A new study suggests that every individual’s sense of smell differs slightly from other people, based on their genetic makeup.
According to Science News, a newly devised test can tell individuals apart solely based on their sense of smell, meaning a person’s perception of odor is unique to him or her. The findings were published in the Proceedings of the National Academy of Sciences and released on June 22. Neuroscientist Noam Sobel of the Weizmann Institute of Science in Rehovot, Israel, led a team of researchers to the findings.
“Each person expresses a potentially unique subset of ∼400 different olfactory receptor subtypes,” says the study. “Given that the receptors we express partially determine the odors we smell, it follows that each person may have a unique nose.”
While every person obviously perceives odors similarly, there are slight variations in how they perceive smells because of the genes they inherited, and that variation may not be quite as slight as you’d expect. The study claims that there is an approximate 30 percent difference between any two people’s sense of smell. This means one individual’s perception of the scent of chocolate could be 30 percent different than someone else’s. Sobel and his team are the first to develop a test to distinguish these subtle sensory differences in the olfactory receptors.
The scent test works to detect the “olfactory fingerprint” of each person’s sense of smell. Test subjects smell 28 different odors and rank how strongly they matched a list of 54 descriptive words. The adjectives include words like “pleasant” or “nutty.” Based on their descriptions of the scents, researchers were able to map an “olfactory fingerprint” for each test subject and could therefore distinguish between individuals solely on their sense of smell. Impressively, researchers could identify each person by using only seven odors and 11 descriptive words by the end of the study.
Prof. Noam Sobel
Despite the amazing singularity of every person’s olfactory receptors, Sobel believes that humans’ sense of smell is undervalued in modern society, and many humans are not good at detecting smells. After we began to build civilizations, humans no longer needed to sniff out predators and meals, and the sense of smell quickly became less useful.
“Given a visual picture of an orange, people know what it is immediately,” said Sobel. “But we have shown in our labs that when the only cue is an odor, people are not very good at identifying what it is.”
While modern humans rarely use their sense of smell for any practical purposes, Sobel claims it still determines how individuals choose a sexual or romantic partner. Researchers found that test subjects with similar olfactory fingerprints also shared similar genes in their immune system proteins. These affect body odor and pheromones, which play a part sexual attraction. This suggests that people with similar senses of smell might actually smell alike to other people, according to another neuroscientist and study author Lavi Secundo.
However, the genetic makeup of the olfactory receptors can change over time, according to the study. This means that a human’s sense of smell can also differ from year to year as well as from person to person.
“Extrapolating from this data, we determined that using 34 odors and 35 descriptors we could individually identify each of the 7 billion people on earth. Olfactory perception, however, fluctuates over time, calling into question our proposed perceptual readout of presumably stable genetic makeup.”
Sobel provided a list of potential practical applications for the olfactory fingerprint test, including using the distinct fingerprint of individuals to diagnose diseases that affect the sense of smell, such as Parkinson’s disease. The test could even be used for security purposes, since unique olfactory fingerprints would be virtually impossible to copy or steal.
