The science of smell

The science behind our sense of smell is being used to improve humans – influencing everything from our dating lives, to our health

When it comes to dating, first impressions are everything. At the Royal Mirage Hotel in Dubai at the height of summer last year, men and women competed frantically to convince their would-be suitors of their eligibility. Except, instead of looks and personality, they were attempting to attract passers-by with smell. This was ‘the International Flavors & Fragrances’ (IFF) first ‘speed smelling’ event in the Middle East. The company, which sources and produces many of the world’s top smells, asked entrants to create unique scents, and gave them just seven minutes to impress attendees.

The Middle East has a long and enduring relationship with the art of perfume-making. The first recorded chemist, a woman named Tapputi, was a perfume-maker from Mesopotamia who distilled flowers, oil and calamus with other aromatics, in the second millennium BCE. Today, the world’s most exotic scents – oud, sandalwood and myrrh – are traded in the souks of Oman.

But our relationship with smell goes beyond the application of fragrances. For thousands of years, we have used scents to mark special occasions, commiserate the dead, commune with spirits, make us laugh and cry, and more recently, discover cancers inside us. Our sense of smell is more closely linked to memory and our past than any other and can provoke strong emotional reactions that bring us closer together, but also push us apart. Welcome to the science of smell.

olfactory nerve
The olfactory nerve is close to the amygdala, the ‘emotion centre’ of the brain

Research has shown that when areas of the brain connected to memory are damaged, the ability to identify smells is impaired. To identify a scent, you must recall when you have smelled it before and then connect it to visual information that occurred at the same time. Researchers at Northumbria University, Newcastle-upon-Tyne, discovered that studying information in the presence of an odour increases the vividness and intensity of remembered information when you smell that odour again.

But not all smells create a sense of nostalgia, and our ability to detect odours can be misleading. A few years ago, a man came to the Dubai clinic of Sumi Thomas, a dermatologist, saying he was in danger of losing his job due to his body odour. His colleagues complained to the company’s HR department, which asked him to correct the situation as it was affecting people’s work. But the patient couldn’t see, or rather, smell the problem.

Scientists are developing electronic systems (e-noses) that mimic the way dogs detect the smell of cancer

But while we’re beginning to unpack our own sense of smell, there are other species that are helping to save lives. In 2010, Japanese researchers showed that dogs can detect colorectal cancer from a breath sample, while in 2012 the European Respiratory Journal published research that found dogs could identify lung cancer in the same way. Dogs, whose sense of smell can be 10 million times more sensitive than our own, are being used in the UK to help doctors detect cancers without the need for expensive screening.

Medical Detection Dogs, a charity run by animal behavioural psychologist Dr Claire Guest, has a detection rate of 93 per cent. “A lot of cancers are difficult to detect in early stages,” Guest told the Daily Mail. But malignant cells produce changes in volatile organic compounds, and it’s these compounds that dogs are believed to detect in urine samples.
Scientists are now developing electronic systems (e-noses) that mimic the way dogs detect the smell of cancer. The NaNose, developed by a team of an international group of scientists, uses a breathalyser to detect early-stage lung cancer, a disease responsible for almost a third of all cancer-related deaths. With an accuracy on a par with Claire Guest’s dogs, researchers hope to be able to refine the device within a few years, replacing Fido’s role as doctor’s assistant.

While perfume-making may not be at the top of the military’s to-do list, the US navy is looking to use scent-sniffing robots to move 1,000-pound bombs on ships. The idea is that a human would control the lead robot and it would dispense the equivalent of a robot pheromone that a swarm of other robots would follow like army ants. It’s nothing to be sniffed at.