In our noses are about six million smell receptors and about four hundred different types. How these receptors are spread out varies according to each person, and because of this variance, to each his or her own sense of smell. Yes, we each have a unique smelling nose. Published in the Proceedings of the National Academy of Sciences (PNAS), Weizmann Institute researchers discovered how to identify an individual’s sense of smell, which they’re calling an “olfactory fingerprint.”

The importance of this study is that each one’s smell fingerprint may lead to many medical improvements from early diagnosis of degenerative brain disorders to a non-invasive test for matching donor organs.

The method to this madness is based on how similar or different two odors are from one another. In the first stage of the experiment, scientists asked the volunteers to rate 28 different smells according to 54 different descriptive words, like “lemony,” or “masculine.” Dr. Lavi Secundo led the study, along with Drs. Kobi Snitz and Kineret Weissler, all members of the lab of Prof. Noam Sobel of the Weizmann Institute’s Neurobiology Department. They developed a multidimensional mathematical formula that allows patients to identify how similar any two odors are to one another in the human sense of smell. This formula does not require the subjects to agree on the use and validity of any one given verbal descriptor; so the fingerprint is odor dependent but descriptor and language independent.

The next stage of the research suggested that our olfactory fingerprint may tie in with another system of ours in which we all differ – the immune system. They found, for example, that an immune antigen called HLA, today used to assess matches for organ donation, is correlated with certain olfactory fingerprints. This part of the study was conducted together with Drs. Ron Loewenthal, and Nancy Agmon-Levin, and Prof. Yehuda Shoenfeld, all of Sheba Medical Center.

So might this work for millions of patients? The researchers say that their figures prove that 28 odors alone could be used to “fingerprint” two million people, and that it would only take 34 odors to identify seven billion individuals on the planet.

But this smell fingerprinting could lead beyond identifying individuals, because it could be developed into methods for the early detection of diseases like Parkinson’s and Alzheimer‘s, and it could lead to non-invasive methods for screening donor matches.