QotW: why do our senses of smell differ?

Her in the UK fields of rapeseed run parallel to the roads, can you smell them?
31 May 2022





Otis Kingsman looks into this smelly conundrum sent in by listener Tim, 'why can't my partner smell certain strong odours? When in the countryside she can smell manure, but is immune to smelling certain potent flowers and herbs.'


When traveling to The Naked Scientist's office, I end up passing through a series of fields. And let me tell you, I wish I could block out some of those smells. Here to explain the situation of your partner's ability to smell is professor of neurobiology, Sandeep Robert Datta from Harvard Medical School. But before that, we should first understand how we even smell in the first place...

Sandeep - Smells are actually detected in your nose by specialised cells called 'olfactory sensory neurons'. These neurons detect smells because each expresses a specialised odour detector called an odour receptor. Your genome actually encodes about 400 of these different receptors and each one of these receptors is specialised to interact with a different set of odorants. You can think of each odour receptor as like a lock, and an odour like a key. Odours float into your nose and when they find the matching receptor, when the key finds the lock, the receptor gets turned on and the neuron gets activated.

Otis - These neurons send signals to our brain telling us what the scent is. However, individual receptors come in unique variants, which lead to everyone having a different selection of receptors in our nose.

Sandeep - It turns out, for at least some smells, your ability to detect the smell and your perception of smells can depend on the specific receptor genes you've inherited from your parents. For example, there are some people who love the smell of male underarm sweat, while to others it's disgusting. The reason different people have different perceptions of that particular odour is because they've inherited different versions of the gene that encodes the receptor for male underarm, sweat.

Otis - And here I was thinking that deodorant was essential to make armpits smell better. So genes are a likely cause of why we have different smell receptors, and therefore while your partner may not be able to smell certain scents. It doesn't matter how strong the smell is, if we don't have the right receptors our brains won't detect for smell.

Sandeep - That isn't to say that genes are everything. Smell perception also crucially depends on our experience of smells both recently and across the lifetime. But genes are the most likely explanation for what's going on between you and your partner, assuming that you and your partner both share a cultural background and have shared most of your recent olfactory experiences.

Otis - Thank you to professor Sandeep Robert Datta for helping us sniff out that answer. Next week, we'll be looking at this communication conundrum from listener Mike.

Mike - Does email and texting affect our brain's cognitive functions?


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