Beyond scents: what your nose knows

Maria Isabel Garcia
Beyond scents: what your nose knows
[Science Solitaire] The idea of the human 'noseprint'

Lately, I have been intrigued by the idea of a smell museum. It is a well-documented fact that smells occupy a deep imprint in our psyche that when there is a scent that accompanied an incident in your life, that same scent could most likely summon that memory again. So imagine the invisible vastness of the dimensions you could sniff in a smell museum.

But aside from about the trillion of scents that we can detect, there is something else that would make the smell museum a lot more fascinating.

A recent study had researchers devise a test where 89 participants identified 28 odors using 54 descriptors and indeed they found that from their responses, each individual could be identified. This made the case for the uniqueness of the human “noseprint.” But would this kind of “nose print” hold across a lifetime like fingerprints do? The researchers wanted to show more than the uniqueness of each nose. For this, they wanted to link it with our DNA, which is of course a distinct mark in each of us.

They had a good starting point – our 400 olfactory receptors – those proteins in our cells that respond to “messages” from our genes to express a function. They had a good idea this will work since it works for our eyes. Tests for color blindness indicate genes code for proteins in the retina called opsins – those that mediate the light that your eye receives into something that the eye could process. So they figured that smell receptors would also be strongly linked to our genome.

The researchers homed in on the already known link between the way we smell and a slew of proteins in our cells that have long been established to have been coded by a family of genes. This special bunch of proteins found in most vertebrates, named unattractively as the major histocompatibility complex or MHC, is largely responsible for an organism’s immunological functions. Our human version of that is called HLA (human leukocyte antigen). It became famous to the public in experiments that proved that women can smell their way to their genetically compatible mates.  

“Genetic compatibility” would mean that the more different two genetic make-ups were the better it is for their offspring since any “errors” in one would most likely not be expressed by the presence of the same ‘error” in the other. The study found that women were attracted to those with MHCs different from their own.

The study revealed that indeed olfactory prints matched HLAs significantly, proving that “noseprints” could be reliable identifiers, not just of how we smell but of our genetic make-up at large.

Lately, I have been hearing the word “optics” a lot in marketing circles. After being confused enough, I asked and it turns out, it refers to “perception.” I think this is evidence of the visual tyranny that sighted people yield – collapsing “perception” into only what light shines on to.  There are other senses – some even more powerful than sight in revealing other things, just like the nose on this latest study.

Maybe I will place my fanciful museum of smells – all invisible whiffs – next to a gallery of visual art. Maybe it will be a lesson not for competing senses but a deepening of each one for a more biting sense of being alive. –

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