Study Shows How Humans, Other Primates Developed a Less Sensitive Nose Over Time

Variations in the genes for the newly found musk and underarm odor scent receptors add to a growing body of evidence that humans' sense of smell is increasingly deteriorating.

These findings are reported in recent research published Feb. 3 in the journal PLOS Genetics by Sijia Wang of the Chinese Academy of Sciences and Joel Mainland of the Monell Chemical Senses Center.

Smells affect everyone differently; the same fragrance might be pleasant, overpowering, or even unnoticeable to other noses. Scientists can use these variances in scent perception in combination with a person's genetics to figure out what function different scent receptors play.

Researchers searched the genomes of 1,000 Han Chinese adults for genetic differences connected to how they perceived ten distinct odors in a new study.

They then replicated the experiment with six other scents in a 364-person ethnically diverse sample to corroborate their findings. The researchers discovered two novel receptors, one for a synthetic musk used in perfumes and the other for a chemical found in human underarm odor.

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Odor Receptors

Different variants of the musk and underarm odor receptor genes were found in the participants, and these genetic differences influenced how they experienced the odors. Based on earlier findings, the researchers discovered that persons who had the ancestral variants of the smell receptors (the kind shared with other non-human primates) assess the matching odor as more powerful.

These findings corroborate the theory that changes in the set of genes that code for our smell receptors have caused the sensitivity of humans and other animals' sense of smell to deteriorate through time.

Comparing Genetic Research

(Photo : Nicholas Githiri)

Genetic research also discovered three previously unknown correlations between smell receptors and specific scents genes. The subjects in these earlier investigations mainly were Caucasians. The latest findings from East Asian and varied communities imply that the genetics underpinning the capacity to perceive scents is consistent across cultures.

"Genome-wide scans discovered unique genetic variations related with odor perception, giving support for the concept that the primate olfactory receptor repertoire has evolved over time," the scientists conclude.

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