. It sounds like somebody or something actively makes a choice, but in fact nothing and nobody is in charge. The process is much like a sporting playoff in which competitors face off and one team ends up as champion. Nobody selected the champion; it just won. Natural success might be a more precise phrase, but at this late date in history Darwin’s term is here to stay.

Selection begins with variation. A variation in a windpipe might be rejected for millions of years, and then suddenly circumstances change and the variation is passed on to another generation as just the right thing. What makes a variation the right thing? Something about the environment must have changed, making what was once an unwelcome trait become a winner. Selection keeps generations of organisms in tune with the environment, even as the environment changes. Selection works like a cruise ship’s stabilizers, making constant, small adjustments so quickly in response to irregularities that the passengers barely notice them. Some people, however, think of evolution as a ship going somewhere and assume that it can make progress. Others think of evolution as getting nowhere and assume that nothing can change.

No more prestigious example of progress-oriented thinking can be found than in Noam Chomsky’s own speculation about language origins. His ideas are unusual because he proposes that language began as a medium for internal thinking rather than for communication. He said in a talk a few years ago:

The simplest account of the “Great Leap Forward” in the evolution of humans would be that the brain was rewired, perhaps by some slight mutation . . . There are speculations about the evolution of language that postulate a far more complex process: first some mutation that permits two-unit expressions, perhaps yielding selectional advantage by reducing memory load for lexical items; then further mutations to permit larger ones; and finally the Great Leap . . . Perhaps the earlier steps really took place, though there is no empirical or serious conceptual argument for the belief. A more parsimonious speculation is that they did not, and that the Great Leap was effectively instantaneous, in a single individual, who was instantly endowed with intellectual capacities far superior to those of others, transmitted to offspring and coming to predominate.

There are many things in this passage likely to trouble anyone familiar with the process of evolution. The joking allusion to the Maoist term “Great Leap Forward” leaves no doubt that this line of thinking is in the revolutionist, evolution-asprogress tradition. On a more technical level, there is all that emphasis on variation rather than selection. The engine of Chomsky’s revolution was mutation. Suddenly we get a variety of individual “who was instantly endowed with intellectual capacities far superior to those of others.” (Remind you of anybody?) But the issue of selection is completely missing. Yet we cannot just assume that the superman wins simply by the nature of his distinctiveness. Remember the warning from the preacher in Ecclesiastes 9:11:

. . . the race is not to the swift, nor the battle to the strong, neither yet bread to the wise, nor yet riches to men of understanding, nor yet favour to men of skill; but time and chance happeneth to them all.

Without selection, time and chance doom the brightest hopes. Eventually the race may go to the swift, but only when there are enough predators to catch the slowpokes. Without selection, time and chance rule the hour.

For us today, the benefits of language are so obvious that it is tempting to downplay selection. We assume that any variation that supports speech, even a little bit, will be favored, but remember that while we talk plenty, other species do not even talk a little. There must be very powerful reasons why time and chance have never brought speech to any other species. Surely lions would be better hunters if they could talk among themselves and develop more promising plans, but they do not speak. Even if Chomsky was right about how the mutation worked, there must have been some reason why a bit of brain rewiring was selected this time around.

The continuitarians can laugh at the revolutionists and their misreading of how evolution works, but they have made a great mistake themselves. Their motto comes from a French wit who said in response to a political upheaval, “The more it changes, the more it’s the same thing.” It was a sardonic cry of despair, picked up by conservatives who like to deny that revolutions change anything, and it carries proponents right back to Ecclesiastes: “Time and chance happeneth to them all.” What they miss is the power of selection to effect great changes over time.

The preacher in Ecclesiastes assumed that green plants, swimming fish, and bird migrations had been there from the beginning, so he could insist that there was nothing new under the sun. We, however, suppose that the world began as a hot, sterile mass orbiting a new sun, so the presence of plants, fish, and birds argues that time and chance can accomplish wonders when you mix selection into the pot.

The most extensive argument for the slow-and-steady position was made by Christine Kenneally in her book The First Word. Unlike Chomsky, who takes language to be a coherent system of syntactical rules, Kenneally sees speech as comprising a “suite” of physical abilities, each of which we have in common with many other animals. She writes:

In most disciplines the focus used to be on the separateness of animals and humans, that gulf being marked most strikingly by language. But over the last few decades, the emphasis has switched to investigating the continuity of life in addition to clarifying the boundaries that lie between species. We no longer have a sense that we are standing apart from all animal life and that language is a discrete, singular ability that isolates us . . . [Many animal researchers] talk in terms of a rough continuum between modern animals and modern humans, describing the differences between them and us as more quantitative than qualitative. Such a continuum . . . is based on the existence of similarities and differences of features important to language.

And Kenneally is quite good at presenting the many things language requires that are found in other animals as well, but she is unlikely to persuade a reader who starts with the idea that there is a qualitative difference between ape and human communication. A list of similarities between the two is apt to be dismissed as noting only secondary features of language, none of which get to the core of what makes human speech unique.

It is in explaining why humans and only humans talk that the inadequacy of both revolutionary and continuitarian accounts become evident. Technically speaking, they are both forced to argue in a circle: Humans alone speak because no other animals do. In the revolutionary case, humans alone speak because no other animal got the appropriate mutation. Why didn’t they get that mutation? They just didn’t. Meanwhile, the continuitarians say humans alone speak because no other animal has taken the requisite set of skills as far as we have. And why haven’t they done so? They just haven’t.

More generally, these circular arguments miss what is the central point of this tour through the natural history of speech. Humans alone speak because we alone need to speak. Language supports something essential in us that is not even trivially necessary for the other species of the world. The revolutionaries were right in arguing that there was a break. Something new appeared under the sun, but they became trapped in their explanatory circle because they did not try to find what had changed that not only made language possible but necessary. If it were not for language, our lineage would have died out on the African plains. Indeed, the other erect, bipedal apes on the grasslands did become extinct. Yet non-talking nonhumans have prospered. Why don’t they need language too? We know from specialized training projects with captive apes that they can use sign language about as well as a two-year-old, yet in the wild they never use gestures to form words. Nor do chimpanzees who have been taught to sign chatter among themselves. That makes for a Tom-Dick-and-Harry trilogy of mysteries.

TOM: How did people come to talk?

DICK: How can children use language so effortlessly?

HARRY: Why don’t any other animals speak at all?

It is the Harry mystery that trips up the continuitarians. They were right when they said that we are an extension of our primate ancestors, but they failed to notice that the difference between our ancestors and us goes far beyond speech. Speech is the essential instrument for holding human communities together, but there is more to being human than using language.

A wall displays a triangle whose corners are labeled “speaker,” “listener,” and “topic.” Arrows point between speaker and listener, and separate arrows point from speaker and listener to topic.

The speech triangle summarizes the community structure that distinguishes human communication. Machines and animals communicate to manipulate one another; two biologists, Richard Dawkins and John Krebs, have even written that animal communication is so manipulative and controlling, so unlike human communication, that they are “tempted to abandon the word communication altogether.” Humans communicate to pilot attention to some topic of joint interest. Apes have a two-way communication structure. To get another’s attention, a chimpanzee might slap the ground. Other apes naturally look toward the unexpected noise, and the first ape can then make a begging gesture or give a look of intimidation. This behavior is typical of procedural communication. The first step, the slap, is followed by a second step, and both steps are focused on manipulating the other.

Humans can beg and intimidate as well, but they can also do things that apes do not do, by using the speech triangle. Its three-sided structure supports a communicative function unknown elsewhere in the animal world: mutual consideration of a topic. When we think with words, we think about something: the topic. When we converse with others, we have a topic in mind even if it keeps changing as the conversation rambles on. The kind of communal knowledge created through the exploration of a topic is the fundamental gift of language. The formal study of language usually concentrates on the abstract elements (notably syntax and symbols) that organize sentences, so linguists rarely worry about how these elements originate. But a look into speech origins quickly shows that the keystone supporting the whole triangle is our ability to join with one another in considering a topic.

Psychologist/anthropologist Michael Tomasello describes an example of the difference between human helpfulness and the rugged individualism of apes:

. . . when a whimpering chimpanzee child is searching for her mother, it is almost certain that all the other chimpanzees in the immediate area know this. But if some nearby female knows where the mother is, she will not tell the searching child, even though she is perfectly capable of extending her arm in a kind of pointing gesture. She will not tell the child because her communicative motives simply do not include informing others of things helpfully.

Why aren’t chimpanzees motivated to help? There is a straightforward, Darwinian explanation for the ape’s mum’s-the-word behavior. Individuals don’t help non-kin. There is nothing in it, no survival or reproductive advantage, for the informed adults to help the whimpering child of another. And yet humans typically do help out whimpering children, even if the child is a stranger. An adult, happening upon a solitary, unknown, whimpering child, is very likely to stop and ask what is wrong, take charge, and stay with the child until the problem is resolved. This activity strikes us as perfectly natural, normal behavior, even though it is contrary to so many practices of other animals.

No, this tour is not about to challenge the theory of evolution, but it does say we need a good evolutionary account of how a species of ape with no motive to assist others outside the family became a species that takes such group helping for granted. How is it that our old behavior—ape behavior—seems shocking? Six million years ago, apes already had the physical ability and the brains to offer some help to one another, yet they did not help. The first part of the rise of speech, therefore, was the evolution of the speech triangle and a willingness to share what you perceive.