Babel's Dawn. Edmund Blair Bolles

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СКАЧАТЬ 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 СКАЧАТЬ