Why study the language of olfaction?
There are centuries-old ideas that humans have evolved to be visual or auditory creatures, and that our senses of smell, taste and touch just aren’t as important any more. We’re looking to see whether that’s reflected in different languages as well.

Are there languages which excel at describing smells?
Speakers of the – found throughout the Malay Peninsula – are particularly good at expressing olfactory experiences. For the Jahai group, for example, who live a hunter-gatherer lifestyle, we found that smell was as easy to talk about as colour – unlike in English.

How many smell words do the Jahai use?
They have about 12 that describe specific smell characteristics. These are words that can only be used for smells. For example, a term pronounced “pl’eng” is used for fresh blood, raw meat, mud, stagnant water, fresh fish, otters, some species of toad… These are different kinds of objects, but there seems to be a smell quality common to them.

What’s a good smell-specific word in English?
A term in English that really picks up on a specific kind of smell quality is “musty” – something like when you open a door that’s been closed for a long time, or maybe the smell of old books.

How good are English speakers at articulating what they smell?
We gave Jahai speakers and English speakers the same smell and asked them to describe it. Jahai speakers were quick and consistent. With English speakers, nearly everybody gave a different and lengthy description for the same smell. For the smell of cinnamon, for example, one participant went on and on, like “I don’t know how to say it” and “I can’t get the word” and “like that chewing gum smell” and finally “Big Red gum”. It was hard for most English speakers to identify even the common smell of cinnamon.

Why do English speakers struggle when the Jahai don’t?
Perhaps it’s because the Jahai live in a tropical rainforest, where smells are simply more salient. But there seems to be something culturally different, too: people in the West seem to do everything they can to get rid of smells, and in many contexts odour is a taboo topic. This might be linked to changes in our smell environment since the industrial revolution. If you read stories from the UK or France from before the revolution, there’s sewage in the streets and people are using perfume to cover up body odour. These days, we do everything we can to sanitise our environment.

What lessons do you draw from your cross-cultural studies of smell?
Our work with the Jahai is exciting because it shows us that we have the potential to experience our environment in so many different ways. It makes you rethink your way of being in the world.

This article appeared in print under the headline “Putting whiffs into words”

Barry Marshall experimented on himself to prove that H. pylori causes stomach ulcers and he won a Nobel prize. But what if the bug has a good side?

You discovered that the H. pylori bacterium causes stomach ulcers. But why do you now think it could help the immune system?
It could be that it modulates the immune system, stopping you from being too hyper-reactive. I think it may have helped early human migrations. If humans evolved in a tiny area of Africa, they only saw plants and animals within a 100-kilometre radius for a million years. When they began to migrate, there would have been different animals and plants – and potentially a lot of allergy issues. Maybe if they had H. pylori, it wasn’t so dangerous for them to meet all these different allergens.

Now, though, the bacterium is declining?
We know that every 10 to 20 years, in any country where the standard of living is rising – where the water is clean and the families smaller – it decreases by 10 per cent or so.

Could we bring it back, to boost immunity?
At my biotech company Ondek, housed at the University of Western Australia in Perth, we are developing new strains and different formulations of H. pylori, looking at how it changes the immune system. Mostly our work is in mice, so it’s not definitive. But we are going to move towards a clinical trial using an H. pylori product on people with allergies.

Could reintroducing H. pylori be dangerous?
The idea is to isolate a very safe strain. There are some really bad ones, and some weaker ones that aren’t so risky. We haven’t yet found one that is 100 per cent safe, but we think it is out there.

If the bacterium has been around for so long, why the surge in ulcers in the last century?
H. pylori damages the mucus layer that protects the stomach lining from acid. If you are infected with H. pylori and have a strong immune response as well as high acid secretion – both of which became more common as the standard of living and nutrition improved in the 20th century – that strong inflammatory response and robust acid secretion made an ulcer more likely.

The 20th-century ulcer epidemic was a sign of good health in American people – good diet, strong acidity and healthy immune response actually make ulcers more likely. That’s why businessmen eating giant T-bone steaks were prone to ulcers.

You famously experimented on yourself with H. pylori. Was that a risk for your career?
At that point my colleagues were treating ulcer patients as psychosomatic cases – using antidepressants, tranquilisers, psychotherapy, all that kind of thing. My career was already very shaky because I was ignoring the mental state of the patient and giving them antibiotics. Then my boss’s patients started secretly coming to my clinic for treatment. The politics have always been difficult in medicine. There is some truth in the way medical practice is portrayed in TV dramas.

Would you recommend self-experimentation in medicine today?
I haven’t asked people to let me do it again. But I think maybe because there was a useful outcome from my experiment, it’s probably easier to get permission nowadays.

This article appeared in print under the headline “Ulcer bug can be a boon”