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Human noses know more than 1 trillion odors

Smell played an underappreciated role in evolution

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2:00pm, March 20, 2014

SMELL DETECTORS  A researcher whiffs a scent-containing vial used in experiments indicating that people can identify at least 1 trillion different odors.

Respect the nose. Humans use it to tell apart an average of more than 1 trillion odors, a new study finds.

That estimate of smell’s reach vastly exceeds the roughly several million colors and 340,000 tones a typical person can distinguish, reports a team led by geneticist Leslie Vosshall of Rockefeller University in New York City. A decades-old claim that humans discriminate only about 10,000 odors had not been systematically tested until now, the scientists say in the March 21 Science.

Most odor researchers already thought that people could whiff far more than 10,000 scents. Previous investigations found that humans have 400 genes that code for odor-sensing molecules. That’s a sign that smell discrimination played a significant role in human evolution, says Rockefeller geneticist and study coauthor Andreas Keller.

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