Scientists working with song birds have uncovered the genetic basis of human speech.
Sebastian Haesler and his colleagues, writing in the journal PLoS Biology, have shown that a gene called FoxP2, which is expressed in a part of the songbird's brain known as area X, is essential for young birds to learn their songs. Levels of the gene increasing during the time when the birds are acquiring and adapting their songs. But to find out whether the gene is actually responsible for the process the team made a genetically modified virus containing the genetic "mirror image" of FoxP2.
When this virus was injected into a young bird's brain it had the effect of switching off the FoxP2 gene and preventing it from being expressed in that part of the nervous system. And when the team injected young, three week old, zebra finches with the virus and then paired them up with an older "tutor" bird they managed at best to learn only incomplete and inaccurate versions of their teachers' songs. But uninjected control birds, or birds injected with a virus that left the FoxP2 gene unaffected, imitated their tutors much more faithfully. The results bear a striking similarity to a human condition that is caused by inheriting a defective version of the same gene that was knocked out in the birds - FoxP2. Subjects with the condition have difficulties with the production of fluent speech and grammar, suggesting that the present study might hold the key to better understanding the neural basis of how we learn and produce language.