Thursday, 12 November 2009

FOXP2 Gene And Ramifying Roots Of Language

Here is news of a very important paper indeed. I've given the url for the Wired article as it is a clear and simple in-road, but there is also good info on the John Hawks weblog (see this blog's side-bar) and the source articles and commentary by Pasko Rakic are in this week's NATURE (vol. 462 pp. 213-217, and pp. 169-170). Lead authors are Genevieve Konopka and Dan Geschwind, of UCLA.

The work concerns the gene FOXP2 - star of chapter 2 in my book, THE LANGUAGE GENE THAT WASN'T. Most will recall that FOXP2 is at the root of an extraordinary speech AND language disorder in an extended London family, that it has accumulated two mutations inside the last 200,000 years (compared to the chimp), that it appears to have come under considerable selection pressure, and that it codes for a protein called a transcription factor which, when released, targets a range of genes under its control and regulates their activity. In this way, FOXP2, while not being the "language gene" itself, is some sort of master controller of a whole orchestra of genes, all or many of which may be part responsible for our unique human language faculty. The question, ever since the discovery of FOXP2, is "what are the members of this orchestra and what do they do?"

Now Geschwind and co. are beginning to supply the answer - thanks to some ultra-modern genomics technology as wielded by Todd Preuss at Emory University. Basically, they gene-engineered human brain cells in which they could either turn FOXP2 on or off, or substitute human for chimp FOXP2 and turn it on or off. The cell lines could be interrogated to see exactly which genes were targeted by the different versions of FOXP2. Human and chimp FOXP2 behaved very differently in the way they regulated their down-stream orchestras. They discovered 116 genes whose regulation seemed connected only to the activity of the human form of FOXP2. Many of them were active in the brain, others in non-nervous system tissue and also cranial structures associated with language function. As they say: "FOXP2 has been the window, but the network is going to be the story". Now that they have drawn the network - the subservient genetic orchestra - they can look at each gene to determine its function and, hopefully, shed more and more light on what underpins language. They have, so far, discovered 5 genes in the network - AMT, C6orf48, MAGEA10, PHACTR2, and SH3PXD2B - which appear to have been positively selected and no doubt these will be among their first investigations as to function.

This is an incredibly important and exciting step and opens the way to a methodical and purposeful slog through the genome to put the complex picture of the genetic foundations of language together. This will be a space well worth watching!

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