Now they've gone and done it. They took a human gene thought to be partly responsible for language and stuck it in a mouse! This gene is called the FOXP2. In 1998, it was pinpointed as the cause of a genetic language defect in a large London family, and ever since then it's caused a bit of a stir for evolutionary biologists and linguists alike.
You can get the full results of the study from this scientific article, or I'll just sum up a few of the more interesting points for you.
- The human version of the FOXP2 gene substitutes perfectly for the mouse version, with the only apparent effects showing up in the brain.
- Humanized mice grew more nerve cells with more complex structure in their basal ganglia, an area known to be important for human language.
- The whistles of baby mice separated from their mothers were slightly lower in pitch among mice with the human gene.
- Humanized mice showed decreased exploratory behavior and lower concentrations of dopamine in the brain.
- The overall effects of giving mice the human FOXP2 gene were in the opposite direction from impairing one of their FOXP2s (which in humans causes language impairment).
Here's a nice video summary as well. Very helpful in case you feel a little lost or just to get a better grasp on the whole thing.