The world’s noses agree – there’s one smell we prefer over all others

It is a scent sometimes maligned for being a safe and boring choice. But vanilla has now been crowned the world's favourite smell by a team of international experts.

Scientists from the University of Oxford and the Karolinska Institute in Stockholm presented 10 scents to 235 people from nine different cultures around the world.

The nine cultures included people from urban areas in America, Mexico and Thailand, as well as secluded farmers living in the South American mountains, hunter-gatherers in the south-east Asian rainforest and fishing communities on Central America’s Pacific coast.

Field scientists working in remote areas were recruited for the project to get scented vials to isolated individuals with little or no prior exposure to Western odours.

“Since these groups live in such disparate odiferous environments, like rainforest, coast, mountain and city, we capture many different types of ‘odour experiences’,” says Dr Artin Arshamian from the Karolinska Institute, the study author.

“We wanted to examine if people around the world have the same smell perception and like the same types of odour, or whether this is something that is culturally learned.

“Traditionally it has been seen as cultural, but we can show that culture has very little to do with it.”

They discovered that cultural connotations or affiliations had little impact on how much someone liked a smell, with the fragrance’s chemical structure eliciting a widely liked or disliked response, irrespective of where in the world they live, what language they speak and what they eat.

The 10 scents used in the trial were chosen deliberately to be representative of all the odours found in the world, as determined by a previous study that analysed almost 500 smelly molecules.

They included chemicals that smelled like sweaty feet, decaying fish, mushrooms, lavender and vanilla.

Participants of the study, which was published in the journal Current Biology, were simply asked to smell each chemical and rate how pleasant they found it compared with the other nine.

Vanilla, produced from orchid, came out as the most preferred smell, followed by a chemical that smells like peaches and a lavender-like scent.

At the other end of the scale, the most unpleasant smells were chemicals called isovaleric acid, diethyl disulfide and 2-isobutyl-3-methoxypyrazine, which smell like sweaty feet, decaying fish and overly ripe green peppers, respectively.

Overall, the trends were consistent for all 10 compounds in all nine locations.

“Cultures around the world rank different odours in a similar way no matter where they come from, but odour preferences have a personal – although not cultural – component,” says Dr Arshamian.

Smells may be linked to increased chance of survival

He speculates that people agree on what smells are more pleasant than others, irrespective of geography or lifestyle, because certain odours may be historically linked to an increased chance of survival.

For example, our olfactory sense may trigger disdain for a certain smell because it was associated with a toxic plant by our ancient ancestors. On the other hand, we may enjoy other smells because they were produced by other plants which were safe to eat.

“Now we know that there’s universal odour perception that is driven by molecular structure and that explains why we like or dislike a certain smell,” Dr Arshamian says.

“The next step is to study why this is so by linking this knowledge to what happens in the brain when we smell a particular odour.”