Scent Secrets Unlocked, Artificial Noses Ahead?

Brian Handwerk
for National Geographic News
February 26, 2009

Scientists are decoding the way our noses recognize scents, laying the groundwork for a future of cancer-sniffing artificial noses and personalized perfumes.

In a recent experiment, researchers tested hundreds of receptor gene types found in human and mouse noses.

By inundating the receptors with odors, researchers were able to figure out which receptors respond to which odor molecules and translate the smells into brain signals.

Unlocking this interface would show how the brain recognizes and reacts to different smells.

"We used many different types of [odorus] chemicals, from strawberries to garlic, and these chemicals have specific structure. [We asked] what kinds of receptors are activated by each?" said study co-author Harumi Saito of Duke University.

"Only three receptor types facilitate all of color vision," said geneticist Joel Mainland of the Duke University Medical Center, whose findings will appear in tomorrow's issue of the journal Science. "For human smell you have 400 [receptors], so it becomes a very complex system to decode."

Avery Gilbert, author of What the Nose Knows: The Science of Scent in Everyday Life, added that "the big problem is lining up which odor molecules go with which receptors. It's as if you have a pile of locks and a pile of keys and you've got to find out which key goes to each lock."

Personalized Perfumes, Cancer-Sniffing "Noses"

Knowing how different receptors recognize odors could help produce artificial noses able to sniff out scents from cancer to bombs.

Gilbert most looks forward to a day when such work could allow us to explain why people perceive odors differently.

"There may be some people who think a smell has a certain spicy quality while others don't," he said. "Perhaps we could say it's because some have extra receptors while others don't."

That kind of information would be a boon for people who trade in smell for a living.

"You could do something like the [computer] monitor has done for vision, where you can mix red, green, and blue and make any color you want in a image," Duke's Mainland said.

"We can't do that with smell because we don't know how they mix together, but this is a first step in developing that kind of thing," he said.

Gilbert added: "Since the Renaissance, commercial perfumery has always been an empirical game. You try a formula and put it on the shelf to see if anybody buys it, but you never know.

"With this you could do a quick genetic test and predict which kinds of perfumes or wine or foods people will or will not like.

"That's a ways off, but that's where this path leads."

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