Air Date: Week of December 14, 2001

Living on Earth’s Maggie Villiger reports on lefties and righties in the crow world.

Transcript

CURWOOD: Just ahead, a trip through Alaska's Copper River Delta. Nothing much has changed there for the last 10,000 years except the people who visit this magnificent ecosystem. First, this page from the Animal Notebook from Maggie Villiger.

[THEME MUSIC]

VILLIGER: When you throw a ball, use a fork, or grab a pencil, chances are you use your right hand. Scientists think this is because we developed language. Language ability usually resides in the left hemisphere of the brain. As a consequence, the left half of our brains are beefed up, and one of the functions it controls is motor ability on the right side of the body. That's why 90 percent of us are right-handed.

Now scientists report that crows may have this same kind of handedness in their actions, even though they don't have hands or language. Crows in New Caledonia make a variety of tools to help them pick and probe for food in the treetops. They craft one tool by cutting and ripping a long, narrow triangle from a leaf. Researchers noticed that the birds chose to rip the left side of the leaf twice as often as they rip the right. There's no obvious advantage to a left or right-sided tool, since once they're made, the tools look exactly the same.

So, why do the majority of crows make their tools this way? Just as the left hemisphere in humans is responsible for language skills, researchers think in crows the left hemisphere holds the blueprint for these complex tools. And when crows are working on the left side of the leaf, it's their right eye, the one that's connected to that strong left hemisphere of the brain, that's looking at their handiwork. That's this week's Animal Note. I'm Maggie Villiger.

CURWOOD: And you're listening to Living on Earth.