Building Gab: Part Two

In my last post, I traced a debate over the evolution of language. On one side, we have Steven Pinker and his colleagues, who argue that human language is, like the eye, a complex adaptation produced over millions of years through natural selection, favoring communication between hominids. On the other side, we have Noam Chomsky, Tecumseh Fitch, and Marc Hauser, who think scientists should explore some alternative ideas about language, including one hypothesis in which practically all the building blocks of human language were already in place long before our ancestors could speak, having evolved for other functions. In the current issue of Cognition, Pinker and Ray Jackendoff of Brandeis responded to Chomsky, Fitch, and Hauser with a long, detailed counterattack. They worked their way through many features of language, from words to syntax to speech, that they argued show signs of adaptation in humans specifically for language. The idea that almost of all of the language faculty was already in place is, they argue, a weak one.

Chomsky, Fitch, and Hauser have something to say in response, and their response has just been accepted by Cognition for a future issue. You can get a copy here. Chomsky, Fitch, and Hauser argue that Pinker and Jackendoff did not understand their initial paper, created a straw man in its place, and then destroyed it with arguments that are irrelevant to what Chomsky, Fitch, and Hauser actually said.

It was exactly this sort of confusion about language that Chomsky, Fitch, and Hauser believe has dogged research on its evolution. The first step to resolving this confusion, they argue, is to categorize the components of language. They suggest that scientists should focus on two categories, which they call the Faculty of Language Broad (FLB), and the Faculty of Language Narrow (FLN). FLN includes those things that are unique and essential to human language. FLB includes those things that are essential to human language but are not unique. They might be found in other animals, for example, or in other functions of the human mind.

Chomsky, Fitch, and Hauser argue that we don’t actually know yet what belongs in FLN. The only way to find out is to explore the human mind and the minds of animals. But they argue that the road to an understanding of how language evolved must start here. Simply calling all of language an adaptation is a vague and fruitless statement, and one that leaves biologists and linguists unable to work together.

In their effort to portray language as a monolithic whole utterly unique to humans, Pinker and Jackendoff offer up evidence that Chomsky, Fitch, and Hauser consider beside the point. Consider the fact that the human brain shows a different response to speech than to other sounds. Chomsky, Fitch, and Hauser argue that you can’t use the circuitry of the human brain as a simple guide to the evolution of its abilities. After all, some people who suffer brain injuries can lose the ability to read while retaining the ability to write. It would be silly to say that this is evidence that natural selection has altered the human brain because reading provides some reproductive advantage. Animals, Chomsky, Fitch, and Hauser argue, are a lot better at understanding the features of speech sounds than Pinker and Jackendoff give them credit for. In fact, they claim that Pinker and Jackendoff are behind the curve, relying on research that’s years out of date. Given all that’s been discovered about animal minds, Chomsky, Fitch, and Hauser argue that we should assume that any feature of language can be found in some animal until someone shows that it is indeed unique to humans.

There’s a lot that’s fascinating in all of the papers I’ve described in these two posts, but I find them frustrating. Pinker and Jackendoff may have erected a straw man to attack, but I think they can to some extent be forgiven. The 2002 paper by Chomsky, Fitch, and Hauser was murky, and their new paper, which is supposed to clarify it, is a bit of a maze as well. Consider the "almost-there" hypothesis, which they offered up in their 2002 paper. It’s conceivable that FLN contains only one ingredient–a process called recursion, which I describe in my first post. If that’s true, the evolution of recursion may have brought modern language into existence. On the one hand, Chomsky, Fitch, and Hauser claim to be noncommittal about the almost-there hypothesis, saying that we don’t yet know what FLN actually is. On the other hand, they claim there is no data that refutes it. Doesn’t sound very noncommittal to me.

I’m also not sure how meaningful the categories of FLB and FLN are. Consider the case of FOXP2, a gene associated with human language. Chomsky, Fitch, and Hauser point out that other animals have the gene, and that in humans its effects are not limited to language (it’s important in embryo development, too). So it belongs in FLB, because it’s not unique enough to qualify for FLN.

It is true that other animals have FOXP2, but in humans, it has undergone strong natural selection and is significantly different from the versions found in other animals. And just because it acts the human body in other ways doesn’t mean that natural selection couldn’t have favored its effect on human language. Chomsky, Fitch, and Hauser grant that features of language that belong to FLB may have also evolved significantly in humans. But if that’s true, then deciding exactly what’s FLN and what’s not doesn’t seem to have much to offer in the quest to understand the evolution of human language.

For now, the main effect these papers will have will probably be to guide scientists in different kinds of research on language. Some scientists will follow Pinker and Jackendoff, and try to reverse-engineer language. Others will focus instead on animals, and will probably find a lot of new surprises about what they’re capable of. But until they come to a better agreement on what adaptations are, and the best way to study them, I don’t think the debate will end any time soon.