This is the title of an item in "Nature science update", and there were many other items with this kind of title lately [6 Oct 2001]. This is based on an article in Nature, in which a gene that causes various deficiencies, including linguistic deficiencies, was identified.
First, history: the family in which the defective gene was found was described in the beginning of the 90's by Myrna Gopnik (after somebody else found them). She claimed that individuals in this family show language-specific deficiencies, and even claimed that these deficiencies were in particular grammatical categories. Since the defect was clearly caused by a mutation in a single-gene (because of the pattern of inheritance), this was taken as a proof for a gene for grammar.
This story have been debunked by a study by other group of researchers in 1995 (Vargha-Khadem, F.; Watkins, K.; Alcock, K.; Fletcher, P. & Passingham, R. (1995) Praxic and nonverbal cognitive deficits in a large family with a genetically transmitted speech and language disorder. Procedures of the National Academy of Science USA 92, 930-3. ). The full abstract is appended below. This group found that the deficiencies, which result from the mutation, are very wide-range, including problems with movement of the face and mouth, and other cognitive deficiencies. They also show that the deficiencies in language are also much broader than the ones described by Myrna Gopnik. It was generally believed to debunk the story, and gave a good reason to hope that this is the last that we hear about this "gene for grammar" story.
It is important to note that Vargha-Khadem et al did not challenge the assertion that the deficiencies are caused by a mutation in a single gene. This was never in doubt. What they challenged was the assertion that this is a grammar-specific gene.
The current [6 Oct 2001] noise is a result from a study that identifies the gene that is mutated in this family (and another individual). However, since the fact that it is a single gene was never in doubt, just identifying it should not affect the question whether it is grammar or language specific. However, that doesn't stop the hype.
It starts from the article itself (A forkhead-domain gene is mutated in a severe speech and language disorder, Kai et al, Nature, 413, 519-523, 2001). The full abstract is given below. In both the title and abstract, the authors mention disorders in "speech and language", but not other deficiencies. They thus create a strong impression that the gene is language-specific. The other deficiencies are mentioned in the body of the paper, but most of readers form their impression from the title and abstract, and hence be misled by the way the article is written.
Another interesting point in the article is that they mention that some of the members of the family have language disorders without cognitive deficits, or with minimal cognitive deficits. However, these members also have problems with movements of face and mouth, which makes it extremely difficult for them to speak, which is quite likely to cause deficiencies in language. This is not mentioned in the article, and is also ignored in the commentaries.
Commentaries are obviously even more misleading. For example, the item in Nature science update declares it is a "language gene" in its title. The debunking of the original story appears around the middle of the item, and it even mentions a reference to it as the "cold fusion" of psychology. However, what it does not make clear is that identifying the exact gene does not change the status of gene as a "language gene". In fact, it strongly implies that the identification does change the status, because otherwise why does the "cold fusion" of the field worth a discussion? This implication is common in all the commentaries.
Some commentaries examples:
[10Mar2002] The latest issue of brain contains an article from the same authors which further debunks the idea of "language gene (Behavioural analysis of an inherited speech and language disorder: comparison with acquired aphasia K. E. Watkins, N. F. Dronkers and F. Vargha-Khadem, Brain, Vol. 125, No. 3, 452-464, March 2002). This article, of course, is going to get much less hype. There is also additional article analyzing the brain structure associated with the problem.
[17Aug2002] Nature just published on line an article which compares the sequence of the gene across species and within humans (title and first paragraph are attached below). The article itself is already pretty misleading. The title says: "Molecular evolution of FOXP2, a gene involved in speech and language", (no mention of orofacial praxis and intellectual problems). The first paragraph (which is the abstract in Nature) introduces the gene this way: "FOXP2 is the first gene relevant to the human ability to develop language". The next sentence describes the abnormalities as "severe articulation difficulties accompanied by linguistic and grammatical impairment", and two sentences down it says "Thus, two functional copies of FOXP2 seem to be required for acquisition of normal spoken language." In the first paragraph there is no mention of other abnormalities. They don't actually say it is not associated with other abnormalities, but pretty strongly imply it. It is only in the middle of the article that they come around to mention that the gene is associated with orofacial movements. The article contains some interesting data, but the only reasonable conclusions is what the authors say in the last senetence of the abstract: " Here we show that human FOXP2 contains changes in amino-acid coding and a pattern of nucleotide polymorphism, which strongly suggest that this gene has been the target of selection during recent human evolution."
Nature web page has a Science Update about the article, titled "Gene leaves apes speechless", with sub-title "Great apes lack nuts and bolts of language gene." The first sentence repeats the reference to "language gene". Later speech problems are mentioned, but not oro-facial abnormalities. The commentary in Science is also quite misleading. The title is "'Speech Gene' Tied to Modern Humans", and the second sentence refers to the gene as "the first gene implicated in the ability to speak". It describes the disorder as "wide range of speech and language disabilities", but there is no mention of orofacial abnormalities or intellectual problems.
It is fair to say that by now the fact that it is the effect on orofacial movements that is important seem to be acknowledged more often. For example, The Seattle Times headline with "Study: Gene mutations led to human language" (a piece apparently taken from the Washington Post) . The third paragraph says:" A mounting body of research suggests that the mutant gene conferred on ancestors of modern humans a much finer degree of control over muscles of the mouth and throat, possibly giving those ancestors a rich, new palette of sounds that could serve as the foundation of language." Ofcourse, the "Mounting body" currently does not contain any evidence at all. All we is that a defective allele of gene cause oro-facial problems, and there is no other relevant evidence. The same journalist headlines a very similar piece with "Gene is linked to dawn of language" in the The International Herald .
The New-York Time, though, still sticks to the "language gene". The title of the article is "Language Gene Is Traced to Emergence of Humans", and in the fourth paragraph the gene is described as "the first human gene involved specifically in language." It does explains down the article that the main problem is controlling throat and mouth, but to compensate for this it add spurious claims, e.g. that one of the mutations in the gene "gives it a new role in the signaling circuitry of human cells", which is evidence free (maybe it is supposed to be based on the speculation in the article that one of the mutations creates a phosphorilation site).
[5Apr2004] Here is an item on the BBC news page, which tells that the foxp2 is "thought to be responsible for speech and language skills."
[5Apr2004]
To make it more fun, the researchers of birds brain and birdsong jump on the bandwagon too. The latest issue of the jorunal of neuroscience contains two articles that propagate the myth of human-speech-like-bird-song, and conflate it with the language-gene myth. In the articles themselves they are relatively moderate, refering to the gene as "monogenetic locus of a human speech disorder" (Teramitsu et al, abstract) and "first gene linked to human speech" ((Haesler et al, abstract). They are less modest in news releases. For example, in this university news release, one of the principle authors of Haesler et al, Jarvis, says:
"In affected humans, the mutation causes a very specific dysfunction," said Jarvis. "These people have largely normal motor coordination, but an inability to correctly pronounce words or form them into grammatically correct sentences. What's more, they have trouble understanding complex language."How does "largely normal motor coordination" fits with orofacial praxic (in Vargha-Khadem et al)? It doesn't, but this way the story sounds better. In this press release by Max Planck Society they also don't have doubts:
Mutations in the so-called FOXP2 gene are associated with a specific speech deficit, affecting articulation and comprehension of language.So we have a "specific speech deficit". In this university release (talking with the principle author of Teramitsu et al) they are slightly less gross:
A study published in 2001 revealed a single mutation in FoxP2 in each member of a family in England with a severe speech disorder; many members of this family, over three generations, have the speech disorder, and each of these family members has the mutation, while those family members without the speech disorder do not have this mutation.I.e. they don't say explicitly that it is only speech, they leave it to the reader to form the impression.
These articles and releases also mislead the readers about the relation between human speech and bird song (See here for discussion).
==============================================================
Yehouda Harpaz
6 Oct 2001
============================================================
----------- The article that debunked the grammar and language specificity of the gene
A pronounced speech and language disorder affecting half of the 30 members of the four-generational KE family has been attributed by some researchers to a specific defect in the generation of morphosyntactic rules. The reported selectivity of the impairment has led to the view that the affected members suffer from a grammar-specific disorder. Our investigations of the same KE family indicate that the inherited disorder has a broad phenotype which transcends impaired generation of syntactical rules and includes a striking articulatory impairment as well as defects in intellectual, linguistic, and orofacial praxic functions generally. Although the evidence from this family thus provides no support for the existence of "grammar genes," their linguistic difficulties do constitute a prominent part of their phenotype. Investigations of the neural and genetic correlates of their disorder could therefore uncover important clues to some of the bases of the primary human faculties of speech and language.
Kai, C.S.L., Fisher, S.E., Hurst, J.A., & Vargha-Khadem, F. (2001). A forkhead-domain gene is mutated in a severe speech and language disorder. Nature. 413: 519-523.
Individuals affected with developmental disorders of speech and language have substantial difficulty acquiring expressive and/or receptive language in the absence of any profound sensory or neurological impairment and despite adequate intelligence and opportunity. Although studies of twins consistently indicate that a significant genetic component is involved, most families segregating speech and language deficits show complex patterns of inheritance, and a gene that predisposes individuals to such disorders has not been identified. We have studied a unique three-generation pedigree, KE, in which a severe speech and language disorder is transmitted as an autosomal-dominant monogenic trait. Our previous work mapped the locus responsible, SPCH1, to a 5.6-cM interval of region 7q31 on chromosome 7 (ref. 5). We also identified an unrelated individual, CS, in whom speech and language impairment is associated with a chromosomal translocation involving the SPCH1 interval. Here we show that the gene FOXP2, which encodes a putative transcription factor containing a polyglutamine tract and a forkhead DNA-binding domain, is directly disrupted by the translocation breakpoint in CS. In addition, we identify a point mutation in affected members of the KE family that alters an invariant amino-acid residue in the forkhead domain. Our findings suggest that FOXP2 is involved in the developmental process that culminates in speech and language.
Nature AOP, published online 14 August 2002; doi:10.1038/nature01025
Molecular evolution of FOXP2, a gene involved in speech and language
WOLFGANG ENARD*, MOLLY PRZEWORSKI*, SIMON E. FISHER†, CECILIA S. L. LAI†, VICTOR WIEBE*, TAKASHI KITANO*, ANTHONY P. MONACO† & SVANTE PÄÄBO*
* Max Planck Institute for Evolutionary Anthropology, Inselstrasse 22, D-04103 Leipzig, Germany
† Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
Correspondence and requests for materials should be addressed to S.P. (e-mail: paabo_eva.mpg.de). FOXP2 cDNA sequences of the mouse, rhesus macaque, orang-utan, gorilla, chimpanzee and human have GenBank accession numbers AY079003, AF512950, AF512949, AF512948, AF512947 and AF337817, respectively. Accession numbers for genomic sequences for the twenty humans, two chimpanzees and one orang-utan are AF515031–AF515050, AF515051–AF515052 and AF515053, respectively.