4. Only humans, as far as we know, can use metaphor and analogy, although here we are in a gray area: the elusive boundary between thought and language. When an alpha male ape makes a genital display to intimidate a rival into submission, is this analogous to the metaphor “F—k you” that humans use to insult one another? I wonder. But even so, this limited kind of metaphor falls far short of puns and poems, or of Tagore’s description of the Taj Mahal as a “tear drop on the cheek of time.” Here again is that mysterious boundary between language and thought.
5. Flexible, recursive syntax is found only in human language. Most linguists single out this feature to argue for a qualitative jump between animal and human communication, possibly because it has more regularities and can be tackled more rigorously than other, more nebulous aspects of language.
These five aspects of language are by and large unique to humans. Of these, the first four are often lumped together as protolanguage, a term invented by the linguist Derek Bickerton. As we’ll see, protolanguage set the stage for the subsequent emergence and culmination of a highly sophisticated system of interacting parts that we call, as a whole system, true language.
TWO TOPICS IN brain research always seem to attract geniuses and crackpots. One is consciousness and the other is the question of how language evolved. So many zany ideas on language origins were being proposed in the nineteenth century that the Linguistic Society of Paris introduced a formal ban on all papers dealing with this topic. The society argued that, given the paucity of evolutionary intermediates or fossil languages, the whole enterprise was doomed to fail. More likely, linguists of the day were so fascinated by the intricacies of rules intrinsic to language itself that they were not curious about how it may have all started. But censorship bans and negative predictions are never a good idea in science.
A number of cognitive neuroscientists, myself included, believe that mainstream linguists have been overemphasizing the structural aspects of language. Pointing to the fact that the mind’s grammatical systems are to a large extent autonomous and modular, most linguists have shunned the question of how these interact with other cognitive processes. They profess interest solely in the rules that are fundamental to the brain’s grammatical circuits, not how the circuits actually work. This narrow focus removes the incentive to investigate how this mechanism interacts with other mental capacities such as semantics (which orthodox linguists don’t even regard as an aspect of language!), or to ask evolutionary questions about how it might have evolved from preexisting brain structures.
The linguists can be forgiven, if not applauded, for their wariness of evolutionary questions. With so many interlocking parts working in such a coordinated manner, it’s hard to figure out, or even imagine, how language could have evolved by the essentially blind process of natural selection. (By “natural selection,” I mean the progressive accumulation of chance variations that enhance the organism’s ability to pass on its genes to the next generation.) It’s not difficult to imagine a single trait, such as a giraffe’s long neck, being a product of this relatively simple adaptive process. Giraffe ancestors that had mutant genes conferring slightly longer necks had better access to tree leaves, causing them to survive longer or breed more, which caused the beneficial genes to increase in number down through the generations. The result was a progressive increase in neck length.
But how can multiple traits, each of which would be useless without the other, evolve in tandem? Many complex, interwoven systems in biology have been held up by would-be debunkers of evolutionary theory to argue for so-called intelligent design—the idea that the complexities of life could only occur through divine intervention or the hand of God. For example, how could the vertebrate eye evolve via natural selection? A lens and a retina are mutually necessary, so each would be useless without the other. Yet by definition the mechanism of natural selection has no foresight, so it couldn’t have created the one in preparation for the other.
Fortunately, as Richard Dawkins has pointed out, there are numerous creatures in nature with eyes at all stages of complexity. It turns out there is a logical evolutionary sequence that leads from the simplest possible light-sensing mechanism—a patch of light-sensitive cells on the outer skin—to the exquisite optical organ we enjoy today.
Language is similarly complex, but in this case we have no idea what the intermediate steps might have been. As the French linguists pointed out, there are no fossil languages or half-human creatures around for us to study. But this hasn’t stopped people from speculating on how the transition might have come about. Broadly speaking, there have been four main ideas. Some of the confusion between these ideas results from failing to define “language” clearly in the narrow sense of syntax versus the broader sense that includes semantics. I will use the term in the broader sense.
THE FIRST IDEA was advanced by Darwin’s contemporary Alfred Russel Wallace, who independently discovered the principle of natural selection (though he rarely gets the credit he deserves, probably because he was Welsh rather than English). Wallace argued that while natural selection was fine for turning fins into feet or scales into hair, language was too sophisticated to have emerged in this way. His solution to the problem was simple: Language was put into our brains by God. This idea may or may not be right but as scientists we can’t test it, so let’s move on.
Second, there’s the idea put forward by the founding father of modern linguistic science, Noam Chomsky. Like Wallace, he too was struck by the sophistication and complexity of language. Again, he couldn’t conceive of natural selection being the correct explanation for how language evolved.
Chomsky’s theory of language origins is based on the principle of emergence. The word simply means the whole is greater—sometimes vastly so—than the mere sum of the parts. A good example would be the production of salt—an edible white crystal—by combining the pungent, greenish, poisonous gas chlorine with the shiny, light metal sodium. Neither of these elements has anything saltlike about it, yet they combine into salt. Now if such a complex, wholly unpredictable new property can emerge from a simple interaction between two elementary substances, then who can predict what novel unforeseen properties might emerge when you pack 100 billion nerve cells into the tiny space of the human cranial cavity? Maybe language is one such property.
Chomsky’s idea isn’t quite as silly as some of my colleagues think. But even if it’s right, there’s not much one can say or do about it given the current state of brain science. There’s simply no way of testing it. And although Chomsky doesn’t speak of God, his idea comes perilously close to Wallace’s. I don’t know for sure that he is wrong, but I don’t like the idea for the simple reason that one can’t get very far in science by saying (in effect) something miraculous happened. I’m interested in finding a more convincing explanation that’s based on the known principles of organic evolution and brain function.
The third theory, proposed by one of the most distinguished exponents of evolutionary theory in this country, the late Stephen Jay Gould, argues that contrary to what most linguists claim, language is not a specialized mechanism based on brain modules and that it did not evolve specifically for its most obvious present purpose, communication. On the contrary, it represents the specific implementation of a more general mechanism that evolved earlier for other reasons, namely thinking. In Gould’s theory, language is rooted in a system that gave our ancestors a more sophisticated way to mentally represent the world and, as we shall see in the Chapter 9, a way to represent themselves within that representation. Only later did this system get repurposed or extended into a means of communication. In this view, then, thinking was an exaptation—a mechanism that originally evolved for one function and then provided the opportunity for something very different (in this case language) to evolve.
We need to bear in mind that the exaptation itself must have evolved by conventional natural selection. Failure to appreciate this has resulted in much confusion and bitter feuds. The principle of exaptation is not an alternative
