DNA blueprint of zebra finch gives human language clues

By Courtenay Rule 1 April 2010
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The first songbird to have its genome deciphered may offer new insight into how human children learn to speak.

A GLOBAL TEAM OF scientists has sequenced the genome of Australia’s native zebra finch, in a breakthrough that may provide new insight into the biological basis of how human children learn to speak.

“In studying other species’ genes, we can see things that are relevant to humans as well, but aren’t so easily highlighted in us,” says neurobiologist David Clayton from the University of Illinois, in Chicago, who is one of the project’s leaders.

A genome is the sum total of all of an organism’s DNA. To fully sequence this code, scientists must determine the order of the many millions of individual genetic ‘letters’ that the DNA is made of. These letters form into genes, which can be thought of as meaningful ‘words’ that together direct the way an organism develops and functions.

The project was a collaboration involving institutes from six countries (the US and UK, Germany, Sweden, Spain and Israel), who spent some four years unravelling and analysing the DNA of the finch, which has become the first songbird, and only the second bird ever (after the chicken), to have its complete DNA blueprint sequenced. The results are published today in several papers in the journal Nature.

Learning to sing

One unusual feature of the zebra finch is that, like humans, it communicates through vocalisations – songs — that are learned. Adult male finches sing to attract a mate. Baby finches babble all sorts of sounds, but as the young male finches grow, they gradually learn to sing by listening to and copying their father’s song. This is similar to the way human babies learn to speak by imitating their parents.

The zebra finch is a common laboratory species used worldwide for studying genetics and development. Now that the finch genome is known, David and his fellow researchers hope that by finding genes that have a link with learning to sing, we could find similar genes that control how human children learn and use language. This in turn could lead to improved treatments for speech disabilities related to autism and stroke.

The study also yielded valuable insights into how different genes within the finch’s brain are turned ‘on’ or ‘off’ as the bird interacts with others. These patterns of expressed genes vary according to the circumstances, such as whether the bird is hearing a familiar song or one it hasn’t heard before. According to David, this may point to how the brain stores memories and adapts to the world around it.

Social interaction similar to humans

Because finches live in large social groups but generally form monogamous pair bonds — very much like our own species — there may be parallels in the biological basis for this social organisation and behaviour.

“Through the zebra finch genome, we can see that social interactions are one of the most important things to any species,” David says. “There is actually a complex interplay between the genome and social interaction, which triggers the expression of genes and leads to changes in the structure of chromosomes. Not much is known yet about what this means and what the implications are for how intelligent organisms work. It’s a new mystery for us to try to explore and understand.”

Behavioural ecologist Simon Griffith of Sydney’s Macquarie University, who studies zebra finches in the wild, agrees that this project is of great significance. What’s more, he points out, it’s something all Australians should celebrate.

“It’s very neat that we’ve got this amazing species, native to Australia, that’s gone around the world [to be studied],” he says. “It’s one of the most important organisms in science, and I think that in Australia we should be proud that we’ve got this little bird.”