Can You Smell That? Scientists Discover Genetic Underpinnings of Scent Sensing

When we sniff an apple or a rose, it smells appealing. Yet the scent that you're smelling may be different from the one someone else senses. Now, scientists have tracked down the genetic dissimilarities that underpin the differences in smell sensitivity and perception in individuals.

In order to examine these genetic underpinnings, the researchers tested nearly 200 people for their sensitivity for ten different chemical compounds that are commonly found in foods. Then they searched through these individuals' genomes for areas of the DNA that differed between those who could smell a given compound and those who couldn't. Known as genome-wide association, this method is often used to identify genetic differences.

It turns out that for four of the ten odors, there was a genetic association. This seemed to indicate that genetic make-up determines whether or not a person can smell these compounds, which included malt, apple, blue cheese and β-ionone, which smells floral to some people and is abundant in violets.

The scientists weren't done yet, though. They also compared the differences in sensitivities between human populations in different parts of the world. Surprisingly, though, they found no sign of regional differentiation; a person in Asia is just as likely to be able to smell one of the compounds as a person in Europe, for example. In addition, the ability to smell one compound doesn't predict the ability to smell the other.

"We were surprised how many odors have genes associated with them. If this extends to other odors, then we might expect everyone to have their own unique set of smells that they are sensitive to," said Jeremy McRae, one of the researchers, in a news release. "These smells are found in foods and drinks that people encounter every day, such as tomatoes and apples. This might mean that when people sit down to eat a meal, they each experience it in their own personalized way."

The findings could have implications for the development of future products. If a population is less likely to sense a smell, then that particular scent probably shouldn't be used to attract customers. In theory, companies could design foods that better target people based on their sensitivity.

The findings are published in two different papers in Current Biology. They can be found here and here.