Odorama: Smelling in stereo

Science & Technology

November 07, 1999|By San Francisco Examiner

"The nose knows," goes the old saying. But does it?

In a breath-taking discovery, Stanford University researchers are reporting that your left and right nostrils perceive smells slightly differently.

The difference is probably too subtle for you to notice most of the time. But it's significant enough to be detected in careful lab experiments, researchers Noam Sobel and John Gabrieli reported this past week in the science journal Nature.

For decades, scientists have known that the human brain allocates different responsibilities to the left and right halves of the brain. Apparently the nose does the same thing, although for different reasons.

This nasal division of labor makes sense in evolutionary terms, Gabrieli says. By making one nostril especially sensitive to certain smells and the other sensitive to others, the nose can sense a broader range of smells.

"It's like 'two heads are better than one,' " Gabrieli says.

The differences, the scientists say, are caused by variations in airflow through the nostrils. Curiously, a given nostril's ability to smell certain odors varies over time, and occasionally shifts to the other nostril --like spouses who occasionally swap responsibilities, such as watching the kids, washing the dishes or taking out the trash.

"What's mysterious," Gabrieli says, "is why it goes back and forth."

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