How your nose decides who you love

A scent can suddenly remind us of something that happened many years ago. Which aromas remind you of past events?

I grew up in the town of Eutin in the German federal state of Schleswig-Holstein. There were piles of old newspapers in the attic of my parents’ house, some of which dated back to before the Second World War. The smell of yellowed newsprint takes me back to my childhood in an instant. I then feel the slight sense of eerieness and adventure again that I got when exploring our attic.

Why are memories and smells often so strongly linked?

Smell is our oldest sense – in evolutionary terms it developed before sight or hearing, and is located right next to emotional memory in the brain. That means odour perceptions can instantly evoke past emotions. Sensory stimuli that we take in through our eyes or ears go through a more complex process in the brain and have to pass through a kind of control room before reaching our emotional memory.

When two people have an intense dislike for one another, in German it’s sometimes said they can't stand the smell of one other. Is there any truth in that?

Whether you take a shine or an instant dislike to someone has much to do with their smell. Studies have revealed that people with similar body odours are more likely to strike up a friendship. But whether someone perceives fragrances in a similar way to you is a key factor too.

Can you explain that in more detail?

A rose doesn’t smell exactly the same to me as it does to you. Everyone perceives the scent of roses slightly differently. That’s because there are many different types of olfactory sense cells. If I have similar sensory cells in my nasal mucosa to someone else, I perceive scents in a similar way. This common ground is an important factor that fosters the development of friendships. It’s sometimes said two people have the same gut feeling, but what they actually share is the same sense of smell.

Do these similarities also determine whether or not we fall in love with someone?

Yes, this plays a key role when choosing a partner. You might even say that you love through the nose. However, falling in love with someone depends on many other perceptions too. A person’s appearance, the sound of their voice and overall personality are very important as well.

As scent signals play such a vital part in living together, an expensive perfume should actually work wonders. Can you make yourself popular and desirable?

Wearing a perfume you love will make you feel more attractive and may also boost your self-confidence. This can be advantageous in contact with other people. However, there’s no guarantee the other person will also like this particular scent. As I mentioned, people often perceive the same scent in very different ways. You should never spray too much perfume on anyway.

Doesn’t a fragrance’s effect increase when it’s particularly intense?

While the effect does increase, it can suddenly have the opposite impact. If a fragrance is too strong, it’s often perceived as being unpleasant. A very intense smell sends a signal to the body that something unfamiliar has entered everyday life, i.e. that something is wrong. That can be irritating and even alarming. That’s not really the effect you want perfume to have.

It’s often said you can smell fear. Is it actually true that you can perceive other people’s feelings through the sense of smell?

Yes, everyone constantly sends out scent signals that are closely related to their emotions. That means you smell differently depending on how you feel. The smell of cold sweat triggers a very strong reaction in the other person. It’s subconsciously perceived as a warning of danger - your muscles tense up, your senses sharpen and you involuntarily adopt a more cautious and suspicious approach.

Can you actually smell if someone is ill?

Yes, that’s true – the Swedish psychologist Mats Olsson proved it in an experiment where he triggered a tiny infection in individual students using a small amount of bacteria. The body temperature of these students rose by 1°C for a few hours. They didn’t even notice it themselves. Other students then sniffed the test participants’ T-shirts and found the odour unpleasant.

All this shows our nose is vitally important – it warns us of illnesses, for instance. Can we train our sense of smell so that it guides us through life in an even better way?

Yes, that’s possible. This can be done by smelling something two or three times a day with a scent that is completely unfamiliar to you – for example, an exotic spice mixture or dried flowers from a faraway country. This causes new nerve cells to form in what’s called the olfactory brain after just six weeks. This part of the brain has a remarkable ability to develop: a simple exercise is enough to sharpen our sense of smell.