Everyone processes scents differently - some could easily sense them, others need them to be intense to smell them, and a few could not detect them at all. A new study led by a team of researchers from the Chinese Academy of Sciences in China suggests that humans' sense of smell is somewhat degrading over time.
The team discovered that a mutation in the scent receptor that is responsible for sensing body odor has made it difficult for humans to pick up the smell. Also, researchers claimed that scent receptors for perfume might also be waning in intensity.
Mutation in Scent Receptors Caused Decline in Humans' Sensitivity to Body Odor
Scent Receptors Involved in Perceiving Different Scents
It is almost impossible to ignore other people's body odor when in a tight space, such as on a commuter train. Scientists said that it is because of the scent receptors that detect body odor.
According to The Guardian, there are more than 400 scent receptors that detect different types of scents, but only a fraction of them are responsible for picking up the nasty stench from the body.
Dr. Joel Mainland, a co-author of the study from the University of Pennsylvania, said that they also discovered some previously uncovered scent receptors. It includes the receptors for detecting the chemical for freshly cut grass and a steroid hormone that smells urine.
Scent Receptors for Body Odor and Perfume Are Now Less Sensitive
Researchers of the new study, titled "From Musk to Body Odor: Decoding Olfaction Through Genetic Variation" published in PLOS Genetics, believe that the newer scent receptors for sweat and perfume are now less sensitive. That means the sense of smell of humans and primates are degrading over time, and that is because of the genes that code for these scent receptors.
According to MailOnline, the study involved screening the genomes of 1,000 Han Chinese people to identify the genetic variations that affect their perception of 10 different scents. Then they repeated the same study on a diverse population of 364 people from New York to confirm their results.
They were able to identify the scent receptors for the one that detects synthetic musk and the scent receptors for detecting body odor. Participants have different versions of the genes responsible for scent receptors that detect those scents, which affects how each of them perceives the scents.
Researchers wrote in their study that those with ancestral versions of the scent receptors, which are shared with non-human primates, tend to rate body odor and perfume as more intense. The findings support the hypothesis that humans' and primates' sensitivity to scents has degraded over time due to genetic mutations responsible for various scent receptors.
Furthermore, the findings also showed the three links between genes for scent receptors and specific odors that were tested on Caucasian participants. The authors suggest that the study's findings on East Asian participants showed that genetics played a critical role in the ability to detect odors regardless of their ethnic backgrounds.
Why Can Some People Not Smell?
The condition called anosmia is the partial or full loss of the sense of smell that can either be temporary or permanent. According to Yale Medicine, this could happen when mucus membranes in the nose are irritated or obstructed, like when the person has a severe cold or sinus infection.
There are also rare cases when some people are born with congenital anosmia due to an inherited genetic disorder or abnormal development of the olfactory system.
Treatment for anosmia could vary depending on the cause of the condition. However, when the cause of anosmia is not detected, the condition cannot be treated.
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