like the smell of vanilla? so does the rest of the world
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researchers likened the brain's process of smelling to experiencing a symphony or painting. getty
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if you like the smell of vanilla, you’re not alone — in fact, you have something in common with people all around the world.
a new study from the karolinska institute in solna, sweden, published in the journal current biology, looked at why people like the smells they like. they were interested in finding out whether cultural norms dictated which scents people liked. what they found though, was that culture actually played a fairly small role: globally, most people liked the same smells, and personal preference turned out to be a much more important factor than cultural background.
“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,” dr. artin arshamian, one of the study’s co-authors, told the university’s news outlet.
the study included a total of 235 people from various parts of north and south america (city dwellers in the u.s. and mexico, indigenous groups in mexico, ecuador and peru) and east asia (city dwellers in thailand as well as small ethnic groups in various parts of thailand and malaysia). the non-city dwellers who were part of the study lived in very different climates — some mountainous, some in forests, others on the coast or near bodies of water — and in different kinds of temperatures. overall, the study’s respondents lived in “disparate odiferous environments,” arshamian said — they encountered very different kinds of smells in their everyday lives.
vanilla, fruits are universally popular smells
all the respondents were asked to rank specific smells on a scale from pleasant to unpleasant. they smelled each one for two to three seconds, and waited at least 20 seconds between each. researchers found that variation between answers was more explained by personal preference (54 per cent of the variance between answers) and the smell’s molecular structure (41 per cent) than by a person’s culture.
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the scent of vanilla was most popular, foot odour not so much
of the scents that were tested, vanilla was the most popular. it was followed by ethyl butyrate, a chemical compound that smells like peaches or pineapple. the least pleasant, meanwhile, was isovaleric acid, a compound that smells like foot odour and pungent cheese.
the universal quality of good vs. bad smells could have an evolutionary explanation, arshamian theorized: there are obviously some notable exceptions, but overall it was likely useful for humans to learn that many things that smell good provide nutrition, while things that smell bad are often bad for us to consume.
“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,” he said. “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.”
our brains process smells ‘like a painting and a symphony’
the study comes just days after another study on smell was published in the journal cell reports. that one, out of the university of rochester’s school of medicine and dentistry, looked at how our brains process smells. the study likened the brain’s processing of odour to both a painting and a symphony: there’s both a snapshot function and a function that tracks ever-evolving patterns.
researchers built a model of the early olfactory system, which the brain relies on to smell, and used a computer program to simulate what happens when we smell something. they found that a crucial part of what happens is due to centrifugal fibres, which carry our impulses from the central nervous system to the brain’s sensory areas. these fibres move around, trying different strategies to communicate to our brains what it is we’re smelling.
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in one form of the fibres, cells in our piriform cortex (the part of the brain that relates to smell) take a “snapshot” of one specific moment in time. in another form, the cells classified the smell by relying on the patterns that our brain activity performs across time.
“these processes suggest the brain has multiple responses to representing a smell,” the school’s news outlet explains. “in one strategy, the brain uses a snapshot, like a painting or a photograph, at a given moment to capture the essential features of the odour. in the other strategy, the brain keeps track of the evolving patterns. it is attuned to which cells turn on and off and when — like a symphony.”
exactly how and why these changes occur isn’t totally clear, but it’s likely scientists will continue to sniff out more research on how our brains process different scents.
maija kappler is a reporter and editor at healthing. you can reach her at mkappler@postmedia.com
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