A new study shows that the human sense of smell is far stronger than we previously believed
The human nose can distinguish more than one trillion different smells. To reach this conclusion, scientists had to conduct a long and complex study. Fortunately, dozens of volunteers agreed to participate in the research and helped make this scientific work possible.
For many years, the scientific community believed that the human nose could distinguish about 10,000 different smells. However, new research has shown that this number is actually much lower than reality. According to scientists’ calculations, the human olfactory system can distinguish approximately 100,000 times more, which means nearly one trillion different smells.
Neuroscientist Noam Sobel from the Weizmann Institute of Science in Rehovot, Israel, comments on this finding:
“We usually imagine humans as creatures whose strongest sense is vision. However, this research shows that the human sense of smell is also extremely developed and complex.”
It should be noted that Sobel was not one of the authors of the study, although he highly values the scientific importance of its results.
What does one trillion smells mean?
One trillion (1,000,000,000,000) is an extremely large number. To better understand this scale, imagine the following example: if every person living on Earth had 140 unique personal smells, the human nose would still be able to distinguish each of them.
In other words, the human olfactory system is far more delicate and sensitive than we once thought.
The sense of smell compared with sight and hearing
The study was led by Leslie Vosshall, a geneticist at Rockefeller University in New York. In an interview with Science News, she stated that the human sense of smell is not inferior to other senses.
According to her:
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The human eye can distinguish several million different colors.
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The human ear can detect approximately 340,000 different sound tones.
However, the range of smells that humans can distinguish may be even broader than these numbers.
The results of this study were published on March 21 in the journal “Science.”
How was the research conducted?
For the experiment, researchers selected 26 male and female volunteers. The participants underwent numerous smell recognition tests.
Each volunteer completed a total of 264 different smell tests.
During the tests, participants were presented with three vials:
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Two vials contained the same smell.
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The third vial contained a different smell.
The volunteers had to determine which smell was different from the other two.
How were the smells created?
In real life, smells usually arise from mixtures of different molecules. Therefore, during the experiment scientists also created new smells by combining different molecules.
The smells used in the study were prepared from different combinations of 128 chemical substances.
How do humans distinguish smells?
The results of the experiment revealed several interesting findings.
People:
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Can easily distinguish smells made of completely different molecules.
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Can also detect differences between smells where half of the molecules are the same.
However, as the similarity between smells increases, distinguishing them becomes much more difficult.
None of the participants in the study were able to distinguish between two smells that contained 90 percent identical molecules.
The potential of the human nose
According to scientists’ calculations, the average human nose can distinguish about one trillion different smells created by combinations of roughly 30 odor molecules.
However, people differ in their sensitivity to smell.
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Individuals with highly sensitive olfactory systems may distinguish far more smells.
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People with weaker smell sensitivity may distinguish around 80 million smells.
Limitations of the research
During the study, scientists used only 128 odor molecules. In reality, the number of odor molecules that exist in the world is much larger.
Co-author of the study Andreas Keller believes that for this reason, the number of one trillion may actually represent the minimum estimate of the human olfactory capacity.
The sense of smell in other living creatures
Noam Sobel notes that many animal species can also distinguish trillions of smells. However, large-scale scientific studies on animals in this field have not yet been conducted.
It is well known that dogs, rodents, and some other animals have a much stronger sense of smell than humans.
Conclusion
New scientific research shows that the human olfactory system is far more complex and powerful than we previously believed.
The ability to distinguish more than one trillion smells once again proves how advanced the human brain and nervous system are.
These findings open new opportunities for research in neurology, human sensory systems, and the study of the organs responsible for perception.