April 4, 2013 | Vol. 116 -- No. 50

Of bird songs and human speech

Rock Doc

There are two features of this time of year that make my heart glad. One is the rapidly increasing length of the day. In September we lose daylight quickly, but in the spring we gain it all back just as rapidly. Although the same pattern is repeated each year (so you’d think I’d be used to it) I’m always somehow surprised and delighted when we get to this time of year and have early sunrises and spreading daylight in the evenings.

The other part of this time of year that gladdens my soul is the singing of birds. Starting as soon as it gets light, the birds go at it, vocalizing for their own purposes but entertaining all of us who listen for a minute before we rush off to work.

Recently scientists announced new findings regarding bird songs and what makes them possible in terms of fundamental neurobiology. Songbirds, it turns out, are interesting to study because when they hatch out of their eggs they don’t know the songs they will later sing as adults. That means they are a bit like us people when we are born. Like the birds, we have to learn to make sounds and speak like our parents; it’s not something we are born able to do.

It’s not that birds and people are highly similar in evolutionary terms and thus share this same basic trait of needing to learn how to vocalize like our kin. Indeed it’s been about 300 million years since birds and humans had a common evolutionary ancestor – that’s a long time even by geologic standards! At some point since that long ago split, both the animals that became birds and the primates that later led to us people independently acquired the ability to make complex tones and sounds.

Erich Jarvis of Duke University Medical Center is a neurobiologist who has “gone to the birds” in his quest to understand how it is some animals learn to speak the languages in which different species are immersed. He and his colleagues recently announced findings of their work. One of the take away messages of the research is that brains in quite different species have evolved over time in similar ways to produce highly useful features like songs and speech.

“I feel more comfortable that we can link structures in songbird brains to analogous structures in human brains due to convergent evolution,” Jarvis said to a reporter from ScienceNews.

Jarvis and company discovered some 80 genes that turn off and on in like manner in the brains of songbirds and people. The genes don’t behave that way in the brains of birds that don’t learn tunes from their parents.

The research could have some useful applications. It’s possible that combining it with the data that describes the entire genetic code of people could yield practical information about things like speech disorders.

Like the longer and longer days we’re enjoying, that would be something to sing about.

Dr. E. Kirsten Peters, a native of the rural Northwest, was trained as a geologist at Princeton and Harvard. This column is a service of the College of Agricultural, Human and Natural Resource Sciences at Washington State University.

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