to natural selection, as Gould’s critics believe, but actually complements and expands its scope and range of applicability. For instance, feathers originally evolved from reptilian scales as an adaptation to provide insulation (just like hair in mammals), but then were exapted for flight. Reptiles evolved a three-bone multihinged lower jaw to permit swallowing large prey, but two of these three bones became an exaptation for improved hearing. The convenient location of these bones made possible the evolution of two little sound-amplifying bones inside your middle ear. No engineer would have dreamed of such an inelegant solution, which goes to illustrate the opportunistic nature of evolution. (As Francis Crick once said, “God is a hacker, not an engineer.”) I will expand on these ideas about jawbones transforming into ear bones at the end of this chapter.
Another example of a more general-purpose adaptation is the evolution of flexible fingers. Our arboreal ancestors originally evolved them for climbing trees, but hominins adapted them for fine manipulation and tool use. Today, thanks to the power of culture, fingers are a general-purpose mechanism that can be used for rocking a cradle, wielding a scepter, pointing, or even counting for math. But no one—not even a naive adaptationist or evolutionary psychologist—would argue that fingers evolved because they were selected for pointing and counting.
Similarly, Gould argues, thinking may have evolved first, given its obvious usefulness in dealing with the world, which then set the stage for language. I agree with Gould’s general idea that language didn’t originally evolve specifically for communication. But I don’t like the idea that thinking evolved first and language (by which I mean all of language—not just in the Chomskian sense of emergence) was simply a byproduct. One reason I don’t like it is that it merely postpones the problem rather than solving it. Since we know even less about thinking and how it might have evolved than we do about language, saying language evolved from thought doesn’t tell us very much. As I have said many times before, you can’t get very far in science by trying to explain one mystery with another mystery.
The fourth idea—diametrically opposed to Gould’s—was proposed by the distinguished Harvard University linguist Steven Pinker, who declares language to be an instinct, as ingrained in human nature as coughing, sneezing, or yawning. By this he doesn’t mean it’s as simple as these other instincts, but that it is a highly specialized brain mechanism, an adaptation that is unique to humans and that evolved through conventional mechanisms of natural selection expressly for communication. So Pinker agrees with his former teacher Chomsky in asserting (correctly, I believe) that language is a highly specialized organ, but disagrees with Gould’s views on the important role played by exaptation. I think there is merit to Pinker’s view, but I also think his idea is far too general to be useful. It is not actually wrong, but it is incomplete. It seems a bit like saying that the digestion of food must be based on the first law of thermodynamics—which is true for sure, but it’s also true for every other system on earth. The idea doesn’t tell you much about the detailed mechanisms of digestion. In considering the evolution of any complex biological system (whether the ear or the language “organ”), we would like to know not merely that it was done by natural selection, but exactly how it got started and then evolved to its present level of sophistication. This isn’t as important for a more straightforward problem like the giraffe’s neck (although even there, one wants to know how genes selectively lengthen neck vertebrae). But it is an important part of the story when you are dealing with more complex adaptations.
So there you have it, four different theories of language. Of these we can discard the first two—not because we know for sure that they are wrong, but because they can’t be tested. But of the remaining two, who’s right—Gould or Pinker? I’d like to suggest that neither of them is, although there’s a grain of truth in each (so if you are a Gould/Pinker fan, you could say they were both right but didn’t take their arguments far enough).
I would like to propose a different framework for thinking about language evolution that incorporates some features of both but then goes well beyond them. I call it the “synesthetic bootstrapping theory.” As we shall see, it provides a valuable clue to understanding the origins of not only language, but also a host of other uniquely human traits such as metaphorical thinking and abstraction. In particular, I’ll argue that language and many aspects of abstract thought evolved through exaptations whose fortuitous combination yielded novel solutions. Notice that this is different from saying that language evolved from some general mechanism such as thinking, and it also differs from Pinker’s idea that language evolved as a specialized mechanism exclusively for communication.
NO DISCUSSION OF the evolution of language would be complete without considering the question of nature versus nurture. To what extent are the rules of language innate, and to what extent are they absorbed from the world early in life? Arguments about the evolution of language have been fierce, and the nature-versus-nurture debate has been the most acrimonious of all. I mention it here only briefly because it has already been the subject of a number of recent books. Everyone agrees that words are not hardwired in the brain. The same object can have different names in different languages—“dog” in English, “chien” in French, “kutta” in Hindi, “maaa” in Thai, and “nai” in Tamil—which don’t even sound alike. But with regard to the rules of language, there is no such agreement. Rather, three viewpoints vie for supremacy.
In the first view, the
While these two models certainly capture some aspect of language acquisition, they cannot be the whole story. After all, apes, housecats, and iguanas have neural networks in their skulls, but they do not learn language even when raised in human households. A bonobo ape educated at Eton or Cambridge would still be an ape without language.
According to the third view, the
I favor this third view because it is the one most compatible with my evolutionary framework, and is supported by two complementary facts. First, apes cannot acquire true language even when they are treated like human children and trained daily in hand signs. They end up being able to sign for something they need right away, but their signing lacks generativity (the ability to generate arbitrarily complex new combinations of words), function words, and recursion. Conversely, it is nearly impossible to prevent human children from acquiring language. In some areas of the world, where people from different language backgrounds must trade or work together, children and adults develop a simplified pseudo-language—one with a limited vocabulary, rudimentary syntax, and little flexibility—called a pidgin. But the first generation of children who grow up surrounded by a pidgin spontaneously turn it into a creole—a full-fledged language, with true syntax and all the flexibility and nuance needed to compose novels, songs, and poetry. The fact that creoles arise time and time again from pidgins is compelling evidence for an LAD.
These are important and obviously difficult issues, and it’s unfortunate that the popular press often oversimplifies them by just asking questions like, Is language mainly innate or mainly acquired? Or similarly, Is IQ determined mainly by one’s genes or mainly by one’s environment? When two processes interact linearly, in ways that can be tracked with arithmetic, such questions can be meaningful. You can ask, for instance, “How much of our profits came from investments and how much from sales?” But if the relationships are complex and nonlinear—as they are for any mental attribute, be it language, IQ, or creativity—the question should be not, Which contributes more? but rather, How do they interact to create the final product? Asking whether language is mainly nurture is as silly as asking whether the saltiness of table salt comes mainly from chlorine or mainly from sodium.
The late biologist Peter Medawar provides a compelling analogy to illustrate the fallacy. An inherited disorder
