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Scientists are flocking to the brains of songbirds to learn about human language and speech disorders. This ScienCentral News video has more.
Feathered Friends
Birds are pretty far away from humans on the evolutionary ladder. But scientists have found that songbirds have a gene that is important in human language learning.
"There is a connection between human language and bird vocal imitation at the genetic level," says Erich Jarvis, a neurobiologist at Duke University. "What we discovered is that songbirds and other birds that have the ability to imitate sounds contain a gene called FoxP2 that is known to be involved in human language. It's the first time we have a gene that we can study now in songbirds that we know is linked to language in humans."
The FoxP2 gene was found to be involved in human language several years ago. Its mutation produces an inherited language deficit called an oral apraxia. People with this deficit have an inability to pronounce words correctly, form them into sentences that are grammatically correct, and understand complex language.
"We decided to look for this gene in other species of animals who can actually imitate sounds like humans can do," explains Jarvis. "And this is a very rare trait. Only hummingbirds, parrots, and songbirds, as well as bats and dolphins, have this ability. So we studied birds, and what we found is that birds also have this same gene."
Jarvis and his team, including Constance Scharff at the Max Planck Institute for Molecular Genetics, compared the expression of the FoxP2 gene in birds that are considered "vocal learners," such as finches, song sparrows, canaries, parakeets, and hummingbirds, with its expression in birds that are "vocal nonlearners," such as ringdoves. They wanted to learn where and when the gene is expressed in the bird brain, and whether it was expressed more actively when the birds were singing. And they analyzed the structure of the bird version of the gene, and compared it to the human version.
Jarvis found that the FoxP2 gene was expressed in the same part of the brain in humans and songbirds— the basal ganglia— and that it was expressed at higher levels in the birds when they were learning songs. "The gene is made at high levels right before [the birds] are about to imitate sounds from adult tutors," says Jarvis. "And after they're finished imitating those sounds, the gene comes down to very low levels in the brain." This implies a cause-and-effect— when the gene switches on, the birds can learn their songs. There was no difference in the level of the gene in the non-vocal-learning birds.
Jarvis believes that understanding how the FoxP2 gene helps birds learn to sing could lead to help for people born with language difficulties. "We would like to find out if we could manipulate this gene in the bird brain, he says. "And if we can do that, then it leads to possibilities of us trying to manipulate it in humans at some time in the future and help these people who have language deficits."
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