In the nose of each person there are about six million smell receptors divided into about four hundred different types. Naturally, the distribution of these types of receptors differs from person to person, which has led to the assumption that each person has a unique sense of smell. In a study recently published in the scientific journal "Records of the National Academy of Sciences of the United States of America" (PNAS), scientists from the Weizmann Institute of Science reported that they had developed a method for the precise characterization of the perception of smell, which constitutes a kind of "personal fingerprint", which enables the identification of each person, and which teaches on a variety of properties beyond the sense of smell. For example, the perceptual "fingerprint" of the sense of smell could perhaps, in the future, be used as a basis for early diagnosis of degenerative brain diseases, and perhaps also for the adjustment required for organ and bone marrow donation.
The perceptual fingerprint developed by the institute's scientists is based on the evaluation of the similarities and differences between smells. Each of the 89 participants of the first experiment rated 28 smells using 54 verbal descriptors such as how "lemon", "masculine", "pleasant", etc. the smell was. The scientists, led by Dr. Lavi Secundo, and with the participation of Dr. Kobi Snitz, and Kinneret Whistler from Prof. Noam Sobel's laboratory, developed a mathematical method that allows one to calculate - according to the ratings of the subjects - the degree of similarity and difference between each pair of smells as they are perceived by the senses The smell of every person. The strength of the method stems from its lack of dependence on the words used to describe the smells, and the fact that it does not require agreement between people. That is, the method measures the perceptual similarity and difference between smells - regardless of language.
The scientists used 28 smells, and thus could calculate for each participant the degree of similarity or difference for 378 pairs of smells. This is how the scientists got a kind of "fingerprint" with 378 dimensions for each person. The scientists found that each participant in the experiment had, indeed, a unique "fingerprint" of smell perception. Based on the variation in the sample, the scientists calculated and found that with 28 smells it is possible to characterize a "personal fingerprint" for two million people, and with 34 smells it is possible to characterize such a fingerprint for each of the seven billion inhabitants of the earth.
Later, a correlation was found between the "fingerprint of the sense of smell" and other features, including the presence of an immune antigen called HLA, which is used as a marker for matching in organ donation. This part of the research was carried out in collaboration with Dr. Ron Leventhal, Dr. Nancy Agmon-Levin and Prof. Yehuda Schoenfeld from the Sheba Sheba Medical Center.
"In order to measure the similarity between the various subjects," says Dr. Secundo, "we created a unique Euclidean mathematical space, into which we put the data of the subjects - and then measure, in units that we developed especially for this purpose, the distance between them that expresses the degree of similarity or difference" . The degree of similarity (i.e. the fingerprint of the sense of smell) may form a basis for the future development of methods for the early diagnosis of degenerative brain diseases such as Parkinson's and Alzheimer's, and possibly also in the adjustment required for organ and bone marrow donation.
More on the subject on the science website
One response
Satisfying work, but I have a question.
The nature of smell perception does not depend only on the characteristics of the receptors in the nose, but also on the brain's interpretation of that smell, which is based on the history of that person's experiences.
All the more so when the smell is characterized by concepts that are quite abstract such as "masculine" and "lemon". Concepts that in themselves have a great difference in meaning from person to person.
For example:
To me, the smell of BRUTE deodorant has always smelled masculine, because when I was a little boy my father used it.
another example:
The smell of jasmine extract is unpleasant to me and reminds me of toilets, because in our toilets there was always a jasmine-scented air freshener, and the smell of jasmine is associated with the smell that makes it necessary to use an air freshener.
From here I make three apparent claims against the study:
1) The perception of smell does not derive only from a biological structure, but also from brain processing - which may weaken the connection between the smell imprint and other biological properties.
2) The brain processing of the perception of smell can change during life - so that the unique fingerprint will change.
3) The concepts presented in the article for characterizing smells can be interpreted broadly. (The word "pleasant", on the other hand, cannot be given a broad interpretation, in my opinion. It is possible that a certain smell is pleasant for one person and not pleasant for another, but the experience of pleasant is very similar, relatively speaking, in my opinion, for all humans.)