Who Passes The Smell Test

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Who Passes the Smell Test?

An animal schnoz is obviously superior to our own mediocre noses, right?

Not so fast. Matthias Laska, a biologist at Linköping University in Sweden, has been comparing senses of smell across species — including humans — for more than two decades. “The more data I collected on different species over the years, the more interesting the picture became,” Laska says.

But sizing up how sensitive the snout of, say, a seal is compared with a bat or human isn’t straightforward. People can tell you when a certain scent is no longer detectable. But each animal has to learn to associate a particular odor with a reward and then do something, like press a button, to let researchers know when they smell it.

The odors compared between species also have to be the same. That sounds obvious, but while humans have sniffed around 3,300 different scents for science — out of the trillions possible — the highest number for animals is 81, by spider monkeys. Laska only found solid enough data to compare humans with 17 species, all mammals.

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However, human noses held their own. Humans tested as generally more sensitive sniffers than monkeys and rats on a limited range of odors. In fact, humans detected certain scents at lower concentrations than the notoriously top-notch nostrils of mice and pigs.

Humans even beat the indomitable  dog for at least a handful of scents. These include aromas produced by plants, a logical evolutionary advantage for our ancestors seeking fruits. The majority of the odors in which dogs bested us were the fatty acids, compounds associated with their own meaty prey. “Odors that are not relevant for you, you are usually not good at [smelling],” Laska says.

Bottom line: Humans, Laska says, “are not as hopeless as the classical wisdom will tell us, and dogs are not the super nose of the universe for everything.” — Ashley Braun


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