Photo: Bemep (Flickr)
You can say that “X marks the spot” when talking about bird song. That’s because scientists studying zebra finch brains have now identified about two thousand vocalization genes in a brain region of the basal ganglia known as Area X.
2000 Vocalization Genes
Using a method that allows them to see which genes are working together and which are isolated from each other, scientists found that many more genes are involved in vocalization than previously thought. They are particularly interested in which genes are used to create new sounds.
They found that male finches, which learn courtship song about a month after hatching have an Area X. Females, which do not sing, do not have the same area.
These discoveries become even more interesting when comparing birds to humans. Human speech centers are also located in the basal ganglia, but like female birds, humans have no Area X. Despite that, many of the genes found in birds are also found in humans and other mammals.
FoxP2 And Reelin
Since human brains are too complicated to study at the cellular level, scientists believe understanding which genes are involved in bird song learning will ultimately lead to a greater understanding of human speech. Two genes of particular interest are FoxP2 and reelin.
The FoxP2 gene responds directly to singing; the more song produced, the lower the gene activity. It appears to be a control gene that turns other genes on and off. Reelin is important in vocal learning.
In humans, mutations in the FoxP2 gene have been known to cause speech disorders in families. The reelin gene has been linked to autism susceptibility. It appears that X not only marks the spot, it may hold clues to genetic-based human speech disorders.