Modern genetic analyses have told us a great deal about many aspects of the human body and mind. However, genetics has been relatively slow in breaking into the study of language. As I have mentioned before, a few years ago resarchers reported that a damaged version of the gene FOXP2 was responsible for the language impairments in the KE family. This sounds more helpful than it really was, since it turns out that even some reptiles have versions of the FOXP2 gene. In humans, FOXP2 isn’t just expressed in the brain — it’s expressed in the gut as well. This means that there is a lot more going on than just having FOXP2 or not.
Over the weekend, researchers presented new data at the Boston University Conference on Language Development that hones in on what, just exactly, FOXP2 does.
It turns out that there is a certain amount of variation in genes. One type of variation is a Single Nucleotide Polymorphism (SNP), which is a single base pair in a string of DNA that varies from animal to animal within a species. Some SNPs may have little or no effect. Others can have disastrous effects. Others are intermediate. The Human Genome Project simply cataloged genes. Scientists are still working on cataloging these variations. (This is the extent of my knowledge. If any geneticists are reading this and want to add more, please do.)
The paper at BUCLD, written by J. Bruce Tomblin and Jonathan Bjork of the University of Iowa and Morten H. Christiansen of Cornell University, looked at SNPs in FOXP2. They selected 6 for study in a population of normally developing adolescents and a population of language-impaired adolescents.
Two of the six SNPs under study correlated well with a test of procedural memory (strictly speaking, one correlation was only marginally statistically significant). One of these SNPs predicted better procedural memory function and was more common in language-normal adolescents; the other predicted worse procedural memory function and was more common in language-impaired adolescents.
At a mechanistic level, the next step will be understanding how the proteins created by these different versions of FOXP2 do. From my perspective, I’m excited to have further confirmation of the theory that procedural memory is important in language. More importantly, though, I think this study heralds a new, exciting line of research in the study of human language.
(You can read the abstract of the study here.)