The idea that people experience certain scents differently is not new. Scientists have known for a while that for some people cilantro tastes like soap and beets taste like dirt for reasons likely connected to smell. They’ve also known that only some people can detect the chemical that makes urine smell differently after someone has eaten asparagus, and that the scent of a compound in men’s sweat is different depending on one’s genetic code.
“Some people find androsterone very disgusting and intense and sweaty (me included),” wrote Leslie B. Vosshall a a neuroscientist at The Rockefeller University, who identified the genetic code behind the sweaty difference in 2007. “Others find it not too unpleasant and use adjectives like ‘chemical’ or ‘vanilla,’ yet others cannot smell it at all.”
What’s different about this study is that it attempted to identify the genetic underpinnings of a broader number of scent-detection differences. You have around 400 olfactory receptors at the top of your nasal cavity, and they activate differently depending on what you’re smelling. “Odors bind and turn on specific detectors, and this pattern of activation tells us if we’re smelling a flower, how strong we find it, whether we like it,” said Dr. Trimmer. “Small changes in the gene for the receptor can change its shape and how well the odor fits, thereby altering perception of the odor.”
As they looked for patterns in the genetic sequences and compared them to how the participants rated the scents, the scientists thought that androsterone would be an outlier in that differences can be traced to a single receptor. “But here we show that this phenomenon is not uncommon,” she said.
How it matters — beyond giving people a biology-based excuse to refuse to eat beets and buy overpriced whiskey — is that it helps demystify the olfactory system a bit further.
“Olfaction is the most important sense for the rest of the animal kingdom,” said Dr. Lomvardas. And though its essential role is less obvious when humans don’t have to sniff out their next meal, it still affects much more than just perfume preference and flavor experience. There is evidence that reduced sense of smell has psychological consequences, he said, and it may offer early clues of an oncoming neurodegenerative disorder such as Alzheimer’s disease.
Of course, genes are not the only determinant of scent. Rachel Herz, who studies the psychological science of smell at Brown University calls this new study “great and important” but points out that there are many other factors at play, including attention, past associations and expectations.
“There’s also an ability to create odor illusions and flip people’s perception of an odor,” she said. She’s done this by presenting people with a chemical combination and telling them that it’s vomit. She then presented the same chemical combination and told them it was Parmesan cheese. The participants refused to believe that the samples were the same, she said, as one was so clearly disgusting and the other was so clearly delicious.