From fragrant to popcorn: US scientists identify 10 categories for smells


Forget the unique aroma of fresh coffee, wild lavender or cut grass, according to US scientists there are just 10 basic smells.

In claims that would confound French perfumers and will prove controversial, a new study has reduced the thousands of odours humans can detect to a handful of categories.

According to Professors Jason Castro, of Bates College, and Chakra Chennubhotla, from the University of Pittsburgh, some 144 smells they tested could be grouped into 10 categories - including “fragrant, popcorn” and “chemical”.

The scientists told the PLoS One journal that the new categories allowed people to build smells and could lead to the ability to predict a smell based on its chemical structure.

Working with a 1985 list of odour “character profiles”, researchers applied mathematical methods to simplify the olfactory information.

They described it as similar to compressing digital audio or image files. “You have these 10 basic categories because they reflect important attributes about the world - danger, food and so on,” Prof Castro said. “If you know these basic categories, then you can start to think about building smells.”

He added: “It's an open question how many fundamental types of odour qualities there are. This is in striking contrast to olfaction's 'sister sense', taste, where we know that five basic qualities seem to organise sensations.”

He added that the theory would need to be tested on more complex aromas - such as perfumes - and that natural scents were likely to be a “complex blend” of the 10 categories.

The science of smelling has long confounded experts with many claiming it still remains a mystery. It was only in 2004 that it was discovered how the brain recognises and remembers thousands of different odours thanks to a large gene family that controls specialised protein receptors in the nose.

Prof Richard Axel, of Columbia University, and Prof Linda Buck, of Fred Hutchinson Cancer Research Center in Seattle, were awarded the Nobel Prize for their discovery.

The categories

1 Fragrant

2 Woody/resinous

3 Fruity (non-citrus)

4 Chemical

5 Minty/peppermint

6 Sweet

7 Popcorn

8 Lemon

9 Pungent

10 Decayed

Start your day with The Independent, sign up for daily news emails
ebooksA special investigation by Andy McSmith
  • Get to the point
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
Independent Dating

By clicking 'Search' you
are agreeing to our
Terms of Use.

iJobs Job Widget
iJobs General

Recruitment Genius: Project Implementation Executive

£18000 - £23000 per annum: Recruitment Genius: They work with major vehicle ma...

Recruitment Genius: Chiropractic Assistant

£16500 per annum: Recruitment Genius: A Chiropractic Assistant is needed in a ...

Recruitment Genius: Digital Account Executive - Midlands

£18000 - £26000 per annum: Recruitment Genius: They work with major vehicle ma...

Recruitment Genius: Web Developer

£28000 - £30000 per annum: Recruitment Genius: This company provides coaching ...

Day In a Page

NHS struggling to monitor the safety and efficacy of its services outsourced to private providers

Who's monitoring the outsourced NHS services?

A report finds that private firms are not being properly assessed for their quality of care
Zac Goldsmith: 'I'll trigger a by-election over Heathrow'

Zac Goldsmith: 'I'll trigger a by-election over Heathrow'

The Tory MP said he did not want to stand again unless his party's manifesto ruled out a third runway. But he's doing so. Watch this space
How do Greek voters feel about Syriza's backtracking on its anti-austerity pledge?

How do Greeks feel about Syriza?

Five voters from different backgrounds tell us what they expect from Syriza's charismatic leader Alexis Tsipras
From Iraq to Libya and Syria: The wars that come back to haunt us

The wars that come back to haunt us

David Cameron should not escape blame for his role in conflicts that are still raging, argues Patrick Cockburn
Sam Baker and Lauren Laverne: Too busy to surf? Head to The Pool

Too busy to surf? Head to The Pool

A new website is trying to declutter the internet to help busy women. Holly Williams meets the founders
Heston Blumenthal to cook up a spice odyssey for British astronaut manning the International Space Station

UK's Major Tum to blast off on a spice odyssey

Nothing but the best for British astronaut as chef Heston Blumenthal cooks up his rations
John Harrison's 'longitude' clock sets new record - 300 years on

‘Longitude’ clock sets new record - 300 years on

Greenwich horologists celebrate as it keeps to within a second of real time over a 100-day test
Fears in the US of being outgunned in the vital propaganda wars by Russia, China - and even Isis - have prompted a rethink on overseas broadcasters

Let the propaganda wars begin - again

'Accurate, objective, comprehensive': that was Voice of America's creed, but now its masters want it to promote US policy, reports Rupert Cornwell
Why Japan's incredible long-distance runners will never win the London Marathon

Japan's incredible long-distance runners

Every year, Japanese long-distance runners post some of the world's fastest times – yet, come next weekend, not a single elite competitor from the country will be at the London Marathon
Why does Tom Drury remain the greatest writer you've never heard of?

Tom Drury: The quiet American

His debut was considered one of the finest novels of the past 50 years, and he is every bit the equal of his contemporaries, Jonathan Franzen, Dave Eggers and David Foster Wallace
You should judge a person by how they peel a potato

You should judge a person by how they peel a potato

Dave Hax's domestic tips are reminiscent of George Orwell's tea routine. The world might need revolution, but we like to sweat the small stuff, says DJ Taylor
Beige is back: The drab car colours of the 1970s are proving popular again

Beige to the future

Flares and flounce are back on catwalks but a revival in ’70s car paintjobs was a stack-heeled step too far – until now
Bill Granger recipes: Our chef's dishes highlight the delicate essence of fresh cheeses

Bill Granger cooks with fresh cheeses

More delicate on the palate, milder, fresh cheeses can also be kinder to the waistline
Aston Villa vs Liverpool: 'This FA Cup run has been wonderful,' says veteran Shay Given

Shay Given: 'This FA Cup run has been wonderful'

The Villa keeper has been overlooked for a long time and has unhappy memories of the national stadium – but he is savouring his chance to play at Wembley
Timeless drama of Championship race in league of its own - Michael Calvin

Michael Calvin's Last Word

Timeless drama of Championship race in league of its own