Who knows what the nose knows? Well, it turns out scientists do. Researchers believe our sense of smell is much stronger than previously thought. A study published on Monday in the journal Nature Human Behaviour suggests that the human sense of smell can detect fine chemical changes within the duration of a single sniff.
The research suggests that our sense of smell might operate faster than previously thought and even faster than a blink. Researchers at the Chinese Academy of Sciences found that people can detect scents within 100 milliseconds of encountering them, a much faster response time than was believed.
The study, led by Dr Zhou Wen from the Institute of Psychology at the Academy, challenges prior assumptions that smell is a slower sense than sight or sound. Researchers suggest that this speed may have evolved to help humans quickly identify environmental dangers, such as spoiled food or smoke.
Dr. Zhou’s team developed a device that releases smells based on a sniff, with precise timing down to 18 milliseconds, which is about the speed of a single frame on a screen. Using this, they created sequences of two different smells, presented with short time gaps between them. They ran five experiments with 229 participants to see how well people could tell the difference between the two smells.
The participants were exposed to two different smells – one like apples and the other floral – through tubes of varying lengths. This meant one scent hit their nose about 120-180 milliseconds before the other. After sniffing twice, they had to say if the order of the smells was the same or reversed.
The results? They got it right 63% of the time, with 597 out of 952 correct guesses. A similar test with 70 more people using lemon and onion scents showed similar accuracy.
Interestingly, some participants who performed well could still tell the difference when the scents reached their noses 40-80 milliseconds apart. That’s about ten times faster than what was previously believed.
While the study has revealed interesting results about our sense of smell, it’s nothing compared to the super-powered noses in the animal kingdom. Some animals have a sense of smell far more powerful than ours. African elephants, for example, have about 2,000 olfactory receptor genes—five times more than humans—allowing them to detect water from nearly 19 kilometres away. Bloodhounds, often used for tracking people, have 230 million scent receptors and can follow a trail for days. Some sharks can pick up even the faintest traces of blood in the water, thanks to specialised organs in their heads. The kiwi bird from New Zealand uses its highly sensitive beak to smell food underground, making it one of the best smellers in the bird world. Lastly, rats, with over 1,200 olfactory receptor genes, are trained to sniff out explosives and even diseases like tuberculosis.
So, next time you take a whiff of an exciting perfume, remember that your sense of smell is exhibiting its superpower. The nose knows!
