FoxP2 Work Contradicts Idea of a Universal Grammar

At the Utrecht conference there was some discussion about the FoxP2 gene that I have been slow to report because I have been trying to get the story straight. I have had a couple of exchanges with Morten Christiansen about his presentation and with his help I think I understand what he was talking about. The basic argument is that genes shape the brain and the brain shapes the way language is learned, thus genes like FoxP2 contribute the way language is learned. The idea changes the role I’ve seen discussed for FoxP2.

Christiansen is a vocal advocate for the position that language has adapted to the brain, rather than the brain adapting to language. This blog has been generally appreciative of Christiansen’s position, although sometimes the quarrel over general-learning versus specific-language-learning can become so refined that it sounds like the medieval scholastics arguing over the proper terminology for transubstantiation. Yet the implications of the dispute are important for this blog. What sort of evolving did the brain do before language could appear? What sort of constraints on language were imposed by the way the brain shaped cultural evolution? Generative grammarians interested in the origins of language look for an explanation of how the universal grammar might have evolved, while Christiansen denies that a universal grammar ever did evolve. So more than scholastic niceties are at stake.

The basic premise of Christiansen’s argument that language was shaped by the brain is that one generation of speakers speak language L. The listeners modify L so that it is easier to speak and remember, giving us L₁, which is modified by further speakers producing L₂. For example, Christiansen writes me about work he has done with Florencia Reali showing, “that when a language is introduced with no word order, consistent word order emergences by way of cultural evolution of language.”

As an example of the way the brain affects language, Christiansen looked at sequential learning, which is the ability to organize discrete elements occurring in a sequence. Notice that phrase discrete elements. In language these case be phrases or clauses rather than words, so Christiansen is not challenging the generative grammarian’s most sacred proposition, that sentences are hierarchically structured rather than being strings of words placed one after another.

If language is learned rather than built into us, sequential learning becomes critical. The listener has to be able to discover the basis of the sequential organization.  Christiansen did work early in this century (reported in 2001) in which he found that non-human primates are surprisingly bad at sequential learning of hierarchically ordered sequences.

Sufferers from strokes sometimes develop agrammatic aphasia, in which they are no longer able to speak syntactically. Christiansen has done work with these people and found that they have trouble with sequential learning.

There are some a priori reasons for thinking FoxP2 might be important in sequential learning. The cortical-striatal system in the brain is “implicated” in sequential learning and FoxP2 is important for the development of the cortical striatal system. So Christiansen invstigated. He studied 159 8th graders. (For readers, not familiar with American schools, 8th grade students are typically about 13 years old.) 100 were normal language learners; 59 of them had language impairment, although their non-verbal IQs were similar to those of the other group.

DNA tests looked at one part of the FoxP2 gene. A typical gene has a molecule symbolized by T; atypical genes can be symbolized by C. As each person’s genome gets a gene from each parent, the genotypes can be classed as TT, TC, or CC. The DNA tests found that:

• 70% of TT students had normal language, 30% were language impaired;
• 70% of CC students had impaired language; 30% were normal;
• 51% of TC students had normal language; 49% were language impaired.

This data is pretty clear. Language impairment does not come only from an abornormality in FoxP2, but much of it does.

Christiansen also conducted a sequential learning study with the students and found that the CC students had a much tougher time learning the task than the TT or CT. Thus, the FoxP2 gene that is associated with language learning problems is also associated with difficulties in a non-verbal, sequential learning task. This is the kind of finding expected by people (like Christiansen) who do not believe that speech origins depended on the evolution of language-specific qualities. It is one more blow to those who believe that there is a universal grammar that rests on language specific abilities.

Comments

[S]

It's really great to see you discussing Christiansen's work here.

[Paul Strand]

I have a question about fox p2 and genetic influences in general. Is it possible that an individual living in an environment that is “poor” with respect providing learning opportunities may experience not only poor learning but also genetic changes? I ask because of a recent study showing that genetic differences emerged across mice resulting from a mere two-week change in diet. Mice fed a typical chimp diet developed chimp-like genetic markers while those fed a typical human diet developed human-like genetic markers (see below link).

I know little about genetics, but might it be that fox p2 gene expression is similarly a product of environmental differences?

Thanks for any input you can provide.

You Are What You Eat: Some Differences Between Humans And Chimpanzees Traced To Diet
http://www.sciencedaily.com/releases/2008/01/080130092139.htm
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BLOGGER: Thanks for the ref. The workings of FoxP2 are unusually subtle because the gene triggers other genes. We are going to be learning details about its operation for years to come. And surely the environment shapes this gene's workings, since pretty much all genes respond to the environment.

[Paul Strand]

Follow up question: Doesn't a finding like the one regarding mice that I cited above throw into doubt the practice of estimating the genetic similarities between species?

It seems to me that one conclusion of that study is that you can alter that estimate by changing the environment of the animal in question.

That is to say: If you want to increase the degree to which mice share genetic similarities with humans, and reduce the shared genetics with chimps, feed them a human diet rather than a chimp diet.

It seems, then, that the idea of firm genetic relationships across species is a myth--or at least has been overstated.

Is that a logical conclusion?
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BLOGGER: I don't think the paper was quite as radical as you are suggesting. By my reading of the diet report, it produced a number of physiological changes, some of them changes in the genetic response to the new nutritional environment. But I see no evidence in the story that the diet changed the genes themselves. (That would be a very big finding, giving Lamarck's theory a bigger boost.)

[gregorylent]

much prefer the yogic view of this which takes into account consciousness .. of course, no western scientist could maintain funding or tenure to suggest such a thing ...

a very sophisticated understanding of speech, mind, consciousness, body (sanskrit word is "vak") which rather puts mr. christiansen in a decidedly inferior position ..

[brainfart]

Gregorylent, while I don't disagree that consciousness is important to language, you don't say how it is important, other than it is "very sophisticated." Could you please elaborate on how Christiansen's ideas are lacking in terms of consciousness?

[JanetK]

Paul Strand - it may sound like they are saying that the genes changed but that is not what is being said. Environment can have 2 adaptive effects on how genes are used but they do not change the genes themselves. You need to look at gene expression and epigenetics to understand these two ways. When genes are actually changed, this is called a mutation. Mutations are rare and caused by things like radiation not diet. They are random and usually harmful not adaptive. I hope this can point you in the right direction to finding material that can help you understand genetics.